Re: [syzbot] WARNING in mntput_no_expire (3)

[Al Viro <viro@zeniv.linux.org.uk>]

On Tue, May 17, 2022 at 03:49:07PM -0700, syzbot wrote:
> Hello,
> 
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> WARNING in mntput_no_expire

Obvious question: which filesystem it is?

>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f3b7a03bd2b
> Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
> RSP: 002b:00007ffe9eb268b0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
> RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f3b7a03bd2b
> RDX: 0000001b2ff20000 RSI: 0000000000000000 RDI: 0000000000000003
> RBP: 00007f3b7a19d960 R08: 0000000000000000 R09: 00007ffe9ebbf080
> R10: 00007ffe9ebbf090 R11: 0000000000000293 R12: 00000000000181f5
> R13: 00007ffe9eb269b0 R14: 00007ffe9eb269d0 R15: 0000000000000032
>  </TASK>
> 
> 
> Tested on:
> 
> commit:         feb9c5e1 Merge tag 'for_linus' of git://git.kernel.org..
> git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
> console output: https://syzkaller.appspot.com/x/log.txt?x=15ee4759f00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=79caa0035f59d385
> dashboard link: https://syzkaller.appspot.com/bug?extid=5b1e53987f858500ec00
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> patch:          https://syzkaller.appspot.com/x/patch.diff?x=1108ae3af00000
>