WARNING in reconnect_path

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 9f31eb60 Linux 4.19.53
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15e6e709a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=7a36b9832db62b25
dashboard link: https://syzkaller.appspot.com/bug?extid=773a05d367d17401cb54
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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+773a05...@syzkaller.appspotmail.com

RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f44a861a6d4
R13: 00000000004c5828 R14: 00000000004d9e48 R15: 0000000000000003
WARNING: CPU: 0 PID: 23578 at fs/exportfs/expfs.c:96 clear_disconnected
fs/exportfs/expfs.c:96 [inline]
WARNING: CPU: 0 PID: 23578 at fs/exportfs/expfs.c:96
reconnect_path+0x524/0x6c0 fs/exportfs/expfs.c:232
Kernel panic - not syncing: panic_on_warn set ...

kobject: 'kvm' (00000000df1ad2b2): kobject_uevent_env
CPU: 0 PID: 23578 Comm: syz-executor.2 Not tainted 4.19.53+ #25
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+0x263/0x507 kernel/panic.c:185
kobject: 'kvm' (00000000df1ad2b2): fill_kobj_path: path
= '/devices/virtual/misc/kvm'
kobject: 'loop0' (0000000080ed97b5): kobject_uevent_env
__warn.cold+0x20/0x4a kernel/panic.c:540
kobject: 'loop0' (0000000080ed97b5): fill_kobj_path: path
= '/devices/virtual/block/loop0'
report_bug+0x263/0x2b0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
fixup_bug arch/x86/kernel/traps.c:173 [inline]
do_error_trap+0x204/0x360 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1013
RIP: 0010:clear_disconnected fs/exportfs/expfs.c:96 [inline]
RIP: 0010:reconnect_path+0x524/0x6c0 fs/exportfs/expfs.c:232
Code: 72 90 8d ff 48 8b 5d c8 e9 24 fc ff ff e8 b4 15 48 ff 48 8b 7d c8 e8
5b 90 8d ff e8 a6 15 48 ff e9 21 fe ff ff e8 9c 15 48 ff <0f> 0b e9 b4 fe
ff ff e8 90 15 48 ff 48 8b 55 c0 48 b8 00 00 00 00
RSP: 0018:ffff8880a55dfbd8 EFLAGS: 00010246
RAX: 0000000000040000 RBX: 0000000000000020 RCX: ffffc9000a2a1000
RDX: 0000000000040000 RSI: ffffffff82230114 RDI: ffff8880948ee300
RBP: ffff8880a55dfc28 R08: ffff888080a56100 R09: 0000000000000000
R10: ffffed1015d04732 R11: ffff8880ae823993 R12: ffff8880948ee2c0
R13: dffffc0000000000 R14: ffff8880948ee2c0 R15: ffff88809814fe20
exportfs_decode_fh+0x4a8/0x6ee fs/exportfs/expfs.c:457
do_handle_to_path fs/fhandle.c:152 [inline]
handle_to_path fs/fhandle.c:207 [inline]
do_handle_open+0x332/0x6e0 fs/fhandle.c:223
__do_sys_open_by_handle_at fs/fhandle.c:265 [inline]
__se_sys_open_by_handle_at fs/fhandle.c:256 [inline]
__x64_sys_open_by_handle_at+0x76/0xb0 fs/fhandle.c:256
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4592c9
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f44a8619c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000130
RAX: ffffffffffffffda RBX: 00007f44a8619c90 RCX: 00000000004592c9
RDX: 0000000000000000 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f44a861a6d4
R13: 00000000004c5828 R14: 00000000004d9e48 R15: 0000000000000003
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.