syzbot


possible deadlock in xfs_qm_dqget

Status: closed as dup on 2024/03/25 21:16
Subsystems: xfs
[Documentation on labels]
Reported-by: syzbot+fa52b47267f5cac8c654@syzkaller.appspotmail.com
First crash: 245d, last: 241d
Duplicate of
Title Repro Cause bisect Fix bisect Count Last Reported
possible deadlock in xfs_qm_dqget_cache_insert xfs 8 252d 253d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [xfs?] possible deadlock in xfs_qm_dqget 1 (2) 2024/03/25 21:16

Sample crash report:
XFS (loop3): Quotacheck: Done.
======================================================
WARNING: possible circular locking dependency detected
6.8.0-syzkaller-08951-gfe46a7dd189e #0 Not tainted
------------------------------------------------------
syz-executor.3/6472 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:
ffff88802bf04158 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqget_cache_insert fs/xfs/xfs_dquot.c:825 [inline]
ffff88802bf04158 (&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:

-> #2 (&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_dqget_cache_lookup+0x30/0x870 fs/xfs/xfs_dquot.c:784
       xfs_qm_dqget_inode+0x353/0xaa0 fs/xfs/xfs_dquot.c:986
       xfs_qm_dqattach_one+0x185/0x5e0 fs/xfs/xfs_qm.c:278
       xfs_qm_dqattach_locked+0x3fc/0x4e0 fs/xfs/xfs_qm.c:337
       xfs_qm_vop_dqalloc+0x3fd/0xef0 fs/xfs/xfs_qm.c:1710
       xfs_create+0x568/0x1300 fs/xfs/xfs_inode.c:1041
       xfs_generic_create+0x495/0xd70 fs/xfs/xfs_iops.c:199
       lookup_open fs/namei.c:3497 [inline]
       open_last_lookups fs/namei.c:3566 [inline]
       path_openat+0x1427/0x3240 fs/namei.c:3796
       do_filp_open+0x235/0x490 fs/namei.c:3826
       do_sys_openat2+0x13e/0x1d0 fs/open.c:1406
       do_sys_open fs/open.c:1421 [inline]
       __do_sys_openat fs/open.c:1437 [inline]
       __se_sys_openat fs/open.c:1432 [inline]
       __x64_sys_openat+0x247/0x2a0 fs/open.c:1432
       do_syscall_64+0xfd/0x240
       entry_SYSCALL_64_after_hwframe+0x6d/0x75

-> #1 (&xfs_dir_ilock_class){++++}-{3:3}:
       lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
       down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1695
       xfs_reclaim_inode fs/xfs/xfs_icache.c:945 [inline]
       xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1631 [inline]
       xfs_icwalk_ag+0x1216/0x1aa0 fs/xfs/xfs_icache.c:1713
       xfs_icwalk fs/xfs/xfs_icache.c:1762 [inline]
       xfs_reclaim_inodes_nr+0x257/0x360 fs/xfs/xfs_icache.c:1011
       super_cache_scan+0x411/0x4b0 fs/super.c:227
       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+0x913/0xef0 fs/xfs/xfs_qm.c:1773
       xfs_fileattr_set+0x3ff/0x1920 fs/xfs/xfs_ioctl.c:1347
       vfs_fileattr_set+0x901/0xd50 fs/ioctl.c:697
       ioctl_fssetxattr fs/ioctl.c:759 [inline]
       do_vfs_ioctl+0x1a9c/0x2e50 fs/ioctl.c:873
       __do_sys_ioctl fs/ioctl.c:902 [inline]
       __se_sys_ioctl+0x81/0x170 fs/ioctl.c:890
       do_syscall_64+0xfd/0x240
       entry_SYSCALL_64_after_hwframe+0x6d/0x75

other info that might help us debug this:

Chain exists of:
  fs_reclaim --> &xfs_dir_ilock_class --> &qinf->qi_tree_lock

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz-executor.3/6472:
 #0: ffff888060da6420 (sb_writers#16){.+.+}-{0:0}, at: mnt_want_write_file+0x61/0x200 fs/namespace.c:453
 #1: ffff888149c42238 (&inode->i_sb->s_type->i_mutex_dir_key){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:793 [inline]
 #1: ffff888149c42238 (&inode->i_sb->s_type->i_mutex_dir_key){+.+.}-{3:3}, at: vfs_fileattr_set+0x139/0xd50 fs/ioctl.c:682
 #2: ffff88802bf04158 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqget_cache_insert fs/xfs/xfs_dquot.c:825 [inline]
 #2: ffff88802bf04158 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqget+0x2c4/0x640 fs/xfs/xfs_dquot.c:901

stack backtrace:
CPU: 1 PID: 6472 Comm: syz-executor.3 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+0x913/0xef0 fs/xfs/xfs_qm.c:1773
 xfs_fileattr_set+0x3ff/0x1920 fs/xfs/xfs_ioctl.c:1347
 vfs_fileattr_set+0x901/0xd50 fs/ioctl.c:697
 ioctl_fssetxattr fs/ioctl.c:759 [inline]
 do_vfs_ioctl+0x1a9c/0x2e50 fs/ioctl.c:873
 __do_sys_ioctl fs/ioctl.c:902 [inline]
 __se_sys_ioctl+0x81/0x170 fs/ioctl.c:890
 do_syscall_64+0xfd/0x240
 entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7f748407dda9
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:00007f7484e280c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f74841abf80 RCX: 00007f748407dda9
RDX: 0000000020000000 RSI: 00000000401c5820 RDI: 0000000000000004
RBP: 00007f74840ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f74841abf80 R15: 00007ffc95a58798
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/03/26 00:59 upstream fe46a7dd189e 0ea90952 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in xfs_qm_dqget
2024/03/25 16:19 upstream fe46a7dd189e 0ea90952 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in xfs_qm_dqget
2024/03/21 20:29 upstream fe46a7dd189e 6753db5c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in xfs_qm_dqget
* Struck through repros no longer work on HEAD.