2023-11-23 13:58:39

by Stefan Förster

Subject: bcache: kernel NULL pointer dereference since 6.1.39

Hello world,

starting with kernel 6.1.39, we see the following error message with
heavy I/O loads. We needed to revert

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=68118c339c6e1e16ae017bef160dbe28a27ae9c8

to make sure the systems don't suddenly get stuck.

1. Kernel 6.6.2-arch1-1 on Dell Latitude:

[16816.214942] BUG: kernel NULL pointer dereference, address: 0000000000000080
[16816.214948] #PF: supervisor read access in kernel mode
[16816.214951] #PF: error_code(0x0000) - not-present page
[16816.214953] PGD 0 P4D 0
[16816.214956] Oops: 0000 [#1] PREEMPT SMP NOPTI
[16816.214960] CPU: 7 PID: 83416 Comm: bcache_gc Tainted: P OE 6.6.2-arch1-1 #1 11215f9ba7ddfb51644674a5b2ced71612c62fe9
[16816.214964] Hardware name: Dell Inc. Latitude 5431/06F77M, BIOS 1.17.0 09/21/2023
[16816.214965] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
[16816.214999] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f 44 00 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00 75
[16816.215001] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
[16816.215004] RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffff888515ce0670
[16816.215006] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI: 0000000000000000
[16816.215007] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09: 00000000013ffde8
[16816.215009] R10: 0000000000000000 R11: ffffc9000061b000 R12: ffffc90021777e40
[16816.215010] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15: ffff88819476c000
[16816.215011] FS: 0000000000000000(0000) GS:ffff88886fdc0000(0000) knlGS:0000000000000000
[16816.215013] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[16816.215015] CR2: 0000000000000080 CR3: 0000000294a20000 CR4: 0000000000f50ee0
[16816.215017] PKRU: 55555554
[16816.215018] Call Trace:
[16816.215021] <TASK>
[16816.215024] ? __die+0x23/0x70
[16816.215030] ? page_fault_oops+0x171/0x4e0
[16816.215035] ? __pfx_bch_ptr_bad+0x10/0x10 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215059] ? exc_page_fault+0x7f/0x180
[16816.215065] ? asm_exc_page_fault+0x26/0x30
[16816.215070] ? btree_node_free+0xf/0x160 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215095] ? btree_node_free+0xa3/0x160 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215118] btree_gc_coalesce+0x2a7/0x890 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215144] ? bch_extent_bad+0x81/0x190 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215172] btree_gc_recurse+0x130/0x390 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215197] ? btree_gc_mark_node+0x72/0x240 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215221] bch_btree_gc+0x4b6/0x620 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215246] ? __pfx_autoremove_wake_function+0x10/0x10
[16816.215250] ? __pfx_bch_gc_thread+0x10/0x10 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215272] bch_gc_thread+0x139/0x190 [bcache 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
[16816.215295] ? __pfx_autoremove_wake_function+0x10/0x10
[16816.215298] kthread+0xe5/0x120
[16816.215302] ? __pfx_kthread+0x10/0x10
[16816.215306] ret_from_fork+0x31/0x50
[16816.215309] ? __pfx_kthread+0x10/0x10
[16816.215312] ret_from_fork_asm+0x1b/0x30
[16816.215318] </TASK>
[16816.215319] Modules linked in: bcache tun ccm rfcomm snd_seq_dummy snd_hrtimer snd_seq nvidia(POE) typec_displayport cmac algif_hash algif_skcipher af_alg bnep hid_sensor_custom hid_sensor_hub intel_ishtp_hid snd_hda_codec_hdmi snd_sof_pci_intel_tgl snd_sof_intel_hda_common soundwire_intel snd_sof_intel_hda_mlink soundwire_cadence snd_sof_intel_hda snd_sof_pci snd_sof_xtensa_dsp snd_sof snd_sof_utils intel_uncore_frequency intel_uncore_frequency_common snd_ctl_led snd_soc_hdac_hda r8153_ecm snd_hda_ext_core iwlmvm cdc_ether snd_soc_acpi_intel_match usbnet snd_soc_acpi soundwire_generic_allocation soundwire_bus snd_soc_core x86_pkg_temp_thermal snd_compress snd_hda_codec_realtek intel_powerclamp ac97_bus snd_hda_codec_generic dell_rbtn coretemp btusb snd_pcm_dmaengine snd_usb_audio mac80211 btrtl snd_hda_intel kvm_intel btintel snd_intel_dspcfg snd_intel_sdw_acpi snd_usbmidi_lib btbcm dell_laptop snd_ump btmtk libarc4 snd_hda_codec uvcvideo kvm snd_rawmidi bluetooth snd_hda_core videobuf2_vmalloc hid_multitouch iwlwifi
[16816.215367] dell_wmi snd_hwdep iTCO_wdt snd_seq_device uvc nls_iso8859_1 videobuf2_memops dell_smbios intel_pmc_bxt mei_hdcp mei_pxp spi_nor snd_pcm processor_thermal_device_pci r8152 videobuf2_v4l2 dell_wmi_sysman irqbypass intel_rapl_msr dcdbas vfat iTCO_vendor_support fat rapl intel_cstate intel_uncore psmouse pcspkr dell_wmi_ddv firmware_attributes_class ledtrig_audio videobuf2_common ucsi_acpi dell_wmi_descriptor processor_thermal_device mousedev ecdh_generic snd_timer mii joydev mtd wmi_bmof e1000e cfg80211 processor_thermal_rfim mei_me intel_lpss_pci i2c_i801 snd processor_thermal_mbox typec_ucsi intel_ish_ipc intel_lpss mei soundcore i2c_smbus processor_thermal_rapl rfkill thunderbolt typec idma64 intel_ishtp roles intel_rapl_common igen6_edac i2c_hid_acpi int3403_thermal i2c_hid int340x_thermal_zone intel_hid int3400_thermal acpi_thermal_rel sparse_keymap acpi_tad acpi_pad mac_hid vboxnetflt(OE) vboxnetadp(OE) vboxdrv(OE) v4l2loopback(OE) videodev mc i2c_dev crypto_user fuse loop ip_tables x_tables ext4
[16816.215420] crc32c_generic crc16 mbcache jbd2 dm_crypt cbc encrypted_keys trusted asn1_encoder tee usbhid i915 dm_mod crct10dif_pclmul crc32_pclmul crc32c_intel polyval_clmulni i2c_algo_bit polyval_generic serio_raw rtsx_pci_sdmmc drm_buddy gf128mul atkbd ghash_clmulni_intel ttm mmc_core sha512_ssse3 libps2 vivaldi_fmap intel_gtt aesni_intel nvme crypto_simd drm_display_helper video nvme_core cryptd spi_intel_pci rtsx_pci spi_intel i8042 xhci_pci cec nvme_common xhci_pci_renesas serio wmi
[16816.215451] CR2: 0000000000000080
[16816.215453] ---[ end trace 0000000000000000 ]---
[16816.215455] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
[16816.215478] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f 44 00 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00 75
[16816.215480] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
[16816.215481] RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffff888515ce0670
[16816.215483] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI: 0000000000000000
[16816.215484] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09: 00000000013ffde8
[16816.215486] R10: 0000000000000000 R11: ffffc9000061b000 R12: ffffc90021777e40
[16816.215487] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15: ffff88819476c000
[16816.215488] FS: 0000000000000000(0000) GS:ffff88886fdc0000(0000) knlGS:0000000000000000
[16816.215490] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[16816.215492] CR2: 0000000000000080 CR3: 0000000294a20000 CR4: 0000000000f50ee0
[16816.215493] PKRU: 55555554
[16816.215494] note: bcache_gc[83416] exited with irqs disabled

2. Kernel 6.1.55 (Debian 6.1.0-13) on HPE Gen11:

[60654.670443] BUG: kernel NULL pointer dereference, address: 0000000000000080
[60654.677474] #PF: supervisor read access in kernel mode
[60654.682651] #PF: error_code(0x0000) - not-present page
[60654.687825] PGD 0
[60654.689852] Oops: 0000 [#1] PREEMPT SMP NOPTI
[60654.694240] CPU: 16 PID: 146330 Comm: bcache_gc Tainted: G W 6.1.0-13-amd64 #1 Debian 6.1.55-1
[60654.704399] Hardware name: HPE ProLiant DL380 Gen11/ProLiant DL380 Gen11, BIOS 1.48 10/19/2023
[60654.713071] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
[60654.718437] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f 44 00 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48 8d
[60654.737342] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
[60654.742604] RAX: 0000000080000000 RBX: 0000000000000000 RCX: 0000000000000000
[60654.749790] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI: 0000000000000000
[60654.756975] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09: ff2971b8de800000
[60654.764536] R10: 0000000000000000 R11: ff77daed34a4d000 R12: ff77daed34cc3e60
[60654.771987] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15: ff2971d851096400
[60654.779410] FS: 0000000000000000(0000) GS:ff2971f7bf400000(0000) knlGS:0000000000000000
[60654.787784] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[60654.793794] CR2: 0000000000000080 CR3: 0000000150610002 CR4: 0000000000771ee0
[60654.801203] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[60654.808609] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
[60654.816009] PKRU: 55555554
[60654.818949] Call Trace:
[60654.821623] <TASK>
[60654.823950] ? __die_body.cold+0x1a/0x1f
[60654.828110] ? page_fault_oops+0xd2/0x2b0
[60654.832352] ? exc_page_fault+0x70/0x170
[60654.836505] ? asm_exc_page_fault+0x22/0x30
[60654.840922] ? btree_node_free+0xf/0x160 [bcache]
[60654.845863] ? up_write+0x32/0x60
[60654.849396] btree_gc_coalesce+0x2aa/0x890 [bcache]
[60654.854512] ? bch_extent_bad+0x70/0x170 [bcache]
[60654.859452] btree_gc_recurse+0x130/0x390 [bcache]
[60654.864475] ? btree_gc_mark_node+0x72/0x230 [bcache]
[60654.869758] bch_btree_gc+0x5da/0x600 [bcache]
[60654.874428] ? cpuusage_read+0x10/0x10
[60654.878390] ? bch_btree_gc+0x600/0x600 [bcache]
[60654.883232] bch_gc_thread+0x135/0x180 [bcache]
[60654.887986] ? cpuusage_read+0x10/0x10
[60654.891944] kthread+0xe6/0x110
[60654.895290] ? kthread_complete_and_exit+0x20/0x20
[60654.900296] ret_from_fork+0x1f/0x30
[60654.904079] </TASK>
[60654.906455] Modules linked in: bonding tls cfg80211 rfkill intel_rapl_msr intel_rapl_common intel_uncore_frequency intel_uncore_frequency_common i10nm_edac nfit binfmt_misc libnvdimm x86_pkg_temp_thermal intel_powerclamp ipt_REJECT nf_reject_ipv4 coretemp xt_comment nft_compat nf_tables nfnetlink nls_ascii nls_cp437 kvm_intel vfat ipmi_ssif fat kvm irqbypass ghash_clmulni_intel sha512_ssse3 sha512_generic aesni_intel crypto_simd cryptd mgag200 drm_shmem_helper pmt_telemetry pmt_crashlog rapl intel_cstate acpi_ipmi evdev intel_sdsi pmt_class idxd hpwdt mei_me isst_if_mbox_pci isst_if_mmio drm_kms_helper intel_uncore pcspkr isst_if_common mei watchdog hpilo i2c_algo_bit ipmi_si idxd_bus acpi_tad intel_vsec sg acpi_power_meter button ipmi_devintf ipmi_msghandler loop fuse efi_pstore drm configfs efivarfs ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 btrfs blake2b_generic xor raid6_pq zstd_compress libcrc32c crc32c_generic ses enclosure bcache sd_mod scsi_transport_sas dm_mod nvme
[60654.906508] nvme_core xhci_pci t10_pi megaraid_sas ehci_pci xhci_hcd ehci_hcd crc64_rocksoft crc64 tg3 crc_t10dif scsi_mod usbcore crct10dif_generic crc32_pclmul crc32c_intel crct10dif_pclmul libphy scsi_common usb_common crct10dif_common wmi
[60655.017712] CR2: 0000000000000080
[60655.021262] ---[ end trace 0000000000000000 ]---
[60655.173744] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
[60655.179337] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f 44 00 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48 8d
[60655.198649] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
[60655.204121] RAX: 0000000080000000 RBX: 0000000000000000 RCX: 0000000000000000
[60655.211515] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI: 0000000000000000
[60655.218908] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09: ff2971b8de800000
[60655.226302] R10: 0000000000000000 R11: ff77daed34a4d000 R12: ff77daed34cc3e60
[60655.233696] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15: ff2971d851096400
[60655.241086] FS: 0000000000000000(0000) GS:ff2971f7bf400000(0000) knlGS:0000000000000000
[60655.249438] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[60655.255432] CR2: 0000000000000080 CR3: 0000000150610002 CR4: 0000000000771ee0
[60655.262825] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[60655.270218] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
[60655.277607] PKRU: 55555554
[60655.280543] note: bcache_gc[146330] exited with irqs disabled

Reproducer for us:

dd if=/dev/zero of=loop0 bs=1M count=1024
dd if=/dev/zero of=loop1 bs=1M count=10240
losetup loop0 loop0
losetup loop1 loop1
make-bcache -C /dev/loop0 -B /dev/loop1 --writeback
mkfs.ext4 /dev/bcache0
mount /dev/bcache0 /mnt

Then run fio with:

[global]
bs=4k
ioengine=libaio
iodepth=4
size=8g
direct=1
runtime=60
directory=/mnt
filename=ssd.test.file

[seq-write]
rw=write
stonewall

[rand-write]
rw=randwrite
stonewall

[seq-read]
rw=read
stonewall

[rand-read]
rw=randread
stonewall


Cheers,
Stefan

2023-11-24 06:20:19

by Thorsten Leemhuis

Subject: Re: bcache: kernel NULL pointer dereference since 6.1.39

On 23.11.23 14:53, Stefan Förster wrote:
>
> starting with kernel 6.1.39, we see the following error message with
> heavy I/O loads. We needed to revert

Thx for the report. I assume that problem still occurs with the latest
6.1.y kernel?

> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=68118c339c6e1e16ae017bef160dbe28a27ae9c8

FWIW, that is mainline commit 028ddcac477b69 ("bcache: Remove
unnecessary NULL point check in node allocations") [v6.5-rc1].

Did a quick check and noticed a fix for that change was recently
mainlined as f72f4312d43883 ("bcache: replace a mistaken IS_ERR() by
IS_ERR_OR_NULL() in btree_gc_coalesce()") [v6.7-rc2-post]:
https://lore.kernel.org/all/[email protected]/

It is expected to soon be interegrated into a 6.1.y kernel.

But maybe it's something else. I CCed the involved people, they might know.

Ciao, Thorsten

> to make sure the systems don't suddenly get stuck.
>
> 1. Kernel 6.6.2-arch1-1 on Dell Latitude:
>
> [16816.214942] BUG: kernel NULL pointer dereference, address:
> 0000000000000080
> [16816.214948] #PF: supervisor read access in kernel mode
> [16816.214951] #PF: error_code(0x0000) - not-present page
> [16816.214953] PGD 0 P4D 0 [16816.214956] Oops: 0000 [#1] PREEMPT SMP NOPTI
> [16816.214960] CPU: 7 PID: 83416 Comm: bcache_gc Tainted: P          
> OE      6.6.2-arch1-1 #1 11215f9ba7ddfb51644674a5b2ced71612c62fe9
> [16816.214964] Hardware name: Dell Inc. Latitude 5431/06F77M, BIOS
> 1.17.0 09/21/2023
> [16816.214965] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> [16816.214999] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90
> 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f 44 00
> 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00 75
> [16816.215001] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
> [16816.215004] RAX: 0000000000000001 RBX: 0000000000000000 RCX:
> ffff888515ce0670
> [16816.215006] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI:
> 0000000000000000
> [16816.215007] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09:
> 00000000013ffde8
> [16816.215009] R10: 0000000000000000 R11: ffffc9000061b000 R12:
> ffffc90021777e40
> [16816.215010] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15:
> ffff88819476c000
> [16816.215011] FS:  0000000000000000(0000) GS:ffff88886fdc0000(0000)
> knlGS:0000000000000000
> [16816.215013] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [16816.215015] CR2: 0000000000000080 CR3: 0000000294a20000 CR4:
> 0000000000f50ee0
> [16816.215017] PKRU: 55555554
> [16816.215018] Call Trace:
> [16816.215021]  <TASK>
> [16816.215024]  ? __die+0x23/0x70
> [16816.215030]  ? page_fault_oops+0x171/0x4e0
> [16816.215035]  ? __pfx_bch_ptr_bad+0x10/0x10 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215059]  ? exc_page_fault+0x7f/0x180
> [16816.215065]  ? asm_exc_page_fault+0x26/0x30
> [16816.215070]  ? btree_node_free+0xf/0x160 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215095]  ? btree_node_free+0xa3/0x160 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215118]  btree_gc_coalesce+0x2a7/0x890 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215144]  ? bch_extent_bad+0x81/0x190 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215172]  btree_gc_recurse+0x130/0x390 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215197]  ? btree_gc_mark_node+0x72/0x240 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215221]  bch_btree_gc+0x4b6/0x620 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215246]  ? __pfx_autoremove_wake_function+0x10/0x10
> [16816.215250]  ? __pfx_bch_gc_thread+0x10/0x10 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215272]  bch_gc_thread+0x139/0x190 [bcache
> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> [16816.215295]  ? __pfx_autoremove_wake_function+0x10/0x10
> [16816.215298]  kthread+0xe5/0x120
> [16816.215302]  ? __pfx_kthread+0x10/0x10
> [16816.215306]  ret_from_fork+0x31/0x50
> [16816.215309]  ? __pfx_kthread+0x10/0x10
> [16816.215312]  ret_from_fork_asm+0x1b/0x30
> [16816.215318]  </TASK>
> [16816.215319] Modules linked in: bcache tun ccm rfcomm snd_seq_dummy
> snd_hrtimer snd_seq nvidia(POE) typec_displayport cmac algif_hash
> algif_skcipher af_alg bnep hid_sensor_custom hid_sensor_hub
> intel_ishtp_hid snd_hda_codec_hdmi snd_sof_pci_intel_tgl
> snd_sof_intel_hda_common soundwire_intel snd_sof_intel_hda_mlink
> soundwire_cadence snd_sof_intel_hda snd_sof_pci snd_sof_xtensa_dsp
> snd_sof snd_sof_utils intel_uncore_frequency
> intel_uncore_frequency_common snd_ctl_led snd_soc_hdac_hda r8153_ecm
> snd_hda_ext_core iwlmvm cdc_ether snd_soc_acpi_intel_match usbnet
> snd_soc_acpi soundwire_generic_allocation soundwire_bus snd_soc_core
> x86_pkg_temp_thermal snd_compress snd_hda_codec_realtek intel_powerclamp
> ac97_bus snd_hda_codec_generic dell_rbtn coretemp btusb
> snd_pcm_dmaengine snd_usb_audio mac80211 btrtl snd_hda_intel kvm_intel
> btintel snd_intel_dspcfg snd_intel_sdw_acpi snd_usbmidi_lib btbcm
> dell_laptop snd_ump btmtk libarc4 snd_hda_codec uvcvideo kvm snd_rawmidi
> bluetooth snd_hda_core videobuf2_vmalloc hid_multitouch iwlwifi
> [16816.215367]  dell_wmi snd_hwdep iTCO_wdt snd_seq_device uvc
> nls_iso8859_1 videobuf2_memops dell_smbios intel_pmc_bxt mei_hdcp
> mei_pxp spi_nor snd_pcm processor_thermal_device_pci r8152
> videobuf2_v4l2 dell_wmi_sysman irqbypass intel_rapl_msr dcdbas vfat
> iTCO_vendor_support fat rapl intel_cstate intel_uncore psmouse pcspkr
> dell_wmi_ddv firmware_attributes_class ledtrig_audio videobuf2_common
> ucsi_acpi dell_wmi_descriptor processor_thermal_device mousedev
> ecdh_generic snd_timer mii joydev mtd wmi_bmof e1000e cfg80211
> processor_thermal_rfim mei_me intel_lpss_pci i2c_i801 snd
> processor_thermal_mbox typec_ucsi intel_ish_ipc intel_lpss mei soundcore
> i2c_smbus processor_thermal_rapl rfkill thunderbolt typec idma64
> intel_ishtp roles intel_rapl_common igen6_edac i2c_hid_acpi
> int3403_thermal i2c_hid int340x_thermal_zone intel_hid int3400_thermal
> acpi_thermal_rel sparse_keymap acpi_tad acpi_pad mac_hid vboxnetflt(OE)
> vboxnetadp(OE) vboxdrv(OE) v4l2loopback(OE) videodev mc i2c_dev
> crypto_user fuse loop ip_tables x_tables ext4
> [16816.215420]  crc32c_generic crc16 mbcache jbd2 dm_crypt cbc
> encrypted_keys trusted asn1_encoder tee usbhid i915 dm_mod
> crct10dif_pclmul crc32_pclmul crc32c_intel polyval_clmulni i2c_algo_bit
> polyval_generic serio_raw rtsx_pci_sdmmc drm_buddy gf128mul atkbd
> ghash_clmulni_intel ttm mmc_core sha512_ssse3 libps2 vivaldi_fmap
> intel_gtt aesni_intel nvme crypto_simd drm_display_helper video
> nvme_core cryptd spi_intel_pci rtsx_pci spi_intel i8042 xhci_pci cec
> nvme_common xhci_pci_renesas serio wmi
> [16816.215451] CR2: 0000000000000080
> [16816.215453] ---[ end trace 0000000000000000 ]---
> [16816.215455] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> [16816.215478] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90
> 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f 44 00
> 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00 75
> [16816.215480] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
> [16816.215481] RAX: 0000000000000001 RBX: 0000000000000000 RCX:
> ffff888515ce0670
> [16816.215483] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI:
> 0000000000000000
> [16816.215484] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09:
> 00000000013ffde8
> [16816.215486] R10: 0000000000000000 R11: ffffc9000061b000 R12:
> ffffc90021777e40
> [16816.215487] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15:
> ffff88819476c000
> [16816.215488] FS:  0000000000000000(0000) GS:ffff88886fdc0000(0000)
> knlGS:0000000000000000
> [16816.215490] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [16816.215492] CR2: 0000000000000080 CR3: 0000000294a20000 CR4:
> 0000000000f50ee0
> [16816.215493] PKRU: 55555554
> [16816.215494] note: bcache_gc[83416] exited with irqs disabled
>
> 2. Kernel 6.1.55 (Debian 6.1.0-13) on HPE Gen11:
>
> [60654.670443] BUG: kernel NULL pointer dereference, address:
> 0000000000000080
> [60654.677474] #PF: supervisor read access in kernel mode
> [60654.682651] #PF: error_code(0x0000) - not-present page
> [60654.687825] PGD 0 [60654.689852] Oops: 0000 [#1] PREEMPT SMP NOPTI
> [60654.694240] CPU: 16 PID: 146330 Comm: bcache_gc Tainted: G       
> W          6.1.0-13-amd64 #1  Debian 6.1.55-1
> [60654.704399] Hardware name: HPE ProLiant DL380 Gen11/ProLiant DL380
> Gen11, BIOS 1.48 10/19/2023
> [60654.713071] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> [60654.718437] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc 66 66
> 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f 44 00
> 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48 8d
> [60654.737342] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
> [60654.742604] RAX: 0000000080000000 RBX: 0000000000000000 RCX:
> 0000000000000000
> [60654.749790] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI:
> 0000000000000000
> [60654.756975] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09:
> ff2971b8de800000
> [60654.764536] R10: 0000000000000000 R11: ff77daed34a4d000 R12:
> ff77daed34cc3e60
> [60654.771987] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15:
> ff2971d851096400
> [60654.779410] FS:  0000000000000000(0000) GS:ff2971f7bf400000(0000)
> knlGS:0000000000000000
> [60654.787784] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [60654.793794] CR2: 0000000000000080 CR3: 0000000150610002 CR4:
> 0000000000771ee0
> [60654.801203] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [60654.808609] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7:
> 0000000000000400
> [60654.816009] PKRU: 55555554
> [60654.818949] Call Trace:
> [60654.821623]  <TASK>
> [60654.823950]  ? __die_body.cold+0x1a/0x1f
> [60654.828110]  ? page_fault_oops+0xd2/0x2b0
> [60654.832352]  ? exc_page_fault+0x70/0x170
> [60654.836505]  ? asm_exc_page_fault+0x22/0x30
> [60654.840922]  ? btree_node_free+0xf/0x160 [bcache]
> [60654.845863]  ? up_write+0x32/0x60
> [60654.849396]  btree_gc_coalesce+0x2aa/0x890 [bcache]
> [60654.854512]  ? bch_extent_bad+0x70/0x170 [bcache]
> [60654.859452]  btree_gc_recurse+0x130/0x390 [bcache]
> [60654.864475]  ? btree_gc_mark_node+0x72/0x230 [bcache]
> [60654.869758]  bch_btree_gc+0x5da/0x600 [bcache]
> [60654.874428]  ? cpuusage_read+0x10/0x10
> [60654.878390]  ? bch_btree_gc+0x600/0x600 [bcache]
> [60654.883232]  bch_gc_thread+0x135/0x180 [bcache]
> [60654.887986]  ? cpuusage_read+0x10/0x10
> [60654.891944]  kthread+0xe6/0x110
> [60654.895290]  ? kthread_complete_and_exit+0x20/0x20
> [60654.900296]  ret_from_fork+0x1f/0x30
> [60654.904079]  </TASK>
> [60654.906455] Modules linked in: bonding tls cfg80211 rfkill
> intel_rapl_msr intel_rapl_common intel_uncore_frequency
> intel_uncore_frequency_common i10nm_edac nfit binfmt_misc libnvdimm
> x86_pkg_temp_thermal intel_powerclamp ipt_REJECT nf_reject_ipv4 coretemp
> xt_comment nft_compat nf_tables nfnetlink nls_ascii nls_cp437 kvm_intel
> vfat ipmi_ssif fat kvm irqbypass ghash_clmulni_intel sha512_ssse3
> sha512_generic aesni_intel crypto_simd cryptd mgag200 drm_shmem_helper
> pmt_telemetry pmt_crashlog rapl intel_cstate acpi_ipmi evdev intel_sdsi
> pmt_class idxd hpwdt mei_me isst_if_mbox_pci isst_if_mmio drm_kms_helper
> intel_uncore pcspkr isst_if_common mei watchdog hpilo i2c_algo_bit
> ipmi_si idxd_bus acpi_tad intel_vsec sg acpi_power_meter button
> ipmi_devintf ipmi_msghandler loop fuse efi_pstore drm configfs efivarfs
> ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 btrfs blake2b_generic
> xor raid6_pq zstd_compress libcrc32c crc32c_generic ses enclosure bcache
> sd_mod scsi_transport_sas dm_mod nvme
> [60654.906508]  nvme_core xhci_pci t10_pi megaraid_sas ehci_pci xhci_hcd
> ehci_hcd crc64_rocksoft crc64 tg3 crc_t10dif scsi_mod usbcore
> crct10dif_generic crc32_pclmul crc32c_intel crct10dif_pclmul libphy
> scsi_common usb_common crct10dif_common wmi
> [60655.017712] CR2: 0000000000000080
> [60655.021262] ---[ end trace 0000000000000000 ]---
> [60655.173744] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> [60655.179337] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc 66 66
> 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f 44 00
> 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48 8d
> [60655.198649] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
> [60655.204121] RAX: 0000000080000000 RBX: 0000000000000000 RCX:
> 0000000000000000
> [60655.211515] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI:
> 0000000000000000
> [60655.218908] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09:
> ff2971b8de800000
> [60655.226302] R10: 0000000000000000 R11: ff77daed34a4d000 R12:
> ff77daed34cc3e60
> [60655.233696] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15:
> ff2971d851096400
> [60655.241086] FS:  0000000000000000(0000) GS:ff2971f7bf400000(0000)
> knlGS:0000000000000000
> [60655.249438] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [60655.255432] CR2: 0000000000000080 CR3: 0000000150610002 CR4:
> 0000000000771ee0
> [60655.262825] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [60655.270218] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7:
> 0000000000000400
> [60655.277607] PKRU: 55555554
> [60655.280543] note: bcache_gc[146330] exited with irqs disabled
>
> Reproducer for us:
>
> dd if=/dev/zero of=loop0 bs=1M count=1024
> dd if=/dev/zero of=loop1 bs=1M count=10240
> losetup loop0 loop0
> losetup loop1 loop1
> make-bcache -C /dev/loop0 -B /dev/loop1 --writeback
> mkfs.ext4 /dev/bcache0
> mount /dev/bcache0 /mnt
>
> Then run fio with:
>
> [global]
> bs=4k
> ioengine=libaio
> iodepth=4
> size=8g
> direct=1
> runtime=60
> directory=/mnt
> filename=ssd.test.file
>
> [seq-write]
> rw=write
> stonewall
>
> [rand-write]
> rw=randwrite
> stonewall
>
> [seq-read]
> rw=read
> stonewall
>
> [rand-read]
> rw=randread
> stonewall
>
>
> Cheers,
> Stefan

2023-11-24 13:34:46

by Markus Weippert

Subject: Re: bcache: kernel NULL pointer dereference since 6.1.39

> On 23.11.23 14:53, Stefan Förster wrote:
> >
> > starting with kernel 6.1.39, we see the following error message
> > with
> > heavy I/O loads. We needed to revert
>
> Thx for the report. I assume that problem still occurs with the
> latest
> 6.1.y kernel?
>
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=68118c339c6e1e16ae017bef160dbe28a27ae9c8
>
> FWIW, that is mainline commit 028ddcac477b69 ("bcache: Remove
> unnecessary NULL point check in node allocations") [v6.5-rc1].
>
> Did a quick check and noticed a fix for that change was recently
> mainlined as f72f4312d43883 ("bcache: replace a mistaken IS_ERR() by
> IS_ERR_OR_NULL() in btree_gc_coalesce()") [v6.7-rc2-post]:
> https://lore.kernel.org/all/[email protected]/
>
> It is expected to soon be interegrated into a 6.1.y kernel.
>
> But maybe it's something else. I CCed the involved people, they might
> know.

We applied f72f4312d43883 to the current Debian kernel (based on
6.1.55) but it didn't help, same stack trace.
Looking at the description, __bch_btree_node_alloc() should never be
able to return NULL anyway after
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=7ecea5ce3dc17339c280c75b58ac93d8c8620d9f
But I didn't verify all callers, so this might still be correct, if
it's not always initialized with the return value of
__bch_btree_node_alloc().

Anyway, I think we fixed it by applying this:

diff -Naurp a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
--- a/drivers/md/bcache/btree.c 2023-09-23 11:11:13.000000000 +0200
+++ b/drivers/md/bcache/btree.c 2023-11-24 13:13:09.840013759 +0100
@@ -1489,7 +1489,7 @@ out_nocoalesce:
bch_keylist_free(&keylist);

for (i = 0; i < nodes; i++)
- if (!IS_ERR(new_nodes[i])) {
+ if (!IS_ERR_OR_NULL(new_nodes[i])) {
btree_node_free(new_nodes[i]);
rw_unlock(true, new_nodes[i]);
}

--

That seems to run stable now. I suppose the culprit is here:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/md/bcache/btree.c?h=v6.1.55#n1448

new_nodes[0] = NULL;

for (i = 0; i < nodes; i++) {
if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b-
>key)))
goto out_nocoalesce;


So if __bch_keylist_realloc() succeeds, then btree_node_free() will be
called with new_nodes[0] which is NULL.

This is still the same in mainline:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/md/bcache/btree.c?id=31f5b956a197d4ec25c8a07cb3a2ab69d0c0b82f#n1481



>
> Ciao, Thorsten
>
> > to make sure the systems don't suddenly get stuck.
> >
> > 1. Kernel 6.6.2-arch1-1 on Dell Latitude:
> >
> > [16816.214942] BUG: kernel NULL pointer dereference, address:
> > 0000000000000080
> > [16816.214948] #PF: supervisor read access in kernel mode
> > [16816.214951] #PF: error_code(0x0000) - not-present page
> > [16816.214953] PGD 0 P4D 0 [16816.214956] Oops: 0000 [#1] PREEMPT
> > SMP NOPTI
> > [16816.214960] CPU: 7 PID: 83416 Comm: bcache_gc Tainted:
> > P          
> > OE      6.6.2-arch1-1 #1 11215f9ba7ddfb51644674a5b2ced71612c62fe9
> > [16816.214964] Hardware name: Dell Inc. Latitude 5431/06F77M, BIOS
> > 1.17.0 09/21/2023
> > [16816.214965] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> > [16816.214999] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90
> > 90 90
> > 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f
> > 44 00
> > 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00
> > 75
> > [16816.215001] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
> > [16816.215004] RAX: 0000000000000001 RBX: 0000000000000000 RCX:
> > ffff888515ce0670
> > [16816.215006] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI:
> > 0000000000000000
> > [16816.215007] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09:
> > 00000000013ffde8
> > [16816.215009] R10: 0000000000000000 R11: ffffc9000061b000 R12:
> > ffffc90021777e40
> > [16816.215010] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15:
> > ffff88819476c000
> > [16816.215011] FS:  0000000000000000(0000)
> > GS:ffff88886fdc0000(0000)
> > knlGS:0000000000000000
> > [16816.215013] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [16816.215015] CR2: 0000000000000080 CR3: 0000000294a20000 CR4:
> > 0000000000f50ee0
> > [16816.215017] PKRU: 55555554
> > [16816.215018] Call Trace:
> > [16816.215021]  <TASK>
> > [16816.215024]  ? __die+0x23/0x70
> > [16816.215030]  ? page_fault_oops+0x171/0x4e0
> > [16816.215035]  ? __pfx_bch_ptr_bad+0x10/0x10 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215059]  ? exc_page_fault+0x7f/0x180
> > [16816.215065]  ? asm_exc_page_fault+0x26/0x30
> > [16816.215070]  ? btree_node_free+0xf/0x160 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215095]  ? btree_node_free+0xa3/0x160 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215118]  btree_gc_coalesce+0x2a7/0x890 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215144]  ? bch_extent_bad+0x81/0x190 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215172]  btree_gc_recurse+0x130/0x390 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215197]  ? btree_gc_mark_node+0x72/0x240 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215221]  bch_btree_gc+0x4b6/0x620 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215246]  ? __pfx_autoremove_wake_function+0x10/0x10
> > [16816.215250]  ? __pfx_bch_gc_thread+0x10/0x10 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215272]  bch_gc_thread+0x139/0x190 [bcache
> > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > [16816.215295]  ? __pfx_autoremove_wake_function+0x10/0x10
> > [16816.215298]  kthread+0xe5/0x120
> > [16816.215302]  ? __pfx_kthread+0x10/0x10
> > [16816.215306]  ret_from_fork+0x31/0x50
> > [16816.215309]  ? __pfx_kthread+0x10/0x10
> > [16816.215312]  ret_from_fork_asm+0x1b/0x30
> > [16816.215318]  </TASK>
> > [16816.215319] Modules linked in: bcache tun ccm rfcomm
> > snd_seq_dummy
> > snd_hrtimer snd_seq nvidia(POE) typec_displayport cmac algif_hash
> > algif_skcipher af_alg bnep hid_sensor_custom hid_sensor_hub
> > intel_ishtp_hid snd_hda_codec_hdmi snd_sof_pci_intel_tgl
> > snd_sof_intel_hda_common soundwire_intel snd_sof_intel_hda_mlink
> > soundwire_cadence snd_sof_intel_hda snd_sof_pci snd_sof_xtensa_dsp
> > snd_sof snd_sof_utils intel_uncore_frequency
> > intel_uncore_frequency_common snd_ctl_led snd_soc_hdac_hda
> > r8153_ecm
> > snd_hda_ext_core iwlmvm cdc_ether snd_soc_acpi_intel_match usbnet
> > snd_soc_acpi soundwire_generic_allocation soundwire_bus
> > snd_soc_core
> > x86_pkg_temp_thermal snd_compress snd_hda_codec_realtek
> > intel_powerclamp
> > ac97_bus snd_hda_codec_generic dell_rbtn coretemp btusb
> > snd_pcm_dmaengine snd_usb_audio mac80211 btrtl snd_hda_intel
> > kvm_intel
> > btintel snd_intel_dspcfg snd_intel_sdw_acpi snd_usbmidi_lib btbcm
> > dell_laptop snd_ump btmtk libarc4 snd_hda_codec uvcvideo kvm
> > snd_rawmidi
> > bluetooth snd_hda_core videobuf2_vmalloc hid_multitouch iwlwifi
> > [16816.215367]  dell_wmi snd_hwdep iTCO_wdt snd_seq_device uvc
> > nls_iso8859_1 videobuf2_memops dell_smbios intel_pmc_bxt mei_hdcp
> > mei_pxp spi_nor snd_pcm processor_thermal_device_pci r8152
> > videobuf2_v4l2 dell_wmi_sysman irqbypass intel_rapl_msr dcdbas vfat
> > iTCO_vendor_support fat rapl intel_cstate intel_uncore psmouse
> > pcspkr
> > dell_wmi_ddv firmware_attributes_class ledtrig_audio
> > videobuf2_common
> > ucsi_acpi dell_wmi_descriptor processor_thermal_device mousedev
> > ecdh_generic snd_timer mii joydev mtd wmi_bmof e1000e cfg80211
> > processor_thermal_rfim mei_me intel_lpss_pci i2c_i801 snd
> > processor_thermal_mbox typec_ucsi intel_ish_ipc intel_lpss mei
> > soundcore
> > i2c_smbus processor_thermal_rapl rfkill thunderbolt typec idma64
> > intel_ishtp roles intel_rapl_common igen6_edac i2c_hid_acpi
> > int3403_thermal i2c_hid int340x_thermal_zone intel_hid
> > int3400_thermal
> > acpi_thermal_rel sparse_keymap acpi_tad acpi_pad mac_hid
> > vboxnetflt(OE)
> > vboxnetadp(OE) vboxdrv(OE) v4l2loopback(OE) videodev mc i2c_dev
> > crypto_user fuse loop ip_tables x_tables ext4
> > [16816.215420]  crc32c_generic crc16 mbcache jbd2 dm_crypt cbc
> > encrypted_keys trusted asn1_encoder tee usbhid i915 dm_mod
> > crct10dif_pclmul crc32_pclmul crc32c_intel polyval_clmulni
> > i2c_algo_bit
> > polyval_generic serio_raw rtsx_pci_sdmmc drm_buddy gf128mul atkbd
> > ghash_clmulni_intel ttm mmc_core sha512_ssse3 libps2 vivaldi_fmap
> > intel_gtt aesni_intel nvme crypto_simd drm_display_helper video
> > nvme_core cryptd spi_intel_pci rtsx_pci spi_intel i8042 xhci_pci
> > cec
> > nvme_common xhci_pci_renesas serio wmi
> > [16816.215451] CR2: 0000000000000080
> > [16816.215453] ---[ end trace 0000000000000000 ]---
> > [16816.215455] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> > [16816.215478] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90
> > 90 90
> > 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f
> > 44 00
> > 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00
> > 75
> > [16816.215480] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
> > [16816.215481] RAX: 0000000000000001 RBX: 0000000000000000 RCX:
> > ffff888515ce0670
> > [16816.215483] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI:
> > 0000000000000000
> > [16816.215484] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09:
> > 00000000013ffde8
> > [16816.215486] R10: 0000000000000000 R11: ffffc9000061b000 R12:
> > ffffc90021777e40
> > [16816.215487] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15:
> > ffff88819476c000
> > [16816.215488] FS:  0000000000000000(0000)
> > GS:ffff88886fdc0000(0000)
> > knlGS:0000000000000000
> > [16816.215490] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [16816.215492] CR2: 0000000000000080 CR3: 0000000294a20000 CR4:
> > 0000000000f50ee0
> > [16816.215493] PKRU: 55555554
> > [16816.215494] note: bcache_gc[83416] exited with irqs disabled
> >
> > 2. Kernel 6.1.55 (Debian 6.1.0-13) on HPE Gen11:
> >
> > [60654.670443] BUG: kernel NULL pointer dereference, address:
> > 0000000000000080
> > [60654.677474] #PF: supervisor read access in kernel mode
> > [60654.682651] #PF: error_code(0x0000) - not-present page
> > [60654.687825] PGD 0 [60654.689852] Oops: 0000 [#1] PREEMPT SMP
> > NOPTI
> > [60654.694240] CPU: 16 PID: 146330 Comm: bcache_gc Tainted:
> > G       
> > W          6.1.0-13-amd64 #1  Debian 6.1.55-1
> > [60654.704399] Hardware name: HPE ProLiant DL380 Gen11/ProLiant
> > DL380
> > Gen11, BIOS 1.48 10/19/2023
> > [60654.713071] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> > [60654.718437] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc
> > 66 66
> > 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f
> > 44 00
> > 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48
> > 8d
> > [60654.737342] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
> > [60654.742604] RAX: 0000000080000000 RBX: 0000000000000000 RCX:
> > 0000000000000000
> > [60654.749790] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI:
> > 0000000000000000
> > [60654.756975] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09:
> > ff2971b8de800000
> > [60654.764536] R10: 0000000000000000 R11: ff77daed34a4d000 R12:
> > ff77daed34cc3e60
> > [60654.771987] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15:
> > ff2971d851096400
> > [60654.779410] FS:  0000000000000000(0000)
> > GS:ff2971f7bf400000(0000)
> > knlGS:0000000000000000
> > [60654.787784] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [60654.793794] CR2: 0000000000000080 CR3: 0000000150610002 CR4:
> > 0000000000771ee0
> > [60654.801203] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> > 0000000000000000
> > [60654.808609] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7:
> > 0000000000000400
> > [60654.816009] PKRU: 55555554
> > [60654.818949] Call Trace:
> > [60654.821623]  <TASK>
> > [60654.823950]  ? __die_body.cold+0x1a/0x1f
> > [60654.828110]  ? page_fault_oops+0xd2/0x2b0
> > [60654.832352]  ? exc_page_fault+0x70/0x170
> > [60654.836505]  ? asm_exc_page_fault+0x22/0x30
> > [60654.840922]  ? btree_node_free+0xf/0x160 [bcache]
> > [60654.845863]  ? up_write+0x32/0x60
> > [60654.849396]  btree_gc_coalesce+0x2aa/0x890 [bcache]
> > [60654.854512]  ? bch_extent_bad+0x70/0x170 [bcache]
> > [60654.859452]  btree_gc_recurse+0x130/0x390 [bcache]
> > [60654.864475]  ? btree_gc_mark_node+0x72/0x230 [bcache]
> > [60654.869758]  bch_btree_gc+0x5da/0x600 [bcache]
> > [60654.874428]  ? cpuusage_read+0x10/0x10
> > [60654.878390]  ? bch_btree_gc+0x600/0x600 [bcache]
> > [60654.883232]  bch_gc_thread+0x135/0x180 [bcache]
> > [60654.887986]  ? cpuusage_read+0x10/0x10
> > [60654.891944]  kthread+0xe6/0x110
> > [60654.895290]  ? kthread_complete_and_exit+0x20/0x20
> > [60654.900296]  ret_from_fork+0x1f/0x30
> > [60654.904079]  </TASK>
> > [60654.906455] Modules linked in: bonding tls cfg80211 rfkill
> > intel_rapl_msr intel_rapl_common intel_uncore_frequency
> > intel_uncore_frequency_common i10nm_edac nfit binfmt_misc libnvdimm
> > x86_pkg_temp_thermal intel_powerclamp ipt_REJECT nf_reject_ipv4
> > coretemp
> > xt_comment nft_compat nf_tables nfnetlink nls_ascii nls_cp437
> > kvm_intel
> > vfat ipmi_ssif fat kvm irqbypass ghash_clmulni_intel sha512_ssse3
> > sha512_generic aesni_intel crypto_simd cryptd mgag200
> > drm_shmem_helper
> > pmt_telemetry pmt_crashlog rapl intel_cstate acpi_ipmi evdev
> > intel_sdsi
> > pmt_class idxd hpwdt mei_me isst_if_mbox_pci isst_if_mmio
> > drm_kms_helper
> > intel_uncore pcspkr isst_if_common mei watchdog hpilo i2c_algo_bit
> > ipmi_si idxd_bus acpi_tad intel_vsec sg acpi_power_meter button
> > ipmi_devintf ipmi_msghandler loop fuse efi_pstore drm configfs
> > efivarfs
> > ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 btrfs
> > blake2b_generic
> > xor raid6_pq zstd_compress libcrc32c crc32c_generic ses enclosure
> > bcache
> > sd_mod scsi_transport_sas dm_mod nvme
> > [60654.906508]  nvme_core xhci_pci t10_pi megaraid_sas ehci_pci
> > xhci_hcd
> > ehci_hcd crc64_rocksoft crc64 tg3 crc_t10dif scsi_mod usbcore
> > crct10dif_generic crc32_pclmul crc32c_intel crct10dif_pclmul libphy
> > scsi_common usb_common crct10dif_common wmi
> > [60655.017712] CR2: 0000000000000080
> > [60655.021262] ---[ end trace 0000000000000000 ]---
> > [60655.173744] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> > [60655.179337] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc
> > 66 66
> > 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f
> > 44 00
> > 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48
> > 8d
> > [60655.198649] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
> > [60655.204121] RAX: 0000000080000000 RBX: 0000000000000000 RCX:
> > 0000000000000000
> > [60655.211515] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI:
> > 0000000000000000
> > [60655.218908] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09:
> > ff2971b8de800000
> > [60655.226302] R10: 0000000000000000 R11: ff77daed34a4d000 R12:
> > ff77daed34cc3e60
> > [60655.233696] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15:
> > ff2971d851096400
> > [60655.241086] FS:  0000000000000000(0000)
> > GS:ff2971f7bf400000(0000)
> > knlGS:0000000000000000
> > [60655.249438] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [60655.255432] CR2: 0000000000000080 CR3: 0000000150610002 CR4:
> > 0000000000771ee0
> > [60655.262825] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> > 0000000000000000
> > [60655.270218] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7:
> > 0000000000000400
> > [60655.277607] PKRU: 55555554
> > [60655.280543] note: bcache_gc[146330] exited with irqs disabled
> >
> > Reproducer for us:
> >
> > dd if=/dev/zero of=loop0 bs=1M count=1024
> > dd if=/dev/zero of=loop1 bs=1M count=10240
> > losetup loop0 loop0
> > losetup loop1 loop1
> > make-bcache -C /dev/loop0 -B /dev/loop1 --writeback
> > mkfs.ext4 /dev/bcache0
> > mount /dev/bcache0 /mnt
> >
> > Then run fio with:
> >
> > [global]
> > bs=4k
> > ioengine=libaio
> > iodepth=4
> > size=8g
> > direct=1
> > runtime=60
> > directory=/mnt
> > filename=ssd.test.file
> >
> > [seq-write]
> > rw=write
> > stonewall
> >
> > [rand-write]
> > rw=randwrite
> > stonewall
> >
> > [seq-read]
> > rw=read
> > stonewall
> >
> > [rand-read]
> > rw=randread
> > stonewall
> >
> >
> > Cheers,
> > Stefan

2023-11-24 13:52:48

by Coly Li

Subject: Re: bcache: kernel NULL pointer dereference since 6.1.39

> 2023年11月24日 21:29，Markus Weippert <[email protected]> 写道：
>
>> On 23.11.23 14:53, Stefan Förster wrote:
>>>
>>> starting with kernel 6.1.39, we see the following error message
>>> with
>>> heavy I/O loads. We needed to revert
>>
>> Thx for the report. I assume that problem still occurs with the
>> latest
>> 6.1.y kernel?
>>
>>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=68118c339c6e1e16ae017bef160dbe28a27ae9c8
>>
>> FWIW, that is mainline commit 028ddcac477b69 ("bcache: Remove
>> unnecessary NULL point check in node allocations") [v6.5-rc1].
>>
>> Did a quick check and noticed a fix for that change was recently
>> mainlined as f72f4312d43883 ("bcache: replace a mistaken IS_ERR() by
>> IS_ERR_OR_NULL() in btree_gc_coalesce()") [v6.7-rc2-post]:
>> https://lore.kernel.org/all/[email protected]/
>>
>> It is expected to soon be interegrated into a 6.1.y kernel.
>>
>> But maybe it's something else. I CCed the involved people, they might
>> know.
>
> We applied f72f4312d43883 to the current Debian kernel (based on
> 6.1.55) but it didn't help, same stack trace.
> Looking at the description, __bch_btree_node_alloc() should never be
> able to return NULL anyway after
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=7ecea5ce3dc17339c280c75b58ac93d8c8620d9f
> But I didn't verify all callers, so this might still be correct, if
> it's not always initialized with the return value of
> __bch_btree_node_alloc().
>
> Anyway, I think we fixed it by applying this:
>
> diff -Naurp a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
> --- a/drivers/md/bcache/btree.c 2023-09-23 11:11:13.000000000 +0200
> +++ b/drivers/md/bcache/btree.c 2023-11-24 13:13:09.840013759 +0100
> @@ -1489,7 +1489,7 @@ out_nocoalesce:
> bch_keylist_free(&keylist);
>
> for (i = 0; i < nodes; i++)
> - if (!IS_ERR(new_nodes[i])) {
> + if (!IS_ERR_OR_NULL(new_nodes[i])) {
> btree_node_free(new_nodes[i]);
> rw_unlock(true, new_nodes[i]);
> }
>

The above change is what commit f72f4312d43883 ("bcache: replace a mistaken IS_ERR() by IS_ERR_OR_NULL() in btree_gc_coalesce()” does.

Although the above patch is suggested to go into 6.5+ kernel, for this condition it should go into all stable kernels where commit 028ddcac477b69 ("bcache: Remove unnecessary NULL point check in node allocations”) were merged into.

Coly Li


> --
>
> That seems to run stable now. I suppose the culprit is here:
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/md/bcache/btree.c?h=v6.1.55#n1448
>
> new_nodes[0] = NULL;
>
> for (i = 0; i < nodes; i++) {
> if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b-
>> key)))
> goto out_nocoalesce;
>
>
> So if __bch_keylist_realloc() succeeds, then btree_node_free() will be
> called with new_nodes[0] which is NULL.
>
> This is still the same in mainline:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/md/bcache/btree.c?id=31f5b956a197d4ec25c8a07cb3a2ab69d0c0b82f#n1481
>
>
>
>>
>> Ciao, Thorsten
>>
>>> to make sure the systems don't suddenly get stuck.
>>>
>>> 1. Kernel 6.6.2-arch1-1 on Dell Latitude:
>>>
>>> [16816.214942] BUG: kernel NULL pointer dereference, address:
>>> 0000000000000080
>>> [16816.214948] #PF: supervisor read access in kernel mode
>>> [16816.214951] #PF: error_code(0x0000) - not-present page
>>> [16816.214953] PGD 0 P4D 0 [16816.214956] Oops: 0000 [#1] PREEMPT
>>> SMP NOPTI
>>> [16816.214960] CPU: 7 PID: 83416 Comm: bcache_gc Tainted:
>>> P
>>> OE 6.6.2-arch1-1 #1 11215f9ba7ddfb51644674a5b2ced71612c62fe9
>>> [16816.214964] Hardware name: Dell Inc. Latitude 5431/06F77M, BIOS
>>> 1.17.0 09/21/2023
>>> [16816.214965] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
>>> [16816.214999] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90
>>> 90 90
>>> 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f
>>> 44 00
>>> 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00
>>> 75
>>> [16816.215001] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
>>> [16816.215004] RAX: 0000000000000001 RBX: 0000000000000000 RCX:
>>> ffff888515ce0670
>>> [16816.215006] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI:
>>> 0000000000000000
>>> [16816.215007] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09:
>>> 00000000013ffde8
>>> [16816.215009] R10: 0000000000000000 R11: ffffc9000061b000 R12:
>>> ffffc90021777e40
>>> [16816.215010] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15:
>>> ffff88819476c000
>>> [16816.215011] FS: 0000000000000000(0000)
>>> GS:ffff88886fdc0000(0000)
>>> knlGS:0000000000000000
>>> [16816.215013] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [16816.215015] CR2: 0000000000000080 CR3: 0000000294a20000 CR4:
>>> 0000000000f50ee0
>>> [16816.215017] PKRU: 55555554
>>> [16816.215018] Call Trace:
>>> [16816.215021] <TASK>
>>> [16816.215024] ? __die+0x23/0x70
>>> [16816.215030] ? page_fault_oops+0x171/0x4e0
>>> [16816.215035] ? __pfx_bch_ptr_bad+0x10/0x10 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215059] ? exc_page_fault+0x7f/0x180
>>> [16816.215065] ? asm_exc_page_fault+0x26/0x30
>>> [16816.215070] ? btree_node_free+0xf/0x160 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215095] ? btree_node_free+0xa3/0x160 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215118] btree_gc_coalesce+0x2a7/0x890 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215144] ? bch_extent_bad+0x81/0x190 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215172] btree_gc_recurse+0x130/0x390 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215197] ? btree_gc_mark_node+0x72/0x240 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215221] bch_btree_gc+0x4b6/0x620 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215246] ? __pfx_autoremove_wake_function+0x10/0x10
>>> [16816.215250] ? __pfx_bch_gc_thread+0x10/0x10 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215272] bch_gc_thread+0x139/0x190 [bcache
>>> 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
>>> [16816.215295] ? __pfx_autoremove_wake_function+0x10/0x10
>>> [16816.215298] kthread+0xe5/0x120
>>> [16816.215302] ? __pfx_kthread+0x10/0x10
>>> [16816.215306] ret_from_fork+0x31/0x50
>>> [16816.215309] ? __pfx_kthread+0x10/0x10
>>> [16816.215312] ret_from_fork_asm+0x1b/0x30
>>> [16816.215318] </TASK>
>>> [16816.215319] Modules linked in: bcache tun ccm rfcomm
>>> snd_seq_dummy
>>> snd_hrtimer snd_seq nvidia(POE) typec_displayport cmac algif_hash
>>> algif_skcipher af_alg bnep hid_sensor_custom hid_sensor_hub
>>> intel_ishtp_hid snd_hda_codec_hdmi snd_sof_pci_intel_tgl
>>> snd_sof_intel_hda_common soundwire_intel snd_sof_intel_hda_mlink
>>> soundwire_cadence snd_sof_intel_hda snd_sof_pci snd_sof_xtensa_dsp
>>> snd_sof snd_sof_utils intel_uncore_frequency
>>> intel_uncore_frequency_common snd_ctl_led snd_soc_hdac_hda
>>> r8153_ecm
>>> snd_hda_ext_core iwlmvm cdc_ether snd_soc_acpi_intel_match usbnet
>>> snd_soc_acpi soundwire_generic_allocation soundwire_bus
>>> snd_soc_core
>>> x86_pkg_temp_thermal snd_compress snd_hda_codec_realtek
>>> intel_powerclamp
>>> ac97_bus snd_hda_codec_generic dell_rbtn coretemp btusb
>>> snd_pcm_dmaengine snd_usb_audio mac80211 btrtl snd_hda_intel
>>> kvm_intel
>>> btintel snd_intel_dspcfg snd_intel_sdw_acpi snd_usbmidi_lib btbcm
>>> dell_laptop snd_ump btmtk libarc4 snd_hda_codec uvcvideo kvm
>>> snd_rawmidi
>>> bluetooth snd_hda_core videobuf2_vmalloc hid_multitouch iwlwifi
>>> [16816.215367] dell_wmi snd_hwdep iTCO_wdt snd_seq_device uvc
>>> nls_iso8859_1 videobuf2_memops dell_smbios intel_pmc_bxt mei_hdcp
>>> mei_pxp spi_nor snd_pcm processor_thermal_device_pci r8152
>>> videobuf2_v4l2 dell_wmi_sysman irqbypass intel_rapl_msr dcdbas vfat
>>> iTCO_vendor_support fat rapl intel_cstate intel_uncore psmouse
>>> pcspkr
>>> dell_wmi_ddv firmware_attributes_class ledtrig_audio
>>> videobuf2_common
>>> ucsi_acpi dell_wmi_descriptor processor_thermal_device mousedev
>>> ecdh_generic snd_timer mii joydev mtd wmi_bmof e1000e cfg80211
>>> processor_thermal_rfim mei_me intel_lpss_pci i2c_i801 snd
>>> processor_thermal_mbox typec_ucsi intel_ish_ipc intel_lpss mei
>>> soundcore
>>> i2c_smbus processor_thermal_rapl rfkill thunderbolt typec idma64
>>> intel_ishtp roles intel_rapl_common igen6_edac i2c_hid_acpi
>>> int3403_thermal i2c_hid int340x_thermal_zone intel_hid
>>> int3400_thermal
>>> acpi_thermal_rel sparse_keymap acpi_tad acpi_pad mac_hid
>>> vboxnetflt(OE)
>>> vboxnetadp(OE) vboxdrv(OE) v4l2loopback(OE) videodev mc i2c_dev
>>> crypto_user fuse loop ip_tables x_tables ext4
>>> [16816.215420] crc32c_generic crc16 mbcache jbd2 dm_crypt cbc
>>> encrypted_keys trusted asn1_encoder tee usbhid i915 dm_mod
>>> crct10dif_pclmul crc32_pclmul crc32c_intel polyval_clmulni
>>> i2c_algo_bit
>>> polyval_generic serio_raw rtsx_pci_sdmmc drm_buddy gf128mul atkbd
>>> ghash_clmulni_intel ttm mmc_core sha512_ssse3 libps2 vivaldi_fmap
>>> intel_gtt aesni_intel nvme crypto_simd drm_display_helper video
>>> nvme_core cryptd spi_intel_pci rtsx_pci spi_intel i8042 xhci_pci
>>> cec
>>> nvme_common xhci_pci_renesas serio wmi
>>> [16816.215451] CR2: 0000000000000080
>>> [16816.215453] ---[ end trace 0000000000000000 ]---
>>> [16816.215455] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
>>> [16816.215478] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90
>>> 90 90
>>> 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f
>>> 44 00
>>> 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00
>>> 75
>>> [16816.215480] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
>>> [16816.215481] RAX: 0000000000000001 RBX: 0000000000000000 RCX:
>>> ffff888515ce0670
>>> [16816.215483] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI:
>>> 0000000000000000
>>> [16816.215484] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09:
>>> 00000000013ffde8
>>> [16816.215486] R10: 0000000000000000 R11: ffffc9000061b000 R12:
>>> ffffc90021777e40
>>> [16816.215487] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15:
>>> ffff88819476c000
>>> [16816.215488] FS: 0000000000000000(0000)
>>> GS:ffff88886fdc0000(0000)
>>> knlGS:0000000000000000
>>> [16816.215490] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [16816.215492] CR2: 0000000000000080 CR3: 0000000294a20000 CR4:
>>> 0000000000f50ee0
>>> [16816.215493] PKRU: 55555554
>>> [16816.215494] note: bcache_gc[83416] exited with irqs disabled
>>>
>>> 2. Kernel 6.1.55 (Debian 6.1.0-13) on HPE Gen11:
>>>
>>> [60654.670443] BUG: kernel NULL pointer dereference, address:
>>> 0000000000000080
>>> [60654.677474] #PF: supervisor read access in kernel mode
>>> [60654.682651] #PF: error_code(0x0000) - not-present page
>>> [60654.687825] PGD 0 [60654.689852] Oops: 0000 [#1] PREEMPT SMP
>>> NOPTI
>>> [60654.694240] CPU: 16 PID: 146330 Comm: bcache_gc Tainted:
>>> G
>>> W 6.1.0-13-amd64 #1 Debian 6.1.55-1
>>> [60654.704399] Hardware name: HPE ProLiant DL380 Gen11/ProLiant
>>> DL380
>>> Gen11, BIOS 1.48 10/19/2023
>>> [60654.713071] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
>>> [60654.718437] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc
>>> 66 66
>>> 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f
>>> 44 00
>>> 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48
>>> 8d
>>> [60654.737342] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
>>> [60654.742604] RAX: 0000000080000000 RBX: 0000000000000000 RCX:
>>> 0000000000000000
>>> [60654.749790] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI:
>>> 0000000000000000
>>> [60654.756975] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09:
>>> ff2971b8de800000
>>> [60654.764536] R10: 0000000000000000 R11: ff77daed34a4d000 R12:
>>> ff77daed34cc3e60
>>> [60654.771987] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15:
>>> ff2971d851096400
>>> [60654.779410] FS: 0000000000000000(0000)
>>> GS:ff2971f7bf400000(0000)
>>> knlGS:0000000000000000
>>> [60654.787784] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [60654.793794] CR2: 0000000000000080 CR3: 0000000150610002 CR4:
>>> 0000000000771ee0
>>> [60654.801203] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
>>> 0000000000000000
>>> [60654.808609] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7:
>>> 0000000000000400
>>> [60654.816009] PKRU: 55555554
>>> [60654.818949] Call Trace:
>>> [60654.821623] <TASK>
>>> [60654.823950] ? __die_body.cold+0x1a/0x1f
>>> [60654.828110] ? page_fault_oops+0xd2/0x2b0
>>> [60654.832352] ? exc_page_fault+0x70/0x170
>>> [60654.836505] ? asm_exc_page_fault+0x22/0x30
>>> [60654.840922] ? btree_node_free+0xf/0x160 [bcache]
>>> [60654.845863] ? up_write+0x32/0x60
>>> [60654.849396] btree_gc_coalesce+0x2aa/0x890 [bcache]
>>> [60654.854512] ? bch_extent_bad+0x70/0x170 [bcache]
>>> [60654.859452] btree_gc_recurse+0x130/0x390 [bcache]
>>> [60654.864475] ? btree_gc_mark_node+0x72/0x230 [bcache]
>>> [60654.869758] bch_btree_gc+0x5da/0x600 [bcache]
>>> [60654.874428] ? cpuusage_read+0x10/0x10
>>> [60654.878390] ? bch_btree_gc+0x600/0x600 [bcache]
>>> [60654.883232] bch_gc_thread+0x135/0x180 [bcache]
>>> [60654.887986] ? cpuusage_read+0x10/0x10
>>> [60654.891944] kthread+0xe6/0x110
>>> [60654.895290] ? kthread_complete_and_exit+0x20/0x20
>>> [60654.900296] ret_from_fork+0x1f/0x30
>>> [60654.904079] </TASK>
>>> [60654.906455] Modules linked in: bonding tls cfg80211 rfkill
>>> intel_rapl_msr intel_rapl_common intel_uncore_frequency
>>> intel_uncore_frequency_common i10nm_edac nfit binfmt_misc libnvdimm
>>> x86_pkg_temp_thermal intel_powerclamp ipt_REJECT nf_reject_ipv4
>>> coretemp
>>> xt_comment nft_compat nf_tables nfnetlink nls_ascii nls_cp437
>>> kvm_intel
>>> vfat ipmi_ssif fat kvm irqbypass ghash_clmulni_intel sha512_ssse3
>>> sha512_generic aesni_intel crypto_simd cryptd mgag200
>>> drm_shmem_helper
>>> pmt_telemetry pmt_crashlog rapl intel_cstate acpi_ipmi evdev
>>> intel_sdsi
>>> pmt_class idxd hpwdt mei_me isst_if_mbox_pci isst_if_mmio
>>> drm_kms_helper
>>> intel_uncore pcspkr isst_if_common mei watchdog hpilo i2c_algo_bit
>>> ipmi_si idxd_bus acpi_tad intel_vsec sg acpi_power_meter button
>>> ipmi_devintf ipmi_msghandler loop fuse efi_pstore drm configfs
>>> efivarfs
>>> ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 btrfs
>>> blake2b_generic
>>> xor raid6_pq zstd_compress libcrc32c crc32c_generic ses enclosure
>>> bcache
>>> sd_mod scsi_transport_sas dm_mod nvme
>>> [60654.906508] nvme_core xhci_pci t10_pi megaraid_sas ehci_pci
>>> xhci_hcd
>>> ehci_hcd crc64_rocksoft crc64 tg3 crc_t10dif scsi_mod usbcore
>>> crct10dif_generic crc32_pclmul crc32c_intel crct10dif_pclmul libphy
>>> scsi_common usb_common crct10dif_common wmi
>>> [60655.017712] CR2: 0000000000000080
>>> [60655.021262] ---[ end trace 0000000000000000 ]---
>>> [60655.173744] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
>>> [60655.179337] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc
>>> 66 66
>>> 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f
>>> 44 00
>>> 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48
>>> 8d
>>> [60655.198649] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
>>> [60655.204121] RAX: 0000000080000000 RBX: 0000000000000000 RCX:
>>> 0000000000000000
>>> [60655.211515] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI:
>>> 0000000000000000
>>> [60655.218908] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09:
>>> ff2971b8de800000
>>> [60655.226302] R10: 0000000000000000 R11: ff77daed34a4d000 R12:
>>> ff77daed34cc3e60
>>> [60655.233696] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15:
>>> ff2971d851096400
>>> [60655.241086] FS: 0000000000000000(0000)
>>> GS:ff2971f7bf400000(0000)
>>> knlGS:0000000000000000
>>> [60655.249438] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [60655.255432] CR2: 0000000000000080 CR3: 0000000150610002 CR4:
>>> 0000000000771ee0
>>> [60655.262825] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
>>> 0000000000000000
>>> [60655.270218] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7:
>>> 0000000000000400
>>> [60655.277607] PKRU: 55555554
>>> [60655.280543] note: bcache_gc[146330] exited with irqs disabled
>>>
>>> Reproducer for us:
>>>
>>> dd if=/dev/zero of=loop0 bs=1M count=1024
>>> dd if=/dev/zero of=loop1 bs=1M count=10240
>>> losetup loop0 loop0
>>> losetup loop1 loop1
>>> make-bcache -C /dev/loop0 -B /dev/loop1 --writeback
>>> mkfs.ext4 /dev/bcache0
>>> mount /dev/bcache0 /mnt
>>>
>>> Then run fio with:
>>>
>>> [global]
>>> bs=4k
>>> ioengine=libaio
>>> iodepth=4
>>> size=8g
>>> direct=1
>>> runtime=60
>>> directory=/mnt
>>> filename=ssd.test.file
>>>
>>> [seq-write]
>>> rw=write
>>> stonewall
>>>
>>> [rand-write]
>>> rw=randwrite
>>> stonewall
>>>
>>> [seq-read]
>>> rw=read
>>> stonewall
>>>
>>> [rand-read]
>>> rw=randread
>>> stonewall
>>>
>>>
>>> Cheers,
>>> Stefan

2023-11-24 13:55:22

by Markus Weippert

Subject: Re: bcache: kernel NULL pointer dereference since 6.1.39

On Fri, 2023-11-24 at 21:46 +0800, Coly Li wrote:
>
>
> > 2023年11月24日 21:29，Markus Weippert <[email protected]> 写道：
> >
> > > On 23.11.23 14:53, Stefan Förster wrote:
> > > >
> > > > starting with kernel 6.1.39, we see the following error message
> > > > with
> > > > heavy I/O loads. We needed to revert
> > >
> > > Thx for the report. I assume that problem still occurs with the
> > > latest
> > > 6.1.y kernel?
> > >
> > > > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=68118c339c6e1e16ae017bef160dbe28a27ae9c8
> > >
> > > FWIW, that is mainline commit 028ddcac477b69 ("bcache: Remove
> > > unnecessary NULL point check in node allocations") [v6.5-rc1].
> > >
> > > Did a quick check and noticed a fix for that change was recently
> > > mainlined as f72f4312d43883 ("bcache: replace a mistaken IS_ERR()
> > > by
> > > IS_ERR_OR_NULL() in btree_gc_coalesce()") [v6.7-rc2-post]:
> > > https://lore.kernel.org/all/[email protected]/
> > >
> > > It is expected to soon be interegrated into a 6.1.y kernel.
> > >
> > > But maybe it's something else. I CCed the involved people, they
> > > might
> > > know.
> >
> > We applied f72f4312d43883 to the current Debian kernel (based on
> > 6.1.55) but it didn't help, same stack trace.
> > Looking at the description, __bch_btree_node_alloc() should never
> > be
> > able to return NULL anyway after
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=7ecea5ce3dc17339c280c75b58ac93d8c8620d9f
> > But I didn't verify all callers, so this might still be correct, if
> > it's not always initialized with the return value of
> > __bch_btree_node_alloc().
> >
> > Anyway, I think we fixed it by applying this:
> >
> > diff -Naurp a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
> > --- a/drivers/md/bcache/btree.c 2023-09-23 11:11:13.000000000 +0200
> > +++ b/drivers/md/bcache/btree.c 2023-11-24 13:13:09.840013759 +0100
> > @@ -1489,7 +1489,7 @@ out_nocoalesce:
> > bch_keylist_free(&keylist);
> >
> > for (i = 0; i < nodes; i++)
> > - if (!IS_ERR(new_nodes[i])) {
> > + if (!IS_ERR_OR_NULL(new_nodes[i])) {
> > btree_node_free(new_nodes[i]);
> > rw_unlock(true, new_nodes[i]);
> > }
> >
>
> The above change is what commit f72f4312d43883 ("bcache: replace a
> mistaken IS_ERR() by IS_ERR_OR_NULL() in btree_gc_coalesce()” does.

But f72f4312d43883 reverts @@ -1340,7 +1340,7 @@, while the patch we
applied reverts @@ -1487,7 +1487,7 @@ instead.
Applying f72f4312d43883 didn't help for us.

>
> Although the above patch is suggested to go into 6.5+ kernel, for
> this condition it should go into all stable kernels where commit
> 028ddcac477b69 ("bcache: Remove unnecessary NULL point check in node
> allocations”) were merged into.
>
> Coly Li
>
>
> > --
> >
> > That seems to run stable now. I suppose the culprit is here:
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/md/bcache/btree.c?h=v6.1.55#n1448
> >
> > new_nodes[0] = NULL;
> >
> > for (i = 0; i < nodes; i++) {
> > if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b-
> > > key)))
> > goto out_nocoalesce;
> >
> >
> > So if __bch_keylist_realloc() succeeds, then btree_node_free() will
> > be
> > called with new_nodes[0] which is NULL.
> >
> > This is still the same in mainline:
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/md/bcache/btree.c?id=31f5b956a197d4ec25c8a07cb3a2ab69d0c0b82f#n1481
> >
> >
> >
> > >
> > > Ciao, Thorsten
> > >
> > > > to make sure the systems don't suddenly get stuck.
> > > >
> > > > 1. Kernel 6.6.2-arch1-1 on Dell Latitude:
> > > >
> > > > [16816.214942] BUG: kernel NULL pointer dereference, address:
> > > > 0000000000000080
> > > > [16816.214948] #PF: supervisor read access in kernel mode
> > > > [16816.214951] #PF: error_code(0x0000) - not-present page
> > > > [16816.214953] PGD 0 P4D 0 [16816.214956] Oops: 0000 [#1]
> > > > PREEMPT
> > > > SMP NOPTI
> > > > [16816.214960] CPU: 7 PID: 83416 Comm: bcache_gc Tainted:
> > > > P         
> > > > OE      6.6.2-arch1-1 #1
> > > > 11215f9ba7ddfb51644674a5b2ced71612c62fe9
> > > > [16816.214964] Hardware name: Dell Inc. Latitude 5431/06F77M,
> > > > BIOS
> > > > 1.17.0 09/21/2023
> > > > [16816.214965] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> > > > [16816.214999] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90
> > > > 90
> > > > 90 90
> > > > 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f
> > > > 1f
> > > > 44 00
> > > > 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3
> > > > 00 00
> > > > 75
> > > > [16816.215001] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
> > > > [16816.215004] RAX: 0000000000000001 RBX: 0000000000000000 RCX:
> > > > ffff888515ce0670
> > > > [16816.215006] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI:
> > > > 0000000000000000
> > > > [16816.215007] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09:
> > > > 00000000013ffde8
> > > > [16816.215009] R10: 0000000000000000 R11: ffffc9000061b000 R12:
> > > > ffffc90021777e40
> > > > [16816.215010] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15:
> > > > ffff88819476c000
> > > > [16816.215011] FS:  0000000000000000(0000)
> > > > GS:ffff88886fdc0000(0000)
> > > > knlGS:0000000000000000
> > > > [16816.215013] CS:  0010 DS: 0000 ES: 0000 CR0:
> > > > 0000000080050033
> > > > [16816.215015] CR2: 0000000000000080 CR3: 0000000294a20000 CR4:
> > > > 0000000000f50ee0
> > > > [16816.215017] PKRU: 55555554
> > > > [16816.215018] Call Trace:
> > > > [16816.215021]  <TASK>
> > > > [16816.215024]  ? __die+0x23/0x70
> > > > [16816.215030]  ? page_fault_oops+0x171/0x4e0
> > > > [16816.215035]  ? __pfx_bch_ptr_bad+0x10/0x10 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215059]  ? exc_page_fault+0x7f/0x180
> > > > [16816.215065]  ? asm_exc_page_fault+0x26/0x30
> > > > [16816.215070]  ? btree_node_free+0xf/0x160 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215095]  ? btree_node_free+0xa3/0x160 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215118]  btree_gc_coalesce+0x2a7/0x890 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215144]  ? bch_extent_bad+0x81/0x190 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215172]  btree_gc_recurse+0x130/0x390 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215197]  ? btree_gc_mark_node+0x72/0x240 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215221]  bch_btree_gc+0x4b6/0x620 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215246]  ? __pfx_autoremove_wake_function+0x10/0x10
> > > > [16816.215250]  ? __pfx_bch_gc_thread+0x10/0x10 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215272]  bch_gc_thread+0x139/0x190 [bcache
> > > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6]
> > > > [16816.215295]  ? __pfx_autoremove_wake_function+0x10/0x10
> > > > [16816.215298]  kthread+0xe5/0x120
> > > > [16816.215302]  ? __pfx_kthread+0x10/0x10
> > > > [16816.215306]  ret_from_fork+0x31/0x50
> > > > [16816.215309]  ? __pfx_kthread+0x10/0x10
> > > > [16816.215312]  ret_from_fork_asm+0x1b/0x30
> > > > [16816.215318]  </TASK>
> > > > [16816.215319] Modules linked in: bcache tun ccm rfcomm
> > > > snd_seq_dummy
> > > > snd_hrtimer snd_seq nvidia(POE) typec_displayport cmac
> > > > algif_hash
> > > > algif_skcipher af_alg bnep hid_sensor_custom hid_sensor_hub
> > > > intel_ishtp_hid snd_hda_codec_hdmi snd_sof_pci_intel_tgl
> > > > snd_sof_intel_hda_common soundwire_intel
> > > > snd_sof_intel_hda_mlink
> > > > soundwire_cadence snd_sof_intel_hda snd_sof_pci
> > > > snd_sof_xtensa_dsp
> > > > snd_sof snd_sof_utils intel_uncore_frequency
> > > > intel_uncore_frequency_common snd_ctl_led snd_soc_hdac_hda
> > > > r8153_ecm
> > > > snd_hda_ext_core iwlmvm cdc_ether snd_soc_acpi_intel_match
> > > > usbnet
> > > > snd_soc_acpi soundwire_generic_allocation soundwire_bus
> > > > snd_soc_core
> > > > x86_pkg_temp_thermal snd_compress snd_hda_codec_realtek
> > > > intel_powerclamp
> > > > ac97_bus snd_hda_codec_generic dell_rbtn coretemp btusb
> > > > snd_pcm_dmaengine snd_usb_audio mac80211 btrtl snd_hda_intel
> > > > kvm_intel
> > > > btintel snd_intel_dspcfg snd_intel_sdw_acpi snd_usbmidi_lib
> > > > btbcm
> > > > dell_laptop snd_ump btmtk libarc4 snd_hda_codec uvcvideo kvm
> > > > snd_rawmidi
> > > > bluetooth snd_hda_core videobuf2_vmalloc hid_multitouch iwlwifi
> > > > [16816.215367]  dell_wmi snd_hwdep iTCO_wdt snd_seq_device uvc
> > > > nls_iso8859_1 videobuf2_memops dell_smbios intel_pmc_bxt
> > > > mei_hdcp
> > > > mei_pxp spi_nor snd_pcm processor_thermal_device_pci r8152
> > > > videobuf2_v4l2 dell_wmi_sysman irqbypass intel_rapl_msr dcdbas
> > > > vfat
> > > > iTCO_vendor_support fat rapl intel_cstate intel_uncore psmouse
> > > > pcspkr
> > > > dell_wmi_ddv firmware_attributes_class ledtrig_audio
> > > > videobuf2_common
> > > > ucsi_acpi dell_wmi_descriptor processor_thermal_device mousedev
> > > > ecdh_generic snd_timer mii joydev mtd wmi_bmof e1000e cfg80211
> > > > processor_thermal_rfim mei_me intel_lpss_pci i2c_i801 snd
> > > > processor_thermal_mbox typec_ucsi intel_ish_ipc intel_lpss mei
> > > > soundcore
> > > > i2c_smbus processor_thermal_rapl rfkill thunderbolt typec
> > > > idma64
> > > > intel_ishtp roles intel_rapl_common igen6_edac i2c_hid_acpi
> > > > int3403_thermal i2c_hid int340x_thermal_zone intel_hid
> > > > int3400_thermal
> > > > acpi_thermal_rel sparse_keymap acpi_tad acpi_pad mac_hid
> > > > vboxnetflt(OE)
> > > > vboxnetadp(OE) vboxdrv(OE) v4l2loopback(OE) videodev mc i2c_dev
> > > > crypto_user fuse loop ip_tables x_tables ext4
> > > > [16816.215420]  crc32c_generic crc16 mbcache jbd2 dm_crypt cbc
> > > > encrypted_keys trusted asn1_encoder tee usbhid i915 dm_mod
> > > > crct10dif_pclmul crc32_pclmul crc32c_intel polyval_clmulni
> > > > i2c_algo_bit
> > > > polyval_generic serio_raw rtsx_pci_sdmmc drm_buddy gf128mul
> > > > atkbd
> > > > ghash_clmulni_intel ttm mmc_core sha512_ssse3 libps2
> > > > vivaldi_fmap
> > > > intel_gtt aesni_intel nvme crypto_simd drm_display_helper video
> > > > nvme_core cryptd spi_intel_pci rtsx_pci spi_intel i8042
> > > > xhci_pci
> > > > cec
> > > > nvme_common xhci_pci_renesas serio wmi
> > > > [16816.215451] CR2: 0000000000000080
> > > > [16816.215453] ---[ end trace 0000000000000000 ]---
> > > > [16816.215455] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> > > > [16816.215478] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90
> > > > 90
> > > > 90 90
> > > > 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f
> > > > 1f
> > > > 44 00
> > > > 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3
> > > > 00 00
> > > > 75
> > > > [16816.215480] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207
> > > > [16816.215481] RAX: 0000000000000001 RBX: 0000000000000000 RCX:
> > > > ffff888515ce0670
> > > > [16816.215483] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI:
> > > > 0000000000000000
> > > > [16816.215484] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09:
> > > > 00000000013ffde8
> > > > [16816.215486] R10: 0000000000000000 R11: ffffc9000061b000 R12:
> > > > ffffc90021777e40
> > > > [16816.215487] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15:
> > > > ffff88819476c000
> > > > [16816.215488] FS:  0000000000000000(0000)
> > > > GS:ffff88886fdc0000(0000)
> > > > knlGS:0000000000000000
> > > > [16816.215490] CS:  0010 DS: 0000 ES: 0000 CR0:
> > > > 0000000080050033
> > > > [16816.215492] CR2: 0000000000000080 CR3: 0000000294a20000 CR4:
> > > > 0000000000f50ee0
> > > > [16816.215493] PKRU: 55555554
> > > > [16816.215494] note: bcache_gc[83416] exited with irqs disabled
> > > >
> > > > 2. Kernel 6.1.55 (Debian 6.1.0-13) on HPE Gen11:
> > > >
> > > > [60654.670443] BUG: kernel NULL pointer dereference, address:
> > > > 0000000000000080
> > > > [60654.677474] #PF: supervisor read access in kernel mode
> > > > [60654.682651] #PF: error_code(0x0000) - not-present page
> > > > [60654.687825] PGD 0 [60654.689852] Oops: 0000 [#1] PREEMPT SMP
> > > > NOPTI
> > > > [60654.694240] CPU: 16 PID: 146330 Comm: bcache_gc Tainted:
> > > > G      
> > > > W          6.1.0-13-amd64 #1  Debian 6.1.55-1
> > > > [60654.704399] Hardware name: HPE ProLiant DL380 Gen11/ProLiant
> > > > DL380
> > > > Gen11, BIOS 1.48 10/19/2023
> > > > [60654.713071] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> > > > [60654.718437] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc
> > > > cc
> > > > 66 66
> > > > 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f
> > > > 1f
> > > > 44 00
> > > > 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00
> > > > 00 48
> > > > 8d
> > > > [60654.737342] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
> > > > [60654.742604] RAX: 0000000080000000 RBX: 0000000000000000 RCX:
> > > > 0000000000000000
> > > > [60654.749790] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI:
> > > > 0000000000000000
> > > > [60654.756975] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09:
> > > > ff2971b8de800000
> > > > [60654.764536] R10: 0000000000000000 R11: ff77daed34a4d000 R12:
> > > > ff77daed34cc3e60
> > > > [60654.771987] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15:
> > > > ff2971d851096400
> > > > [60654.779410] FS:  0000000000000000(0000)
> > > > GS:ff2971f7bf400000(0000)
> > > > knlGS:0000000000000000
> > > > [60654.787784] CS:  0010 DS: 0000 ES: 0000 CR0:
> > > > 0000000080050033
> > > > [60654.793794] CR2: 0000000000000080 CR3: 0000000150610002 CR4:
> > > > 0000000000771ee0
> > > > [60654.801203] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> > > > 0000000000000000
> > > > [60654.808609] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7:
> > > > 0000000000000400
> > > > [60654.816009] PKRU: 55555554
> > > > [60654.818949] Call Trace:
> > > > [60654.821623]  <TASK>
> > > > [60654.823950]  ? __die_body.cold+0x1a/0x1f
> > > > [60654.828110]  ? page_fault_oops+0xd2/0x2b0
> > > > [60654.832352]  ? exc_page_fault+0x70/0x170
> > > > [60654.836505]  ? asm_exc_page_fault+0x22/0x30
> > > > [60654.840922]  ? btree_node_free+0xf/0x160 [bcache]
> > > > [60654.845863]  ? up_write+0x32/0x60
> > > > [60654.849396]  btree_gc_coalesce+0x2aa/0x890 [bcache]
> > > > [60654.854512]  ? bch_extent_bad+0x70/0x170 [bcache]
> > > > [60654.859452]  btree_gc_recurse+0x130/0x390 [bcache]
> > > > [60654.864475]  ? btree_gc_mark_node+0x72/0x230 [bcache]
> > > > [60654.869758]  bch_btree_gc+0x5da/0x600 [bcache]
> > > > [60654.874428]  ? cpuusage_read+0x10/0x10
> > > > [60654.878390]  ? bch_btree_gc+0x600/0x600 [bcache]
> > > > [60654.883232]  bch_gc_thread+0x135/0x180 [bcache]
> > > > [60654.887986]  ? cpuusage_read+0x10/0x10
> > > > [60654.891944]  kthread+0xe6/0x110
> > > > [60654.895290]  ? kthread_complete_and_exit+0x20/0x20
> > > > [60654.900296]  ret_from_fork+0x1f/0x30
> > > > [60654.904079]  </TASK>
> > > > [60654.906455] Modules linked in: bonding tls cfg80211 rfkill
> > > > intel_rapl_msr intel_rapl_common intel_uncore_frequency
> > > > intel_uncore_frequency_common i10nm_edac nfit binfmt_misc
> > > > libnvdimm
> > > > x86_pkg_temp_thermal intel_powerclamp ipt_REJECT nf_reject_ipv4
> > > > coretemp
> > > > xt_comment nft_compat nf_tables nfnetlink nls_ascii nls_cp437
> > > > kvm_intel
> > > > vfat ipmi_ssif fat kvm irqbypass ghash_clmulni_intel
> > > > sha512_ssse3
> > > > sha512_generic aesni_intel crypto_simd cryptd mgag200
> > > > drm_shmem_helper
> > > > pmt_telemetry pmt_crashlog rapl intel_cstate acpi_ipmi evdev
> > > > intel_sdsi
> > > > pmt_class idxd hpwdt mei_me isst_if_mbox_pci isst_if_mmio
> > > > drm_kms_helper
> > > > intel_uncore pcspkr isst_if_common mei watchdog hpilo
> > > > i2c_algo_bit
> > > > ipmi_si idxd_bus acpi_tad intel_vsec sg acpi_power_meter button
> > > > ipmi_devintf ipmi_msghandler loop fuse efi_pstore drm configfs
> > > > efivarfs
> > > > ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 btrfs
> > > > blake2b_generic
> > > > xor raid6_pq zstd_compress libcrc32c crc32c_generic ses
> > > > enclosure
> > > > bcache
> > > > sd_mod scsi_transport_sas dm_mod nvme
> > > > [60654.906508]  nvme_core xhci_pci t10_pi megaraid_sas ehci_pci
> > > > xhci_hcd
> > > > ehci_hcd crc64_rocksoft crc64 tg3 crc_t10dif scsi_mod usbcore
> > > > crct10dif_generic crc32_pclmul crc32c_intel crct10dif_pclmul
> > > > libphy
> > > > scsi_common usb_common crct10dif_common wmi
> > > > [60655.017712] CR2: 0000000000000080
> > > > [60655.021262] ---[ end trace 0000000000000000 ]---
> > > > [60655.173744] RIP: 0010:btree_node_free+0xf/0x160 [bcache]
> > > > [60655.179337] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc
> > > > cc
> > > > 66 66
> > > > 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f
> > > > 1f
> > > > 44 00
> > > > 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00
> > > > 00 48
> > > > 8d
> > > > [60655.198649] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207
> > > > [60655.204121] RAX: 0000000080000000 RBX: 0000000000000000 RCX:
> > > > 0000000000000000
> > > > [60655.211515] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI:
> > > > 0000000000000000
> > > > [60655.218908] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09:
> > > > ff2971b8de800000
> > > > [60655.226302] R10: 0000000000000000 R11: ff77daed34a4d000 R12:
> > > > ff77daed34cc3e60
> > > > [60655.233696] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15:
> > > > ff2971d851096400
> > > > [60655.241086] FS:  0000000000000000(0000)
> > > > GS:ff2971f7bf400000(0000)
> > > > knlGS:0000000000000000
> > > > [60655.249438] CS:  0010 DS: 0000 ES: 0000 CR0:
> > > > 0000000080050033
> > > > [60655.255432] CR2: 0000000000000080 CR3: 0000000150610002 CR4:
> > > > 0000000000771ee0
> > > > [60655.262825] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> > > > 0000000000000000
> > > > [60655.270218] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7:
> > > > 0000000000000400
> > > > [60655.277607] PKRU: 55555554
> > > > [60655.280543] note: bcache_gc[146330] exited with irqs
> > > > disabled
> > > >
> > > > Reproducer for us:
> > > >
> > > > dd if=/dev/zero of=loop0 bs=1M count=1024
> > > > dd if=/dev/zero of=loop1 bs=1M count=10240
> > > > losetup loop0 loop0
> > > > losetup loop1 loop1
> > > > make-bcache -C /dev/loop0 -B /dev/loop1 --writeback
> > > > mkfs.ext4 /dev/bcache0
> > > > mount /dev/bcache0 /mnt
> > > >
> > > > Then run fio with:
> > > >
> > > > [global]
> > > > bs=4k
> > > > ioengine=libaio
> > > > iodepth=4
> > > > size=8g
> > > > direct=1
> > > > runtime=60
> > > > directory=/mnt
> > > > filename=ssd.test.file
> > > >
> > > > [seq-write]
> > > > rw=write
> > > > stonewall
> > > >
> > > > [rand-write]
> > > > rw=randwrite
> > > > stonewall
> > > >
> > > > [seq-read]
> > > > rw=read
> > > > stonewall
> > > >
> > > > [rand-read]
> > > > rw=randread
> > > > stonewall
> > > >
> > > >
> > > > Cheers,
> > > > Stefan
>
>

2023-11-24 14:18:23

by Coly Li

Subject: Re: bcache: kernel NULL pointer dereference since 6.1.39

> 2023年11月24日 21:55，Markus Weippert <[email protected]> 写道：
>
> On Fri, 2023-11-24 at 21:46 +0800, Coly Li wrote:
>>
>>
>>> 2023年11月24日 21:29，Markus Weippert <[email protected]> 写道：
>>>
>>>> On 23.11.23 14:53, Stefan Förster wrote:
>>>>>
>>>>> starting with kernel 6.1.39, we see the following error message
>>>>> with
>>>>> heavy I/O loads. We needed to revert
>>>>
>>>> Thx for the report. I assume that problem still occurs with the
>>>> latest
>>>> 6.1.y kernel?
>>>>
>>>>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=68118c339c6e1e16ae017bef160dbe28a27ae9c8
>>>>
>>>> FWIW, that is mainline commit 028ddcac477b69 ("bcache: Remove
>>>> unnecessary NULL point check in node allocations") [v6.5-rc1].
>>>>
>>>> Did a quick check and noticed a fix for that change was recently
>>>> mainlined as f72f4312d43883 ("bcache: replace a mistaken IS_ERR()
>>>> by
>>>> IS_ERR_OR_NULL() in btree_gc_coalesce()") [v6.7-rc2-post]:
>>>> https://lore.kernel.org/all/[email protected]/
>>>>
>>>> It is expected to soon be interegrated into a 6.1.y kernel.
>>>>
>>>> But maybe it's something else. I CCed the involved people, they
>>>> might
>>>> know.
>>>
>>> We applied f72f4312d43883 to the current Debian kernel (based on
>>> 6.1.55) but it didn't help, same stack trace.
>>> Looking at the description, __bch_btree_node_alloc() should never
>>> be
>>> able to return NULL anyway after
>>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=7ecea5ce3dc17339c280c75b58ac93d8c8620d9f
>>> But I didn't verify all callers, so this might still be correct, if
>>> it's not always initialized with the return value of
>>> __bch_btree_node_alloc().
>>>
>>> Anyway, I think we fixed it by applying this:
>>>
>>> diff -Naurp a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
>>> --- a/drivers/md/bcache/btree.c 2023-09-23 11:11:13.000000000 +0200
>>> +++ b/drivers/md/bcache/btree.c 2023-11-24 13:13:09.840013759 +0100
>>> @@ -1489,7 +1489,7 @@ out_nocoalesce:
>>> bch_keylist_free(&keylist);
>>>
>>> for (i = 0; i < nodes; i++)
>>> - if (!IS_ERR(new_nodes[i])) {
>>> + if (!IS_ERR_OR_NULL(new_nodes[i])) {
>>> btree_node_free(new_nodes[i]);
>>> rw_unlock(true, new_nodes[i]);
>>> }
>>>
>>
>> The above change is what commit f72f4312d43883 ("bcache: replace a
>> mistaken IS_ERR() by IS_ERR_OR_NULL() in btree_gc_coalesce()” does.
>
> But f72f4312d43883 reverts @@ -1340,7 +1340,7 @@, while the patch we
> applied reverts @@ -1487,7 +1487,7 @@ instead.
> Applying f72f4312d43883 didn't help for us.
>

OK, I know what you mean. Yes, your fix is necessary too.

Would you like to post patch for your fix?

Thanks.

Coly Li


>>
>> Although the above patch is suggested to go into 6.5+ kernel, for
>> this condition it should go into all stable kernels where commit
>> 028ddcac477b69 ("bcache: Remove unnecessary NULL point check in node
>> allocations”) were merged into.
[snipped]

2023-11-24 19:31:28

by Markus Weippert

Subject: [PATCH] bcache: revert replacing IS_ERR_OR_NULL with IS_ERR

Commit 028ddcac477b ("bcache: Remove unnecessary NULL point check in
node allocations") replaced IS_ERR_OR_NULL by IS_ERR. This leads to a
NULL pointer dereference.

BUG: kernel NULL pointer dereference, address: 0000000000000080
Call Trace:
? __die_body.cold+0x1a/0x1f
? page_fault_oops+0xd2/0x2b0
? exc_page_fault+0x70/0x170
? asm_exc_page_fault+0x22/0x30
? btree_node_free+0xf/0x160 [bcache]
? up_write+0x32/0x60
btree_gc_coalesce+0x2aa/0x890 [bcache]
? bch_extent_bad+0x70/0x170 [bcache]
btree_gc_recurse+0x130/0x390 [bcache]
? btree_gc_mark_node+0x72/0x230 [bcache]
bch_btree_gc+0x5da/0x600 [bcache]
? cpuusage_read+0x10/0x10
? bch_btree_gc+0x600/0x600 [bcache]
bch_gc_thread+0x135/0x180 [bcache]

The relevant code starts with:

new_nodes[0] = NULL;

for (i = 0; i < nodes; i++) {
if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b->key)))
goto out_nocoalesce;
// ...
out_nocoalesce:
// ...
for (i = 0; i < nodes; i++)
if (!IS_ERR(new_nodes[i])) { // IS_ERR_OR_NULL before
028ddcac477b
btree_node_free(new_nodes[i]); // new_nodes[0] is NULL
rw_unlock(true, new_nodes[i]);
}

This patch replaces IS_ERR() by IS_ERR_OR_NULL() to fix this.

Fixes: 028ddcac477b ("bcache: Remove unnecessary NULL point check in
node allocations")
Link:
https://lore.kernel.org/all/[email protected]/
Cc: [email protected]
Cc: Zheng Wang <[email protected]>
Cc: Coly Li <[email protected]>
Signed-off-by: Markus Weippert <[email protected]>

---
drivers/md/bcache/btree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index de3019972..261596791 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -1522,7 +1522,7 @@ static int btree_gc_coalesce(struct btree *b,
struct btree_op *op,
bch_keylist_free(&keylist);

for (i = 0; i < nodes; i++)
- if (!IS_ERR(new_nodes[i])) {
+ if (!IS_ERR_OR_NULL(new_nodes[i])) {
btree_node_free(new_nodes[i]);
rw_unlock(true, new_nodes[i]);
}
--

2023-11-27 16:12:38

by Jens Axboe

Subject: Re: [PATCH] bcache: revert replacing IS_ERR_OR_NULL with IS_ERR

On Fri, 24 Nov 2023 16:14:37 +0100, Markus Weippert wrote:
> Commit 028ddcac477b ("bcache: Remove unnecessary NULL point check in
> node allocations") replaced IS_ERR_OR_NULL by IS_ERR. This leads to a
> NULL pointer dereference.
>
> BUG: kernel NULL pointer dereference, address: 0000000000000080
> Call Trace:
> ? __die_body.cold+0x1a/0x1f
> ? page_fault_oops+0xd2/0x2b0
> ? exc_page_fault+0x70/0x170
> ? asm_exc_page_fault+0x22/0x30
> ? btree_node_free+0xf/0x160 [bcache]
> ? up_write+0x32/0x60
> btree_gc_coalesce+0x2aa/0x890 [bcache]
> ? bch_extent_bad+0x70/0x170 [bcache]
> btree_gc_recurse+0x130/0x390 [bcache]
> ? btree_gc_mark_node+0x72/0x230 [bcache]
> bch_btree_gc+0x5da/0x600 [bcache]
> ? cpuusage_read+0x10/0x10
> ? bch_btree_gc+0x600/0x600 [bcache]
> bch_gc_thread+0x135/0x180 [bcache]
>
> [...]

Applied, thanks!

[1/1] bcache: revert replacing IS_ERR_OR_NULL with IS_ERR
(no commit info)

Best regards,
--
Jens Axboe