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Message-ID: <69411a8c.a70a0220.33cd7b.0136.GAE@google.com>
Date: Tue, 16 Dec 2025 00:38:36 -0800
From: syzbot <syzbot+854bcfe4b16484489a66@...kaller.appspotmail.com>
To: clm@...com, dsterba@...e.com, josef@...icpanda.com,
linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
syzkaller-bugs@...glegroups.com
Subject: [syzbot] [btrfs?] possible deadlock in btrfs_commit_inode_delayed_inode
(2)
Hello,
syzbot found the following issue on:
HEAD commit: d358e5254674 Merge tag 'for-6.19/dm-changes' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1711661a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=de48dccdf203ea90
dashboard link: https://syzkaller.appspot.com/bug?extid=854bcfe4b16484489a66
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-d358e525.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3fa1d04c1a85/vmlinux-d358e525.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a9b253146e36/bzImage-d358e525.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+854bcfe4b16484489a66@...kaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kswapd0/78 is trying to acquire lock:
ffff888042458610 (sb_internal#2){.+.+}-{0:0}, at: btrfs_commit_inode_delayed_inode+0x117/0x2b0 fs/btrfs/delayed-inode.c:1279
but task is already holding lock:
ffffffff8e251780 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6973 [inline]
ffffffff8e251780 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x92a/0x2820 mm/vmscan.c:7352
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (fs_reclaim){+.+.}-{0:0}:
__fs_reclaim_acquire mm/page_alloc.c:4301 [inline]
fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4315
might_alloc include/linux/sched/mm.h:317 [inline]
slab_pre_alloc_hook mm/slub.c:4904 [inline]
slab_alloc_node mm/slub.c:5239 [inline]
__kmalloc_cache_noprof+0x40/0x700 mm/slub.c:5771
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
btrfs_sysfs_add_qgroups+0xcd/0x2b0 fs/btrfs/sysfs.c:2693
btrfs_quota_enable+0x25b/0x2900 fs/btrfs/qgroup.c:1002
btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3613
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:614 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:776
btrfs_quota_enable+0x29d/0x2900 fs/btrfs/qgroup.c:1031
btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3613
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (btrfs_trans_num_extwriters){++++}-{0:0}:
join_transaction+0x1a4/0xd60 fs/btrfs/transaction.c:323
start_transaction+0x6b7/0x15f0 fs/btrfs/transaction.c:707
btrfs_rebuild_free_space_tree+0xad/0x6c0 fs/btrfs/free-space-tree.c:1330
btrfs_start_pre_rw_mount+0x128f/0x1bf0 fs/btrfs/disk-io.c:3052
open_ctree+0x2b11/0x3d20 fs/btrfs/disk-io.c:3603
btrfs_fill_super fs/btrfs/super.c:983 [inline]
btrfs_get_tree_super fs/btrfs/super.c:1946 [inline]
btrfs_get_tree_subvol fs/btrfs/super.c:2089 [inline]
btrfs_get_tree+0x1061/0x1920 fs/btrfs/super.c:2123
vfs_get_tree+0x92/0x2a0 fs/super.c:1751
fc_mount fs/namespace.c:1199 [inline]
do_new_mount_fc fs/namespace.c:3636 [inline]
do_new_mount+0x302/0xa10 fs/namespace.c:3712
do_mount fs/namespace.c:4035 [inline]
__do_sys_mount fs/namespace.c:4224 [inline]
__se_sys_mount+0x313/0x410 fs/namespace.c:4201
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (btrfs_trans_num_writers){++++}-{0:0}:
join_transaction+0x182/0xd60 fs/btrfs/transaction.c:322
start_transaction+0x6b7/0x15f0 fs/btrfs/transaction.c:707
btrfs_rebuild_free_space_tree+0xad/0x6c0 fs/btrfs/free-space-tree.c:1330
btrfs_start_pre_rw_mount+0x128f/0x1bf0 fs/btrfs/disk-io.c:3052
open_ctree+0x2b11/0x3d20 fs/btrfs/disk-io.c:3603
btrfs_fill_super fs/btrfs/super.c:983 [inline]
btrfs_get_tree_super fs/btrfs/super.c:1946 [inline]
btrfs_get_tree_subvol fs/btrfs/super.c:2089 [inline]
btrfs_get_tree+0x1061/0x1920 fs/btrfs/super.c:2123
vfs_get_tree+0x92/0x2a0 fs/super.c:1751
fc_mount fs/namespace.c:1199 [inline]
do_new_mount_fc fs/namespace.c:3636 [inline]
do_new_mount+0x302/0xa10 fs/namespace.c:3712
do_mount fs/namespace.c:4035 [inline]
__do_sys_mount fs/namespace.c:4224 [inline]
__se_sys_mount+0x313/0x410 fs/namespace.c:4201
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (sb_internal#2){.+.+}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868
percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
__sb_start_write include/linux/fs/super.h:19 [inline]
sb_start_intwrite include/linux/fs/super.h:177 [inline]
start_transaction+0x56f/0x15f0 fs/btrfs/transaction.c:701
btrfs_commit_inode_delayed_inode+0x117/0x2b0 fs/btrfs/delayed-inode.c:1279
btrfs_evict_inode+0x94c/0x1050 fs/btrfs/inode.c:5564
evict+0x5f4/0xae0 fs/inode.c:837
__dentry_kill+0x209/0x660 fs/dcache.c:670
finish_dput+0xc9/0x480 fs/dcache.c:879
ovl_stack_put+0x6a/0xa0 fs/overlayfs/util.c:133
ovl_destroy_inode+0xaa/0x150 fs/overlayfs/super.c:218
destroy_inode fs/inode.c:396 [inline]
evict+0x8aa/0xae0 fs/inode.c:861
__dentry_kill+0x209/0x660 fs/dcache.c:670
shrink_kill+0xa9/0x2c0 fs/dcache.c:1137
shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1164
prune_dcache_sb+0x10e/0x180 fs/dcache.c:1246
super_cache_scan+0x369/0x4b0 fs/super.c:222
do_shrink_slab+0x6df/0x10d0 mm/shrinker.c:437
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628
shrink_one+0x2d9/0x720 mm/vmscan.c:4919
shrink_many mm/vmscan.c:4980 [inline]
lru_gen_shrink_node mm/vmscan.c:5058 [inline]
shrink_node+0x2f7d/0x35b0 mm/vmscan.c:6045
kswapd_shrink_node mm/vmscan.c:6899 [inline]
balance_pgdat mm/vmscan.c:7082 [inline]
kswapd+0x145a/0x2820 mm/vmscan.c:7352
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
other info that might help us debug this:
Chain exists of:
sb_internal#2 --> &fs_info->qgroup_ioctl_lock --> fs_reclaim
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&fs_info->qgroup_ioctl_lock);
lock(fs_reclaim);
rlock(sb_internal#2);
*** DEADLOCK ***
2 locks held by kswapd0/78:
#0: ffffffff8e251780 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6973 [inline]
#0: ffffffff8e251780 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x92a/0x2820 mm/vmscan.c:7352
#1: ffff88801236e0e0 (&type->s_umount_key#53){.+.+}-{4:4}, at: super_trylock_shared fs/super.c:563 [inline]
#1: ffff88801236e0e0 (&type->s_umount_key#53){.+.+}-{4:4}, at: super_cache_scan+0x91/0x4b0 fs/super.c:197
stack backtrace:
CPU: 0 UID: 0 PID: 78 Comm: kswapd0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043
check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868
percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
__sb_start_write include/linux/fs/super.h:19 [inline]
sb_start_intwrite include/linux/fs/super.h:177 [inline]
start_transaction+0x56f/0x15f0 fs/btrfs/transaction.c:701
btrfs_commit_inode_delayed_inode+0x117/0x2b0 fs/btrfs/delayed-inode.c:1279
btrfs_evict_inode+0x94c/0x1050 fs/btrfs/inode.c:5564
evict+0x5f4/0xae0 fs/inode.c:837
__dentry_kill+0x209/0x660 fs/dcache.c:670
finish_dput+0xc9/0x480 fs/dcache.c:879
ovl_stack_put+0x6a/0xa0 fs/overlayfs/util.c:133
ovl_destroy_inode+0xaa/0x150 fs/overlayfs/super.c:218
destroy_inode fs/inode.c:396 [inline]
evict+0x8aa/0xae0 fs/inode.c:861
__dentry_kill+0x209/0x660 fs/dcache.c:670
shrink_kill+0xa9/0x2c0 fs/dcache.c:1137
shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1164
prune_dcache_sb+0x10e/0x180 fs/dcache.c:1246
super_cache_scan+0x369/0x4b0 fs/super.c:222
do_shrink_slab+0x6df/0x10d0 mm/shrinker.c:437
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628
shrink_one+0x2d9/0x720 mm/vmscan.c:4919
shrink_many mm/vmscan.c:4980 [inline]
lru_gen_shrink_node mm/vmscan.c:5058 [inline]
shrink_node+0x2f7d/0x35b0 mm/vmscan.c:6045
kswapd_shrink_node mm/vmscan.c:6899 [inline]
balance_pgdat mm/vmscan.c:7082 [inline]
kswapd+0x145a/0x2820 mm/vmscan.c:7352
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</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.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
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