syzbot


possible deadlock in xfs_ilock (4)

Status: upstream: reported on 2026/01/05 02:40
Subsystems: xfs
[Documentation on labels]
Reported-by: syzbot+c628140f24c07eb768d8@syzkaller.appspotmail.com
First crash: 13d, last: 13d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [xfs?] possible deadlock in xfs_ilock (4) 4 (6) 2026/01/06 13:35
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in xfs_ilock (3) xfs 4 3 381d 422d 0/29 auto-obsoleted due to no activity on 2025/04/07 15:47
upstream possible deadlock in xfs_ilock (2) xfs 4 1422 567d 639d 0/29 auto-obsoleted due to no activity on 2024/09/04 06:27
upstream possible deadlock in xfs_ilock xfs 4 30 644d 670d 25/29 fixed on 2024/04/10 03:59

Sample crash report:
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.4/6790 is trying to acquire lock:
ffff80008fb56c80 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:317 [inline]
ffff80008fb56c80 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4904 [inline]
ffff80008fb56c80 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:5239 [inline]
ffff80008fb56c80 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_cache_noprof+0x58/0x698 mm/slub.c:5771

but task is already holding lock:
ffff0000f77f5b18 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_ilock+0x1d8/0x3d0 fs/xfs/xfs_inode.c:165

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&xfs_nondir_ilock_class){++++}-{4:4}:
       down_write_nested+0x58/0xcc kernel/locking/rwsem.c:1706
       xfs_ilock+0x1d8/0x3d0 fs/xfs/xfs_inode.c:165
       xfs_reclaim_inode fs/xfs/xfs_icache.c:1035 [inline]
       xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1727 [inline]
       xfs_icwalk_ag+0xe4c/0x16a4 fs/xfs/xfs_icache.c:1809
       xfs_icwalk fs/xfs/xfs_icache.c:1857 [inline]
       xfs_reclaim_inodes_nr+0x1b4/0x268 fs/xfs/xfs_icache.c:1101
       xfs_fs_free_cached_objects+0x68/0x7c fs/xfs/xfs_super.c:1282
       super_cache_scan+0x2f0/0x380 fs/super.c:228
       do_shrink_slab+0x638/0x11b0 mm/shrinker.c:437
       shrink_slab+0xc68/0xfb8 mm/shrinker.c:664
       shrink_node_memcgs mm/vmscan.c:6022 [inline]
       shrink_node+0xe18/0x20bc mm/vmscan.c:6061
       kswapd_shrink_node mm/vmscan.c:6901 [inline]
       balance_pgdat+0xb60/0x13b8 mm/vmscan.c:7084
       kswapd+0x6d0/0xe64 mm/vmscan.c:7354
       kthread+0x5fc/0x75c kernel/kthread.c:463
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844

-> #0 (fs_reclaim){+.+.}-{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+0x1774/0x30a4 kernel/locking/lockdep.c:5237
       lock_acquire+0x140/0x2e0 kernel/locking/lockdep.c:5868
       __fs_reclaim_acquire mm/page_alloc.c:4301 [inline]
       fs_reclaim_acquire+0x8c/0x118 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+0x58/0x698 mm/slub.c:5771
       kmalloc_noprof include/linux/slab.h:957 [inline]
       iomap_fill_dirty_folios+0xf0/0x218 fs/iomap/buffered-io.c:1557
       xfs_buffered_write_iomap_begin+0x8b4/0x1668 fs/xfs/xfs_iomap.c:1857
       iomap_iter+0x528/0xefc fs/iomap/iter.c:110
       iomap_zero_range+0x17c/0x8ec fs/iomap/buffered-io.c:1590
       xfs_zero_range+0x98/0xfc fs/xfs/xfs_iomap.c:2289
       xfs_reflink_zero_posteof+0x110/0x2f0 fs/xfs/xfs_reflink.c:1619
       xfs_reflink_remap_prep+0x314/0x5e4 fs/xfs/xfs_reflink.c:1699
       xfs_file_remap_range+0x1f4/0x758 fs/xfs/xfs_file.c:1518
       vfs_clone_file_range+0x62c/0xb68 fs/remap_range.c:403
       ioctl_file_clone fs/ioctl.c:239 [inline]
       ioctl_file_clone_range fs/ioctl.c:257 [inline]
       do_vfs_ioctl+0xb84/0x1834 fs/ioctl.c:544
       __do_sys_ioctl fs/ioctl.c:595 [inline]
       __se_sys_ioctl fs/ioctl.c:583 [inline]
       __arm64_sys_ioctl+0xe4/0x1c4 fs/ioctl.c:583
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724
       el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&xfs_nondir_ilock_class);
                               lock(fs_reclaim);
                               lock(&xfs_nondir_ilock_class);
  lock(fs_reclaim);

 *** DEADLOCK ***

4 locks held by syz.3.4/6790:
 #0: ffff0000dceca420 (sb_writers#13){.+.+}-{0:0}, at: ioctl_file_clone fs/ioctl.c:239 [inline]
 #0: ffff0000dceca420 (sb_writers#13){.+.+}-{0:0}, at: ioctl_file_clone_range fs/ioctl.c:257 [inline]
 #0: ffff0000dceca420 (sb_writers#13){.+.+}-{0:0}, at: do_vfs_ioctl+0xb84/0x1834 fs/ioctl.c:544
 #1: ffff0000f77f5d30 (&sb->s_type->i_mutex_key#27){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
 #1: ffff0000f77f5d30 (&sb->s_type->i_mutex_key#27){+.+.}-{4:4}, at: xfs_iolock_two_inodes_and_break_layout fs/xfs/xfs_inode.c:2716 [inline]
 #1: ffff0000f77f5d30 (&sb->s_type->i_mutex_key#27){+.+.}-{4:4}, at: xfs_ilock2_io_mmap+0x1a4/0x64c fs/xfs/xfs_inode.c:2792
 #2: ffff0000f77f5ed0 (mapping.invalidate_lock#3){++++}-{4:4}, at: filemap_invalidate_lock_two+0x3c/0x84 mm/filemap.c:1032
 #3: ffff0000f77f5b18 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_ilock+0x1d8/0x3d0 fs/xfs/xfs_inode.c:165

stack backtrace:
CPU: 0 UID: 0 PID: 6790 Comm: syz.3.4 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2043
 check_noncircular+0x154/0x174 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+0x1774/0x30a4 kernel/locking/lockdep.c:5237
 lock_acquire+0x140/0x2e0 kernel/locking/lockdep.c:5868
 __fs_reclaim_acquire mm/page_alloc.c:4301 [inline]
 fs_reclaim_acquire+0x8c/0x118 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+0x58/0x698 mm/slub.c:5771
 kmalloc_noprof include/linux/slab.h:957 [inline]
 iomap_fill_dirty_folios+0xf0/0x218 fs/iomap/buffered-io.c:1557
 xfs_buffered_write_iomap_begin+0x8b4/0x1668 fs/xfs/xfs_iomap.c:1857
 iomap_iter+0x528/0xefc fs/iomap/iter.c:110
 iomap_zero_range+0x17c/0x8ec fs/iomap/buffered-io.c:1590
 xfs_zero_range+0x98/0xfc fs/xfs/xfs_iomap.c:2289
 xfs_reflink_zero_posteof+0x110/0x2f0 fs/xfs/xfs_reflink.c:1619
 xfs_reflink_remap_prep+0x314/0x5e4 fs/xfs/xfs_reflink.c:1699
 xfs_file_remap_range+0x1f4/0x758 fs/xfs/xfs_file.c:1518
 vfs_clone_file_range+0x62c/0xb68 fs/remap_range.c:403
 ioctl_file_clone fs/ioctl.c:239 [inline]
 ioctl_file_clone_range fs/ioctl.c:257 [inline]
 do_vfs_ioctl+0xb84/0x1834 fs/ioctl.c:544
 __do_sys_ioctl fs/ioctl.c:595 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __arm64_sys_ioctl+0xe4/0x1c4 fs/ioctl.c:583
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/01 02:33 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 8f0b4cce4481 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in xfs_ilock
* Struck through repros no longer work on HEAD.