WARNING in destroy_workqueue (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 0939221e Merge tag 'fixes_for_v5.1-rc2' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11208a3b200000
kernel config: https://syzkaller.appspot.com/x/.config?x=9a31fb246de2a622
dashboard link: https://syzkaller.appspot.com/bug?extid=f9bd73d4caca60549c6b
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [darric...@oracle.com linux-...@vger.kernel.org
linu...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f9bd73...@syzkaller.appspotmail.com

XFS (loop5): Invalid superblock magic number
WARNING: CPU: 0 PID: 4665 at kernel/workqueue.c:4334
destroy_workqueue+0x1ab/0x700 kernel/workqueue.c:4334
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 4665 Comm: syz-executor.5 Not tainted 5.1.0-rc1+ #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
panic+0x2cb/0x65c kernel/panic.c:214
__warn.cold+0x20/0x45 kernel/panic.c:571
report_bug+0x263/0x2b0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:179 [inline]
fixup_bug arch/x86/kernel/traps.c:174 [inline]
do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973
RIP: 0010:destroy_workqueue+0x1ab/0x700 kernel/workqueue.c:4334
Code: 08 3c 03 0f 8e fe 04 00 00 48 8b 45 d0 bf 01 00 00 00 8b 58 18 89 de
e8 a3 61 25 00 83 fb 01 0f 8e 8e 00 00 00 e8 15 60 25 00 <0f> 0b e8 0e 60
25 00 48 8b 7d c8 e8 95 4b c3 05 e8 80 f7 ff ff e9
RSP: 0018:ffff88805bb6fbb0 EFLAGS: 00010246
RAX: 0000000000040000 RBX: 0000000000000002 RCX: ffffc90010884000
RDX: 0000000000040000 RSI: ffffffff814b0f7b RDI: 0000000000000005
RBP: ffff88805bb6fbf8 R08: ffff888056f02640 R09: ffffed1015d05bc8
R10: ffffed1015d05bc7 R11: ffff8880ae82de3b R12: 000000000000000f
R13: dffffc0000000000 R14: ffff88805d87e840 R15: 0000000000000000
xfs_destroy_mount_workqueues+0x171/0x1c0 fs/xfs/xfs_super.c:908
xfs_fs_fill_super+0x8e9/0x1670 fs/xfs/xfs_super.c:1786
mount_bdev+0x307/0x3c0 fs/super.c:1346
xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1834
legacy_get_tree+0xf2/0x200 fs/fs_context.c:584
vfs_get_tree+0x123/0x450 fs/super.c:1481
do_new_mount fs/namespace.c:2622 [inline]
do_mount+0x1436/0x2c40 fs/namespace.c:2942
ksys_mount+0xdb/0x150 fs/namespace.c:3151
__do_sys_mount fs/namespace.c:3165 [inline]
__se_sys_mount fs/namespace.c:3162 [inline]
__x64_sys_mount+0xbe/0x150 fs/namespace.c:3162
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45ac7a
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 2d 8e fb ff c3 66 2e 0f
1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff
ff 0f 83 0a 8e fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f5dbd9aaa88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f5dbd9aab40 RCX: 000000000045ac7a
RDX: 00007f5dbd9aaae0 RSI: 00000000200000c0 RDI: 00007f5dbd9aab00
RBP: 0000000000000000 R08: 00007f5dbd9aab40 R09: 00007f5dbd9aaae0
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000004
R13: 00000000004c6b80 R14: 00000000004dc190 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.