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Date: Mon, 25 Mar 2024 13:35:33 -0700
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Subject: [syzbot] [xfs?] possible deadlock in xfs_qm_dqget
From: syzbot <syzbot+fa52b47267f5cac8c654@syzkaller.appspotmail.com>
To: 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
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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.


the existing dependency chain (in reverse order) is:

-> #1 (&qinf->qi_tree_lock){+.+.}-{3:3}:
       lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       xfs_qm_dqfree_one+0x66/0x170 fs/xfs/xfs_qm.c:1654
       xfs_qm_shrink_scan+0x33f/0x400 fs/xfs/xfs_qm.c:531
       do_shrink_slab+0x6d2/0x1140 mm/shrinker.c:435
       shrink_slab+0x1092/0x14d0 mm/shrinker.c:662
       shrink_one+0x423/0x7f0 mm/vmscan.c:4767
       shrink_many mm/vmscan.c:4828 [inline]
       lru_gen_shrink_node mm/vmscan.c:4929 [inline]
       shrink_node+0x37b8/0x3e70 mm/vmscan.c:5888
       kswapd_shrink_node mm/vmscan.c:6696 [inline]
       balance_pgdat mm/vmscan.c:6886 [inline]
       kswapd+0x17d1/0x36e0 mm/vmscan.c:7146
       kthread+0x2f2/0x390 kernel/kthread.c:388
       ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

-> #0 (fs_reclaim){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
       __fs_reclaim_acquire mm/page_alloc.c:3692 [inline]
       fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3706
       might_alloc include/linux/sched/mm.h:303 [inline]
       slab_pre_alloc_hook mm/slub.c:3746 [inline]
       slab_alloc_node mm/slub.c:3827 [inline]
       kmem_cache_alloc+0x48/0x340 mm/slub.c:3852
       radix_tree_node_alloc+0x8b/0x3c0 lib/radix-tree.c:276
       radix_tree_extend+0x148/0x5c0 lib/radix-tree.c:425
       __radix_tree_create lib/radix-tree.c:613 [inline]
       radix_tree_insert+0x15c/0x680 lib/radix-tree.c:712
       xfs_qm_dqget_cache_insert fs/xfs/xfs_dquot.c:826 [inline]
       xfs_qm_dqget+0x2d4/0x640 fs/xfs/xfs_dquot.c:901
       xfs_qm_vop_dqalloc+0x5a3/0xef0 fs/xfs/xfs_qm.c:1730
       xfs_setattr_nonsize+0x410/0xea0 fs/xfs/xfs_iops.c:707
       xfs_vn_setattr+0x2d1/0x320 fs/xfs/xfs_iops.c:1027
       notify_change+0xb9f/0xe70 fs/attr.c:497
       chown_common+0x501/0x850 fs/open.c:790
       do_fchownat+0x16d/0x250 fs/open.c:821
       __do_sys_chown fs/open.c:841 [inline]
       __se_sys_chown fs/open.c:839 [inline]
       __x64_sys_chown+0x82/0x90 fs/open.c:839
       do_syscall_64+0xfd/0x240
       entry_SYSCALL_64_after_hwframe+0x6d/0x75

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&qinf->qi_tree_lock);
                               lock(fs_reclaim);
                               lock(&qinf->qi_tree_lock);
  lock(fs_reclaim);

 *** DEADLOCK ***

3 locks held by syz-executor.5/6047:
 #0: ffff888028a02420 (sb_writers#16){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:409
 #1: ffff8880b4d650b8 (&inode->i_sb->s_type->i_mutex_dir_key){++++}-{3:3}, at: inode_lock include/linux/fs.h:793 [inline]
 #1: ffff8880b4d650b8 (&inode->i_sb->s_type->i_mutex_dir_key){++++}-{3:3}, at: chown_common+0x3e1/0x850 fs/open.c:780
 #2: ffff88801f58d958 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqget_cache_insert fs/xfs/xfs_dquot.c:825 [inline]
 #2: ffff88801f58d958 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqget+0x2c4/0x640 fs/xfs/xfs_dquot.c:901

stack backtrace:
CPU: 0 PID: 6047 Comm: syz-executor.5 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
 __fs_reclaim_acquire mm/page_alloc.c:3692 [inline]
 fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3706
 might_alloc include/linux/sched/mm.h:303 [inline]
 slab_pre_alloc_hook mm/slub.c:3746 [inline]
 slab_alloc_node mm/slub.c:3827 [inline]
 kmem_cache_alloc+0x48/0x340 mm/slub.c:3852
 radix_tree_node_alloc+0x8b/0x3c0 lib/radix-tree.c:276
 radix_tree_extend+0x148/0x5c0 lib/radix-tree.c:425
 __radix_tree_create lib/radix-tree.c:613 [inline]
 radix_tree_insert+0x15c/0x680 lib/radix-tree.c:712
 xfs_qm_dqget_cache_insert fs/xfs/xfs_dquot.c:826 [inline]
 xfs_qm_dqget+0x2d4/0x640 fs/xfs/xfs_dquot.c:901
 xfs_qm_vop_dqalloc+0x5a3/0xef0 fs/xfs/xfs_qm.c:1730
 xfs_setattr_nonsize+0x410/0xea0 fs/xfs/xfs_iops.c:707
 xfs_vn_setattr+0x2d1/0x320 fs/xfs/xfs_iops.c:1027
 notify_change+0xb9f/0xe70 fs/attr.c:497
 chown_common+0x501/0x850 fs/open.c:790
 do_fchownat+0x16d/0x250 fs/open.c:821
 __do_sys_chown fs/open.c:841 [inline]
 __se_sys_chown fs/open.c:839 [inline]
 __x64_sys_chown+0x82/0x90 fs/open.c:839
 do_syscall_64+0xfd/0x240
 entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7fe9a027dda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe99f5ff0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000005c
RAX: ffffffffffffffda RBX: 00007fe9a03abf80 RCX: 00007fe9a027dda9
RDX: 0000000039323420 RSI: 000000000000ee00 RDI: 0000000020000140
RBP: 00007fe9a02ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fe9a03abf80 R15: 00007ffd68c11948
 </TASK>


---
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