WARNING in __blkdev_put

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 091a1eaa0e30 Merge branch 'akpm'
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=119edc5e400000
kernel config: https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb
dashboard link: https://syzkaller.appspot.com/bug?extid=e79f1fbe5c613b34332b
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org
vi...@zeniv.linux.org.uk]

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+e79f1f...@syzkaller.appspotmail.com

loop0: p1
loop1: p1
loop_reread_partitions: partition scan of loop3 () failed (rc=-16)
Unknown ioctl 19276
WARNING: CPU: 0 PID: 23611 at fs/block_dev.c:1788 __blkdev_put+0x688/0x830
fs/block_dev.c:1788
kobject: 'loop2' (000000005de1cfdf): kobject_uevent_env
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 23611 Comm: syz-executor1 Not tainted 4.19.0-rc6+ #270
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+0x1c4/0x2b4 lib/dump_stack.c:113
kobject: 'loop2' (000000005de1cfdf): fill_kobj_path: path
= '/devices/virtual/block/loop2'
panic+0x238/0x4e7 kernel/panic.c:184
__warn.cold.8+0x163/0x1ba kernel/panic.c:536
report_bug+0x254/0x2d0 lib/bug.c:186
kobject: 'loop5' (000000002c42f3e9): kobject_uevent_env
fixup_bug arch/x86/kernel/traps.c:178 [inline]
do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
kobject: 'loop5' (000000002c42f3e9): fill_kobj_path: path
= '/devices/virtual/block/loop5'
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:993
RIP: 0010:__blkdev_put+0x688/0x830 fs/block_dev.c:1788
Code: ff ff ff ba 01 00 00 00 4c 89 e7 e8 92 f9 ff ff e9 79 fd ff ff 48 c7
85 50 ff ff ff 08 00 00 00 e9 7f fb ff ff e8 28 63 9e ff <0f> 0b e9 0e fb
ff ff e8 1c 63 9e ff 48 8b bd 48 ff ff ff 48 c7 83
RSP: 0018:ffff880186a1fa38 EFLAGS: 00010216
RAX: 0000000000040000 RBX: ffff8801d4bb9380 RCX: ffffc90003e6e000
RDX: 000000000001407c RSI: ffffffff81e07268 RDI: 0000000000000005
kobject: 'loop1' (00000000d5a9ae3e): kobject_uevent_env
RBP: ffff880186a1fb30 R08: ffff880129c66200 R09: ffffed003a977273
R10: ffff880186a1fa28 R11: ffff8801d4bb939f R12: ffff8801d4bb9384
R13: 0000000000000001 R14: ffff8801d239b640 R15: ffffffff81e07950
kobject: 'loop1' (00000000d5a9ae3e): fill_kobj_path: path
= '/devices/virtual/block/loop1'
blkdev_put+0x98/0x540 fs/block_dev.c:1858
blkdev_close+0x8b/0xb0 fs/block_dev.c:1865
__fput+0x385/0xa30 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x411051
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 19 00 00 c3 48
83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48
89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fa675d8ca10 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007fa675d8d6d4 RCX: 0000000000411051
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000000 R09: 000000000000000c
R10: 0000000000000064 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000004 R14: 0000000000000005 R15: 0000000000000001
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.