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Date: Tue, 19 Mar 2024 13:19:23 -0400
From: Stefan Hajnoczi <stefanha@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: syzbot <syzbot+70f57d8a3ae84934c003@syzkaller.appspotmail.com>,
	jasowang@redhat.com, linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com, virtualization@lists.linux.dev,
	xuanzhuo@linux.alibaba.com, Paolo Bonzini <pbonzini@redhat.com>,
	Mike Christie <michael.christie@oracle.com>
Subject: Re: [syzbot] [virtualization?] upstream boot error: WARNING:
 refcount bug in __free_pages_ok
Message-ID: <20240319171923.GA1123315@fedora>
References: <000000000000cfd4800613fe79b1@google.com>
 <20240319033941-mutt-send-email-mst@kernel.org>
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On Tue, Mar 19, 2024 at 03:40:53AM -0400, Michael S. Tsirkin wrote:
> On Tue, Mar 19, 2024 at 12:32:26AM -0700, syzbot wrote:
> > Hello,
> >=20
> > syzbot found the following issue on:
> >=20
> > HEAD commit:    b3603fcb79b1 Merge tag 'dlm-6.9' of git://git.kernel.or=
g/p..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=3D10f04c81180=
000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=3Dfcb5bfbee0a=
42b54
> > dashboard link: https://syzkaller.appspot.com/bug?extid=3D70f57d8a3ae84=
934c003
> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for D=
ebian) 2.40
> >=20
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/43969dffd4a6/d=
isk-b3603fcb.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/ef48ab3b378b/vmli=
nux-b3603fcb.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/728f5ff2b6fe=
/bzImage-b3603fcb.xz
> >=20
> > IMPORTANT: if you fix the issue, please add the following tag to the co=
mmit:
> > Reported-by: syzbot+70f57d8a3ae84934c003@syzkaller.appspotmail.com
> >=20
> > Key type pkcs7_test registered
> > Block layer SCSI generic (bsg) driver version 0.4 loaded (major 239)
> > io scheduler mq-deadline registered
> > io scheduler kyber registered
> > io scheduler bfq registered
> > input: Power Button as /devices/LNXSYSTM:00/LNXPWRBN:00/input/input0
> > ACPI: button: Power Button [PWRF]
> > input: Sleep Button as /devices/LNXSYSTM:00/LNXSLPBN:00/input/input1
> > ACPI: button: Sleep Button [SLPF]
> > ioatdma: Intel(R) QuickData Technology Driver 5.00
> > ACPI: \_SB_.LNKC: Enabled at IRQ 11
> > virtio-pci 0000:00:03.0: virtio_pci: leaving for legacy driver
> > ACPI: \_SB_.LNKD: Enabled at IRQ 10
> > virtio-pci 0000:00:04.0: virtio_pci: leaving for legacy driver
> > ACPI: \_SB_.LNKB: Enabled at IRQ 10
> > virtio-pci 0000:00:06.0: virtio_pci: leaving for legacy driver
> > virtio-pci 0000:00:07.0: virtio_pci: leaving for legacy driver
> > N_HDLC line discipline registered with maxframe=3D4096
> > Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> > 00:03: ttyS0 at I/O 0x3f8 (irq =3D 4, base_baud =3D 115200) is a 16550A
> > 00:04: ttyS1 at I/O 0x2f8 (irq =3D 3, base_baud =3D 115200) is a 16550A
> > 00:05: ttyS2 at I/O 0x3e8 (irq =3D 6, base_baud =3D 115200) is a 16550A
> > 00:06: ttyS3 at I/O 0x2e8 (irq =3D 7, base_baud =3D 115200) is a 16550A
> > Non-volatile memory driver v1.3
> > Linux agpgart interface v0.103
> > ACPI: bus type drm_connector registered
> > [drm] Initialized vgem 1.0.0 20120112 for vgem on minor 0
> > [drm] Initialized vkms 1.0.0 20180514 for vkms on minor 1
> > Console: switching to colour frame buffer device 128x48
> > platform vkms: [drm] fb0: vkmsdrmfb frame buffer device
> > usbcore: registered new interface driver udl
> > brd: module loaded
> > loop: module loaded
> > zram: Added device: zram0
> > null_blk: disk nullb0 created
> > null_blk: module loaded
> > Guest personality initialized and is inactive
> > VMCI host device registered (name=3Dvmci, major=3D10, minor=3D118)
> > Initialized host personality
> > usbcore: registered new interface driver rtsx_usb
> > usbcore: registered new interface driver viperboard
> > usbcore: registered new interface driver dln2
> > usbcore: registered new interface driver pn533_usb
> > nfcsim 0.2 initialized
> > usbcore: registered new interface driver port100
> > usbcore: registered new interface driver nfcmrvl
> > Loading iSCSI transport class v2.0-870.
> > virtio_scsi virtio0: 1/0/0 default/read/poll queues
> > ------------[ cut here ]------------
> > refcount_t: decrement hit 0; leaking memory.
> > WARNING: CPU: 0 PID: 1 at lib/refcount.c:31 refcount_warn_saturate+0xfa=
/0x1d0 lib/refcount.c:31
> > Modules linked in:
> > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.8.0-syzkaller-11567-gb3603f=
cb79b1 #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS=
 Google 02/29/2024
> > RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
> > Code: b2 00 00 00 e8 57 d4 f2 fc 5b 5d c3 cc cc cc cc e8 4b d4 f2 fc c6=
 05 0c f9 ef 0a 01 90 48 c7 c7 a0 5d 1e 8c e8 b7 75 b5 fc 90 <0f> 0b 90 90 =
eb d9 e8 2b d4 f2 fc c6 05 e9 f8 ef 0a 01 90 48 c7 c7
> > RSP: 0000:ffffc90000066e18 EFLAGS: 00010246
> > RAX: 76f86e452fcad900 RBX: ffff8880210d2aec RCX: ffff888016ac8000
> > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> > RBP: 0000000000000004 R08: ffffffff8157ffe2 R09: fffffbfff1c396e0
> > R10: dffffc0000000000 R11: fffffbfff1c396e0 R12: ffffea000502cdc0
> > R13: ffffea000502cdc8 R14: 1ffffd4000a059b9 R15: 0000000000000000
> > FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:00000000000=
00000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: ffff88823ffff000 CR3: 000000000e132000 CR4: 00000000003506f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  <TASK>
> >  reset_page_owner include/linux/page_owner.h:25 [inline]
> >  free_pages_prepare mm/page_alloc.c:1141 [inline]
> >  __free_pages_ok+0xc54/0xd80 mm/page_alloc.c:1270
> >  make_alloc_exact+0xa3/0xf0 mm/page_alloc.c:4829
> >  vring_alloc_queue drivers/virtio/virtio_ring.c:319 [inline]
> >  vring_alloc_queue_split+0x20a/0x600 drivers/virtio/virtio_ring.c:1108
> >  vring_create_virtqueue_split+0xc6/0x310 drivers/virtio/virtio_ring.c:1=
158
> >  vring_create_virtqueue+0xca/0x110 drivers/virtio/virtio_ring.c:2683
> >  setup_vq+0xe9/0x2d0 drivers/virtio/virtio_pci_legacy.c:131
> >  vp_setup_vq+0xbf/0x330 drivers/virtio/virtio_pci_common.c:189
> >  vp_find_vqs_msix+0x8b2/0xc80 drivers/virtio/virtio_pci_common.c:331
> >  vp_find_vqs+0x4c/0x4e0 drivers/virtio/virtio_pci_common.c:408
> >  virtio_find_vqs include/linux/virtio_config.h:233 [inline]
> >  virtscsi_init+0x8db/0xd00 drivers/scsi/virtio_scsi.c:887
> >  virtscsi_probe+0x3ea/0xf60 drivers/scsi/virtio_scsi.c:945
> >  virtio_dev_probe+0x991/0xaf0 drivers/virtio/virtio.c:311
> >  really_probe+0x29e/0xc50 drivers/base/dd.c:658
> >  __driver_probe_device+0x1a2/0x3e0 drivers/base/dd.c:800
> >  driver_probe_device+0x50/0x430 drivers/base/dd.c:830
> >  __driver_attach+0x45f/0x710 drivers/base/dd.c:1216
> >  bus_for_each_dev+0x239/0x2b0 drivers/base/bus.c:368
> >  bus_add_driver+0x347/0x620 drivers/base/bus.c:673
> >  driver_register+0x23a/0x320 drivers/base/driver.c:246
> >  virtio_scsi_init+0x65/0xe0 drivers/scsi/virtio_scsi.c:1083
> >  do_one_initcall+0x248/0x880 init/main.c:1238
> >  do_initcall_level+0x157/0x210 init/main.c:1300
> >  do_initcalls+0x3f/0x80 init/main.c:1316
> >  kernel_init_freeable+0x435/0x5d0 init/main.c:1548
> >  kernel_init+0x1d/0x2b0 init/main.c:1437
> >  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
> >  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
> >  </TASK>
> >=20
>=20
> I think I saw this already and also with virtio scsi. virtio
> core does not seem to be doing anything special here,
> Cc virtio scsi maintainers.

The oldest commit that syzkaller found is a memory management pull
request:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?id=
=3De5eb28f6d1afebed4bb7d740a797d0390bd3a357

I can't reproduce the issue locally with QEMU 8.2.0 so I don't have a
way to bisect.

I reviewed the virtio_scsi.c git log and there have been few changes
over the last several months. I couldn't spot an issue in this patch,
but the most likely virtio-scsi commit is:

  commit 95e7249691f082a5178d4d6f60fcdee91da458ab
  Author: Mike Christie <michael.christie@oracle.com>
  Date:   Wed Dec 13 23:26:49 2023 -0600

      scsi: virtio_scsi: Add mq_poll support

Stefan

>=20
>=20
> > ---
> > This report is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@googlegroups.com.
> >=20
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> >=20
> > If the report is already addressed, let syzbot know by replying with:
> > #syz fix: exact-commit-title
> >=20
> > If you want to overwrite report's subsystems, reply with:
> > #syz set subsystems: new-subsystem
> > (See the list of subsystem names on the web dashboard)
> >=20
> > If the report is a duplicate of another one, reply with:
> > #syz dup: exact-subject-of-another-report
> >=20
> > If you want to undo deduplication, reply with:
> > #syz undup
>=20

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