Message-Id: <20220607160020.c088f4d29929310f2a3c1c32@linux-foundation.org>
Date:   Tue, 7 Jun 2022 16:00:20 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     syzbot <syzbot+2c93b863a7698df84bad@...kaller.appspotmail.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, syzkaller-bugs@...glegroups.com,
        willy@...radead.org,
        Stephen Brennan <stephen.s.brennan@...cle.com>,
        David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Konstantin Komarov <almaz.alexandrovich@...agon-software.com>,
        ntfs3@...ts.linux.dev
Subject: Re: [syzbot] WARNING: locking bug in truncate_inode_pages_final

Lots of cc's added.

On Tue, 07 Jun 2022 00:16:29 -0700 syzbot <syzbot+2c93b863a7698df84bad@...kaller.appspotmail.com> wrote:

> Hello,

Thanks.

> syzbot found the following issue on:

Oh dear.

> HEAD commit:    d1dc87763f40 assoc_array: Fix BUG_ON during garbage collect

I think this bisection is wrong.

I sure hope it's wrong - that patch went straight from the mailing list
into mainline and two days later was added to what appears to be every
-stable kernel we own.  It spent no time in -next except for a week or
so when I was sitting on an earlier version.

But I think the bisection is wrong.  I don't see how d1dc87763f40 can
affect ntfs3 and pagecache truncate.

Does that testcase even use the security keyrings code?  I'd be
suspicious of ntfs3 here.

> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14979947f00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c51cd24814bb5665
> dashboard link: https://syzkaller.appspot.com/bug?extid=2c93b863a7698df84bad
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> 
> Unfortunately, I don't have any reproducer for this issue yet.

Confused.  How is it possible to do a git-bisect without a reproducer?

> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+2c93b863a7698df84bad@...kaller.appspotmail.com
> 
> ntfs3: loop3: Different NTFS' sector size (2048) and media sector size (512)
> ntfs3: loop3: Different NTFS' sector size (2048) and media sector size (512)
> ------------[ cut here ]------------
> releasing a pinned lock
> WARNING: CPU: 2 PID: 21856 at kernel/locking/lockdep.c:5349 __lock_release kernel/locking/lockdep.c:5349 [inline]
> WARNING: CPU: 2 PID: 21856 at kernel/locking/lockdep.c:5349 lock_release+0x6a9/0x780 kernel/locking/lockdep.c:5685
> Modules linked in:
> CPU: 2 PID: 21856 Comm: syz-executor.3 Not tainted 5.18.0-syzkaller-11972-gd1dc87763f40 #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
> RIP: 0010:__lock_release kernel/locking/lockdep.c:5349 [inline]
> RIP: 0010:lock_release+0x6a9/0x780 kernel/locking/lockdep.c:5685
> Code: 68 00 e9 5a fa ff ff 4c 89 f7 e8 f2 3d 68 00 e9 36 fc ff ff e8 78 3d 68 00 e9 f5 fb ff ff 48 c7 c7 e0 9a cc 89 e8 d1 84 d3 07 <0f> 0b e9 87 fb ff ff e8 3b b3 18 08 48 c7 c7 4c 44 bb 8d e8 4f 3d
> RSP: 0018:ffffc90003497a00 EFLAGS: 00010082
> RAX: 0000000000000000 RBX: ffff88801e742c48 RCX: 0000000000000000
> RDX: 0000000000040000 RSI: ffffffff81601908 RDI: fffff52000692f32
> RBP: 1ffff92000692f42 R08: 0000000000000005 R09: 0000000000000000
> R10: 0000000080000001 R11: 0000000000000001 R12: ffff88804fb22498
> R13: 0000000000000002 R14: ffff88801e742c18 R15: ffff88801e7421c0
> FS:  00007f64be4cb700(0000) GS:ffff88802cc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f64be4cc000 CR3: 00000000669a7000 CR4: 0000000000150ee0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 000000000000003b DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:157 [inline]
>  _raw_spin_unlock_irq+0x12/0x40 kernel/locking/spinlock.c:202
>  spin_unlock_irq include/linux/spinlock.h:399 [inline]
>  truncate_inode_pages_final+0x5f/0x80 mm/truncate.c:484
>  ntfs_evict_inode+0x16/0xa0 fs/ntfs3/inode.c:1750
>  evict+0x2ed/0x6b0 fs/inode.c:664
>  iput_final fs/inode.c:1744 [inline]
>  iput.part.0+0x562/0x820 fs/inode.c:1770
>  iput+0x58/0x70 fs/inode.c:1760
>  ntfs_fill_super+0x2d66/0x3730 fs/ntfs3/super.c:1180
>  get_tree_bdev+0x440/0x760 fs/super.c:1292
>  vfs_get_tree+0x89/0x2f0 fs/super.c:1497
>  do_new_mount fs/namespace.c:3040 [inline]
>  path_mount+0x1320/0x1fa0 fs/namespace.c:3370
>  do_mount fs/namespace.c:3383 [inline]
>  __do_sys_mount fs/namespace.c:3591 [inline]
>  __se_sys_mount fs/namespace.c:3568 [inline]
>  __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x46/0xb0
> RIP: 0033:0x7f64bd28a63a
> Code: 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 b8 04 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f64be4caf88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 00007f64bd28a63a
> RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f64be4cafe0
> RBP: 00007f64be4cb020 R08: 00007f64be4cb020 R09: 0000000020000000
> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000020000000
> R13: 0000000020000100 R14: 00007f64be4cafe0 R15: 000000002007a980
>  </TASK>
> 
> 
> ---
> 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@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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