Hi Zhiguo,
I got the below dmesg and the first bad commit is
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
commit 2c575026fae6e63771bd2a4c1d407214a8096a89
Author: Hong Zhiguo <[email protected]>
AuthorDate: Wed Nov 20 10:35:05 2013 -0700
Commit: Jens Axboe <[email protected]>
CommitDate: Wed Nov 20 15:33:04 2013 -0700
Update of blkg_stat and blkg_rwstat may happen in bh context.
While u64_stats_fetch_retry is only preempt_disable on 32bit
UP system. This is not enough to avoid preemption by bh and
may read strange 64 bit value.
Signed-off-by: Hong Zhiguo <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Cc: [email protected]
Signed-off-by: Jens Axboe <[email protected]>
+-----------------------------------------------------------+------------+------------+
| | 82023bb7f7 | 2c575026fa |
+-----------------------------------------------------------+------------+------------+
| boot_successes | 47 | 0 |
| boot_failures | 13 | 20 |
| BUG:kernel_boot_hang | 13 | 5 |
| inconsistent_IN-SOFTIRQ-W-SOFTIRQ-ON-W_usage | 0 | 15 |
| backtrace:smpboot_thread_fn | 0 | 15 |
| backtrace:vfs_read | 0 | 9 |
| backtrace:SyS_read | 0 | 9 |
| WARNING:CPU:PID:at_kernel/softirq.c:_local_bh_enable_ip() | 0 | 7 |
| BUG:spinlock_lockup_suspected_on_CPU | 0 | 1 |
| backtrace:do_mount | 0 | 6 |
| backtrace:SyS_mount | 0 | 6 |
| backtrace:async_run_entry_fn | 0 | 0 |
+-----------------------------------------------------------+------------+------------+
[ 12.318816] WARNING: CPU: 0 PID: 300 at kernel/softirq.c:156 _local_bh_enable_ip+0x34/0x97()
[ 12.320012] CPU: 0 PID: 300 Comm: mount Not tainted 3.12.0-10878-g2c57502 #1
[ 12.320012] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 12.320012] 00000000 00000000 d0017b58 c0a2b528 d0017b70 c025daed c026085e c04efc4a
[ 12.320012] d1ff5044 d0017bdc d0017b80 c025db8a 00000009 00000000 d0017b8c c026085e
[ 12.320012] d0017bbc d0017b94 c02608cc d0017ba8 c04efc4a d1061140 d1ff4e10 d10242b0
[ 12.320012] Call Trace:
[ 12.320012] [<c0a2b528>] dump_stack+0x16/0x18
[ 12.320012] [<c025daed>] warn_slowpath_common+0x50/0x67
[ 12.320012] [<c026085e>] ? _local_bh_enable_ip+0x34/0x97
[ 12.320012] [<c04efc4a>] ? blkg_rwstat_read+0x1d/0x24
[ 12.320012] [<c025db8a>] warn_slowpath_null+0xf/0x13
[ 12.320012] [<c026085e>] _local_bh_enable_ip+0x34/0x97
[ 12.320012] [<c02608cc>] local_bh_enable+0xb/0xd
[ 12.320012] [<c04efc4a>] blkg_rwstat_read+0x1d/0x24
[ 12.320012] [<c04f0f2c>] __cfq_set_active_queue+0x6b/0x188
[ 12.320012] [<c04f0760>] ? cfq_resort_rr_list+0x1f/0x23
[ 12.320012] [<c04ef459>] ? __arch_hweight32+0x8/0xa
[ 12.320012] [<c04f126f>] ? cfq_update_idle_window.isra.80+0x7d/0xe4
[ 12.320012] [<c024c11f>] ? kvm_clock_read+0x14/0x1d
[ 12.320012] [<c02329bc>] ? paravirt_sched_clock+0x9/0xd
[ 12.320012] [<c0232e67>] ? sched_clock+0x9/0xc
[ 12.320012] [<c0279714>] ? sched_clock_local.constprop.3+0xe/0x106
[ 12.320012] [<c04f367e>] cfq_dispatch_requests+0x528/0x7a8
[ 12.320012] [<c02329bc>] ? paravirt_sched_clock+0x9/0xd
[ 12.320012] [<c0232e67>] ? sched_clock+0x9/0xc
[ 12.320012] [<c04f26b0>] ? cfq_insert_request+0x18d/0x323
[ 12.320012] [<c0279902>] ? sched_clock_cpu+0xb8/0xc6
[ 12.320012] [<c02819f8>] ? trace_hardirqs_on+0xb/0xd
[ 12.320012] [<c0a34a8f>] ? _raw_spin_unlock_irq+0x27/0x30
[ 12.320012] [<c0281a9a>] ? trace_hardirqs_off+0xb/0xd
[ 12.320012] [<c04e0738>] blk_peek_request+0x57/0x180
[ 12.320012] [<c06007cf>] scsi_request_fn+0x38/0x42f
[ 12.320012] [<c04df0fc>] __blk_run_queue_uncond+0x21/0x2a
[ 12.320012] [<c04df118>] __blk_run_queue+0x13/0x15
[ 12.320012] [<c04e0ef9>] blk_queue_bio+0x1c7/0x1da
[ 12.320012] [<c04dfbf8>] generic_make_request+0x7f/0xb4
[ 12.320012] [<c04dfd02>] submit_bio+0xd5/0x107
[ 12.320012] [<c02f9872>] ? bio_alloc_bioset+0xb7/0x139
[ 12.320012] [<c02f782b>] _submit_bh+0x139/0x154
[ 12.320012] [<c02f7850>] submit_bh+0xa/0xc
[ 12.320012] [<c02f914c>] __bread+0x3e/0x59
[ 12.320012] [<c036ee6e>] ext4_fill_super+0x1c0/0x24d2
[ 12.320012] [<c04faec8>] ? string.isra.4+0x2d/0x92
[ 12.320012] [<c04ea741>] ? disk_name+0x20/0x65
[ 12.320012] [<c036ecae>] ? ext4_calculate_overhead+0x2df/0x2df
[ 12.320012] [<c02d96c8>] mount_bdev+0x12a/0x183
[ 12.320012] [<c036ecae>] ? ext4_calculate_overhead+0x2df/0x2df
[ 12.320012] [<c02d1013>] ? __kmalloc_track_caller+0x81/0xe2
[ 12.320012] [<c02ebd9d>] ? alloc_vfsmnt+0xe9/0x10f
[ 12.320012] [<c036b2e8>] ext4_mount+0x10/0x12
[ 12.320012] [<c036ecae>] ? ext4_calculate_overhead+0x2df/0x2df
[ 12.320012] [<c02d986b>] mount_fs+0xe/0x96
[ 12.320012] [<c02ec833>] vfs_kern_mount+0x40/0x9e
[ 12.320012] [<c02edc57>] do_mount+0x611/0x6f6
[ 12.320012] [<c02b900c>] ? strndup_user+0x2c/0x3d
[ 12.320012] [<c02edef4>] SyS_mount+0x71/0xa0
[ 12.320012] [<c0a35377>] syscall_call+0x7/0xb
[ 12.320012] ---[ end trace 1790dec9013df875 ]---
[ 12.320012]
[ 12.320012] =================================
[ 12.320012] [ INFO: inconsistent lock state ]
[ 12.320012] 3.12.0-10878-g2c57502 #1 Tainted: G W
[ 12.320012] ---------------------------------
[ 12.320012] inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
[ 12.320012] mount/300 [HC0[0]:SC0[0]:HE1:SE1] takes:
[ 12.320012] (&(&q->__queue_lock)->rlock){+.?...}, at: [<c04e0ed8>] blk_queue_bio+0x1a6/0x1da
[ 12.320012] {IN-SOFTIRQ-W} state was registered at:
[ 12.320012] [<c0282acb>] __lock_acquire+0x27d/0xbfe
[ 12.320012] [<c02836d0>] lock_acquire+0x56/0x72
[ 12.320012] [<c0a348ae>] _raw_spin_lock+0x24/0x54
[ 12.320012] [<c06010b3>] scsi_device_unbusy+0x5b/0x7e
[ 12.320012] [<c05fc3ac>] scsi_finish_command+0x1d/0xc7
[ 12.320012] [<c0601294>] scsi_softirq_done+0xd6/0xde
[ 12.320012] [<c04e47ee>] blk_done_softirq+0x6e/0x77
[ 12.320012] [<c02606ac>] __do_softirq+0x94/0x16d
[ 12.320012] [<c02607a3>] run_ksoftirqd+0x1e/0x54
[ 12.320012] [<c0276b43>] smpboot_thread_fn+0x102/0x116
[ 12.320012] [<c0271c95>] kthread+0xa0/0xa5
[ 12.320012] [<c0a35a37>] ret_from_kernel_thread+0x1b/0x28
[ 12.320012] irq event stamp: 2146
[ 12.320012] hardirqs last enabled at (2143): [<c0a34a8a>] _raw_spin_unlock_irq+0x22/0x30
[ 12.320012] hardirqs last disabled at (2144): [<c0a34953>] _raw_spin_lock_irq+0x11/0x5e
[ 12.320012] softirqs last enabled at (2146): [<c04efc4a>] blkg_rwstat_read+0x1d/0x24
[ 12.320012] softirqs last disabled at (2145): [<c04efc3e>] blkg_rwstat_read+0x11/0x24
[ 12.320012]
[ 12.320012] other info that might help us debug this:
[ 12.320012] Possible unsafe locking scenario:
[ 12.320012]
[ 12.320012] CPU0
[ 12.320012] ----
[ 12.320012] lock(&(&q->__queue_lock)->rlock);
[ 12.320012] <Interrupt>
[ 12.320012] lock(&(&q->__queue_lock)->rlock);
[ 12.320012]
[ 12.320012] *** DEADLOCK ***
[ 12.320012]
[ 12.320012] 2 locks held by mount/300:
[ 12.320012] #0: (&type->s_umount_key#17/1){+.+.+.}, at: [<c02d8b1f>] sget+0x1e4/0x355
[ 12.320012] #1: (&(&q->__queue_lock)->rlock){+.?...}, at: [<c04e0ed8>] blk_queue_bio+0x1a6/0x1da
[ 12.320012]
[ 12.320012] stack backtrace:
[ 12.320012] CPU: 0 PID: 300 Comm: mount Tainted: G W 3.12.0-10878-g2c57502 #1
[ 12.320012] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 12.320012] 00000000 d00935c0 d0017af4 c0a2b528 d0017b20 c0a27d03 c0d35294 c0d35193
[ 12.320012] c0d3515b c0d3517a c0d35184 c0d36010 d0093a44 c0281162 00000010 d0017b48
[ 12.320012] c028172e 00000006 00000000 d00935c0 00000004 00000006 d0093a44 d00935c0
[ 12.320012] Call Trace:
[ 12.320012] [<c0a2b528>] dump_stack+0x16/0x18
[ 12.320012] [<c0a27d03>] print_usage_bug+0x180/0x18d
[ 12.320012] [<c0281162>] ? print_shortest_lock_dependencies+0x13c/0x13c
[ 12.320012] [<c028172e>] mark_lock+0xf7/0x1df
[ 12.320012] [<c0281871>] mark_held_locks+0x5b/0x72
[ 12.320012] [<c02608b9>] ? _local_bh_enable_ip+0x8f/0x97
[ 12.320012] [<c02819d3>] trace_hardirqs_on_caller+0x14b/0x165
[ 12.320012] [<c04efc4a>] ? blkg_rwstat_read+0x1d/0x24
[ 12.320012] [<c02819f8>] trace_hardirqs_on+0xb/0xd
[ 12.320012] [<c02608b9>] _local_bh_enable_ip+0x8f/0x97
[ 12.320012] [<c02608cc>] local_bh_enable+0xb/0xd
[ 12.320012] [<c04efc4a>] blkg_rwstat_read+0x1d/0x24
[ 12.320012] [<c04f0f2c>] __cfq_set_active_queue+0x6b/0x188
[ 12.320012] [<c04f0760>] ? cfq_resort_rr_list+0x1f/0x23
[ 12.320012] [<c04ef459>] ? __arch_hweight32+0x8/0xa
[ 12.320012] [<c04f126f>] ? cfq_update_idle_window.isra.80+0x7d/0xe4
[ 12.320012] [<c024c11f>] ? kvm_clock_read+0x14/0x1d
[ 12.320012] [<c02329bc>] ? paravirt_sched_clock+0x9/0xd
[ 12.320012] [<c0232e67>] ? sched_clock+0x9/0xc
[ 12.320012] [<c0279714>] ? sched_clock_local.constprop.3+0xe/0x106
[ 12.320012] [<c04f367e>] cfq_dispatch_requests+0x528/0x7a8
[ 12.320012] [<c02329bc>] ? paravirt_sched_clock+0x9/0xd
[ 12.320012] [<c0232e67>] ? sched_clock+0x9/0xc
[ 12.320012] [<c04f26b0>] ? cfq_insert_request+0x18d/0x323
[ 12.320012] [<c0279902>] ? sched_clock_cpu+0xb8/0xc6
[ 12.320012] [<c02819f8>] ? trace_hardirqs_on+0xb/0xd
[ 12.320012] [<c0a34a8f>] ? _raw_spin_unlock_irq+0x27/0x30
[ 12.320012] [<c0281a9a>] ? trace_hardirqs_off+0xb/0xd
[ 12.320012] [<c04e0738>] blk_peek_request+0x57/0x180
[ 12.320012] [<c06007cf>] scsi_request_fn+0x38/0x42f
[ 12.320012] [<c04df0fc>] __blk_run_queue_uncond+0x21/0x2a
[ 12.320012] [<c04df118>] __blk_run_queue+0x13/0x15
[ 12.320012] [<c04e0ef9>] blk_queue_bio+0x1c7/0x1da
[ 12.320012] [<c04dfbf8>] generic_make_request+0x7f/0xb4
[ 12.320012] [<c04dfd02>] submit_bio+0xd5/0x107
[ 12.320012] [<c02f9872>] ? bio_alloc_bioset+0xb7/0x139
[ 12.320012] [<c02f782b>] _submit_bh+0x139/0x154
[ 12.320012] [<c02f7850>] submit_bh+0xa/0xc
[ 12.320012] [<c02f914c>] __bread+0x3e/0x59
[ 12.320012] [<c036ee6e>] ext4_fill_super+0x1c0/0x24d2
[ 12.320012] [<c04faec8>] ? string.isra.4+0x2d/0x92
[ 12.320012] [<c04ea741>] ? disk_name+0x20/0x65
[ 12.320012] [<c036ecae>] ? ext4_calculate_overhead+0x2df/0x2df
[ 12.320012] [<c02d96c8>] mount_bdev+0x12a/0x183
[ 12.320012] [<c036ecae>] ? ext4_calculate_overhead+0x2df/0x2df
[ 12.320012] [<c02d1013>] ? __kmalloc_track_caller+0x81/0xe2
[ 12.320012] [<c02ebd9d>] ? alloc_vfsmnt+0xe9/0x10f
[ 12.320012] [<c036b2e8>] ext4_mount+0x10/0x12
[ 12.320012] [<c036ecae>] ? ext4_calculate_overhead+0x2df/0x2df
[ 12.320012] [<c02d986b>] mount_fs+0xe/0x96
[ 12.320012] [<c02ec833>] vfs_kern_mount+0x40/0x9e
[ 12.320012] [<c02edc57>] do_mount+0x611/0x6f6
[ 12.320012] [<c02b900c>] ? strndup_user+0x2c/0x3d
[ 12.320012] [<c02edef4>] SyS_mount+0x71/0xa0
[ 12.320012] [<c0a35377>] syscall_call+0x7/0xb
git bisect start v3.13 v3.12 --
git bisect good 3bad8bb5cd3048a67df43ac6b1e2f191f19d9ff0 # 15:26 20+ 9 Merge branch 'for-next' of git://git.samba.org/sfrench/cifs-2.6
git bisect bad 843f4f4bb1a2c4c196a1af1d18bb6477a580ac78 # 15:33 0- 12 Merge tag 'trace-fixes-3.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
git bisect good a45299e72737c528975546a0680cace5d7364d27 # 15:57 20+ 3 Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect good 09759d1e13e06c2f6346b1b3285fbde2c1e794c6 # 16:14 20+ 1 Merge tag 'sound-3.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
git bisect bad b52b342d31fecfeab0e2a256dfd84ea84954a8d3 # 16:20 0- 7 Merge branch 'stable' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile
git bisect good ef1e4e32d595d3e6c9a6d3d2956f087d5886c5e5 # 16:36 20+ 6 Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
git bisect good 29be6345bbaec8502a70c4e2204d5818b48c4e8f # 16:53 20+ 4 Merge tag 'nfs-for-3.13-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
git bisect bad 5ee540613db504a10e15fafaf4c08cac96aa1823 # 17:00 0- 6 Merge branch 'for-linus' of git://git.kernel.dk/linux-block
git bisect bad e345d767f6530ec9cb0aabab7ea248072a9c6975 # 17:08 0- 5 Merge branch 'stable/for-jens-3.13-take-two' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip into for-linus
git bisect bad c170bbb45febc03ac4d34ba2b8bb55e06104b7e7 # 17:12 0- 1 block: submit_bio_wait() conversions
git bisect bad 2c575026fae6e63771bd2a4c1d407214a8096a89 # 17:21 0- 12 Update of blkg_stat and blkg_rwstat may happen in bh context. While u64_stats_fetch_retry is only preempt_disable on 32bit UP system. This is not enough to avoid preemption by bh and may read strange 64 bit value.
# first bad commit: [2c575026fae6e63771bd2a4c1d407214a8096a89] Update of blkg_stat and blkg_rwstat may happen in bh context. While u64_stats_fetch_retry is only preempt_disable on 32bit UP system. This is not enough to avoid preemption by bh and may read strange 64 bit value.
git bisect good 82023bb7f75b0052f40d3e74169d191c3e4e6286 # 17:42 60+ 13 Merge tag 'pm+acpi-2-3.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
git bisect bad 36efbdff85370263b2262022687c19ac7e7fe83e # 17:42 0- 13 Add linux-next specific files for 20140417
git bisect bad ebfc45ee7004088d610cd399d2dee6d95f87199b # 17:50 0- 10 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
git bisect bad 36efbdff85370263b2262022687c19ac7e7fe83e # 17:50 0- 13 Add linux-next specific files for 20140417
This script may reproduce the error.
-----------------------------------------------------------------------------
#!/bin/bash
kernel=$1
initrd=yocto-minimal-i386.cgz
wget --no-clobber https://github.com/fengguang/reproduce-kernel-bug/blob/master/initrd/$initrd
kvm=(
qemu-system-x86_64 -cpu kvm64 -enable-kvm -kernel $kernel
-initrd $initrd
-smp 2
-m 256M
-net nic,vlan=0,macaddr=00:00:00:00:00:00,model=virtio
-net user,vlan=0
-net nic,vlan=1,model=e1000
-net user,vlan=1
-boot order=nc
-no-reboot
-watchdog i6300esb
-serial stdio
-display none
-monitor null
)
append=(
debug
sched_debug
apic=debug
ignore_loglevel
sysrq_always_enabled
panic=10
prompt_ramdisk=0
earlyprintk=ttyS0,115200
console=ttyS0,115200
console=tty0
vga=normal
root=/dev/ram0
rw
)
"${kvm[@]}" --append "${append[*]}"
-----------------------------------------------------------------------------
Attached dmesg for the parent commit, too, to help confirm whether it is a noise error.
Thanks,
Jet
On 2014-04-20 14:30, Jet Chen wrote:
> Hi Zhiguo,
>
> I got the below dmesg and the first bad commit is
>
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> commit 2c575026fae6e63771bd2a4c1d407214a8096a89
> Author: Hong Zhiguo <[email protected]>
> AuthorDate: Wed Nov 20 10:35:05 2013 -0700
> Commit: Jens Axboe <[email protected]>
> CommitDate: Wed Nov 20 15:33:04 2013 -0700
>
> Update of blkg_stat and blkg_rwstat may happen in bh context.
> While u64_stats_fetch_retry is only preempt_disable on 32bit
> UP system. This is not enough to avoid preemption by bh and
> may read strange 64 bit value.
> Signed-off-by: Hong Zhiguo <[email protected]>
> Acked-by: Tejun Heo <[email protected]>
> Cc: [email protected]
> Signed-off-by: Jens Axboe <[email protected]>
>
>
>
> +-----------------------------------------------------------+------------+------------+
> | | 82023bb7f7 | 2c575026fa |
> +-----------------------------------------------------------+------------+------------+
> | boot_successes | 47 | 0 |
> | boot_failures | 13 | 20 |
> | BUG:kernel_boot_hang | 13 | 5 |
> | inconsistent_IN-SOFTIRQ-W-SOFTIRQ-ON-W_usage | 0 | 15 |
> | backtrace:smpboot_thread_fn | 0 | 15 |
> | backtrace:vfs_read | 0 | 9 |
> | backtrace:SyS_read | 0 | 9 |
> | WARNING:CPU:PID:at_kernel/softirq.c:_local_bh_enable_ip() | 0 | 7 |
> | BUG:spinlock_lockup_suspected_on_CPU | 0 | 1 |
> | backtrace:do_mount | 0 | 6 |
> | backtrace:SyS_mount | 0 | 6 |
> | backtrace:async_run_entry_fn | 0 | 0 |
> +-----------------------------------------------------------+------------+------------+
>
> [ 12.318816] WARNING: CPU: 0 PID: 300 at kernel/softirq.c:156 _local_bh_enable_ip+0x34/0x97()
Does this still happen with 3.15-rc2?
--
Jens Axboe
Hi,
I think one fix is to use "_local_bh_enable()" instead of "local_bh_enable()"
in u64_stats_fetch_retry_bh(). There's no enabling of irq in
_local_bh_enable().
But I wonder why we do "WARN_ON_ONCE(!irqs_disabled()
)" in
_local_bh_enable()? What's the bad thing if someone call
_local_bh_enable() with irqs_diabled()?
Is below change acceptable?
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 490fcbb..f446763 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -142,9 +142,11 @@ EXPORT_SYMBOL(_local_bh_enable);
void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
{
+ unsigned long flags;
+
WARN_ON_ONCE(in_irq() || irqs_disabled());
#ifdef CONFIG_TRACE_IRQFLAGS
- local_irq_disable();
+ raw_local_irq_save(flags);
#endif
/*
* Are softirqs going to be turned on now:
@@ -167,7 +169,7 @@ void __local_bh_enable_ip(unsigned long ip,
unsigned int cnt)
preempt_count_dec();
#ifdef CONFIG_TRACE_IRQFLAGS
- local_irq_enable();
+ raw_local_irq_restore(flags);
#endif
preempt_check_resched();
}
Zhiguo
On Tue, Apr 22, 2014 at 9:06 AM, Jens Axboe <[email protected]> wrote:
> On 2014-04-20 14:30, Jet Chen wrote:
>>
>> Hi Zhiguo,
>>
>> I got the below dmesg and the first bad commit is
>>
>> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>> commit 2c575026fae6e63771bd2a4c1d407214a8096a89
>> Author: Hong Zhiguo <[email protected]>
>> AuthorDate: Wed Nov 20 10:35:05 2013 -0700
>> Commit: Jens Axboe <[email protected]>
>> CommitDate: Wed Nov 20 15:33:04 2013 -0700
>>
>> Update of blkg_stat and blkg_rwstat may happen in bh context.
>> While u64_stats_fetch_retry is only preempt_disable on 32bit
>> UP system. This is not enough to avoid preemption by bh and
>> may read strange 64 bit value.
>> Signed-off-by: Hong Zhiguo <[email protected]>
>> Acked-by: Tejun Heo <[email protected]>
>> Cc: [email protected]
>> Signed-off-by: Jens Axboe <[email protected]>
>>
>>
>>
>>
>> +-----------------------------------------------------------+------------+------------+
>> | | 82023bb7f7 |
>> 2c575026fa |
>>
>> +-----------------------------------------------------------+------------+------------+
>> | boot_successes | 47 |
>> 0 |
>> | boot_failures | 13 |
>> 20 |
>> | BUG:kernel_boot_hang | 13 |
>> 5 |
>> | inconsistent_IN-SOFTIRQ-W-SOFTIRQ-ON-W_usage | 0 |
>> 15 |
>> | backtrace:smpboot_thread_fn | 0 |
>> 15 |
>> | backtrace:vfs_read | 0 |
>> 9 |
>> | backtrace:SyS_read | 0 |
>> 9 |
>> | WARNING:CPU:PID:at_kernel/softirq.c:_local_bh_enable_ip() | 0 |
>> 7 |
>> | BUG:spinlock_lockup_suspected_on_CPU | 0 |
>> 1 |
>> | backtrace:do_mount | 0 |
>> 6 |
>> | backtrace:SyS_mount | 0 |
>> 6 |
>> | backtrace:async_run_entry_fn | 0 |
>> 0 |
>>
>> +-----------------------------------------------------------+------------+------------+
>>
>> [ 12.318816] WARNING: CPU: 0 PID: 300 at kernel/softirq.c:156
>> _local_bh_enable_ip+0x34/0x97()
>
>
> Does this still happen with 3.15-rc2?
>
> --
> Jens Axboe
>
> --
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--
best regards
Hong Zhiguo