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Date: Tue, 26 Mar 2024 08:16:39 +1100
From: Dave Chinner <david@fromorbit.com>
To: syzbot <syzbot+fa52b47267f5cac8c654@syzkaller.appspotmail.com>
Cc: chandan.babu@oracle.com, djwong@kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-xfs@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [xfs?] possible deadlock in xfs_qm_dqget
Message-ID: <ZgHptxp5Bc4tf3Wc@dread.disaster.area>
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On Mon, Mar 25, 2024 at 01:35:33PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    fe46a7dd189e Merge tag 'sound-6.9-rc1' of git://git.kernel..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=102618b1180000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=fe78468a74fdc3b7
> dashboard link: https://syzkaller.appspot.com/bug?extid=fa52b47267f5cac8c654
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/0f7abe4afac7/disk-fe46a7dd.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/82598d09246c/vmlinux-fe46a7dd.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/efa23788c875/bzImage-fe46a7dd.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+fa52b47267f5cac8c654@syzkaller.appspotmail.com
> 
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.8.0-syzkaller-08951-gfe46a7dd189e #0 Not tainted
> ------------------------------------------------------
> syz-executor.5/6047 is trying to acquire lock:
> ffffffff8e21f720 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:303 [inline]
> ffffffff8e21f720 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3746 [inline]
> ffffffff8e21f720 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3827 [inline]
> ffffffff8e21f720 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc+0x48/0x340 mm/slub.c:3852
> 
> but task is already holding lock:
> ffff88801f58d958 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqget_cache_insert fs/xfs/xfs_dquot.c:825 [inline]
> ffff88801f58d958 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqget+0x2c4/0x640 fs/xfs/xfs_dquot.c:901
> 
> which lock already depends on the new lock.

#syz dup: possible deadlock in xfs_qm_dqget_cache_insert
-- 
Dave Chinner
david@fromorbit.com