possible deadlock in ovl_copy_up_start (5)

Status: closed as dup on 2026/06/18 10:47
Subsystems: overlayfs
[Documentation on labels]
Reported-by: syzbot+d4e3aadc5bd19f7e71ff@syzkaller.appspotmail.com
First crash: 62d, last: 48d
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
b8ab3f0a assessment-security 💥 possible deadlock in ovl_copy_up_start (5) 2026/06/17 00:02 2026/06/17 00:02 2026/06/17 00:02 0e4b3e40
bd5c39f0 assessment-security 💥 possible deadlock in ovl_copy_up_start (5) 2026/06/15 00:02 2026/06/15 00:02 2026/06/15 00:02 4f06757f
▶ ▼ Duplicate of
Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported
possible deadlock in lock_two_nondirectories (2) prio:high ext4 overlayfs 4 syz, C error 17 49d 71d
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [overlayfs?] possible deadlock in ovl_copy_up_start (5) 1 (2) 2026/06/18 10:47
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ovl_copy_up_start (3) overlayfs 4 1 863d 859d 0/29 closed as dup on 2024/04/08 10:02
linux-4.14 possible deadlock in ovl_copy_up_start (2) 4 6 1671d 1721d 0/1 auto-closed as invalid on 2022/05/17 06:42
upstream possible deadlock in ovl_copy_up_start (2) overlayfs 4 1 1055d 1051d 0/29 closed as dup on 2023/10/04 08:46
linux-4.14 possible deadlock in ovl_copy_up_start (4) 4 1 1288d 1288d 0/1 upstream: reported on 2023/02/03 17:59
upstream possible deadlock in ovl_copy_up_start (4) overlayfs 4 7 796d 794d 0/29 auto-obsoleted due to no activity on 2024/09/17 23:05
linux-4.14 possible deadlock in ovl_copy_up_start (3) 4 2 1459d 1485d 0/1 auto-obsoleted due to no activity on 2022/12/14 20:28
linux-4.14 possible deadlock in ovl_copy_up_start 4 9 1931d 2139d 0/1 auto-closed as invalid on 2021/08/29 09:58
upstream possible deadlock in ovl_copy_up_start overlayfs 4 2 2850d 2858d 11/29 fixed on 2018/11/12 21:25

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.5.973/15322 is trying to acquire lock:
ffff0000f31c8a48 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline]
ffff0000f31c8a48 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_copy_up_start+0x58/0x264 fs/overlayfs/util.c:735

but task is already holding lock:
ffff0000f31c86d8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline]
ffff0000f31c86d8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: vfs_setxattr+0x130/0x2e0 fs/xattr.c:338

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}:
       down_read+0x58/0x2bc kernel/locking/rwsem.c:1568
       inode_lock_shared include/linux/fs.h:1044 [inline]
       lookup_slow+0x50/0x84 fs/namei.c:1931
       walk_component fs/namei.c:2278 [inline]
       lookup_last fs/namei.c:2785 [inline]
       path_lookupat+0x358/0x798 fs/namei.c:2809
       filename_lookup+0x1d0/0x3c8 fs/namei.c:2838
       kern_path+0x4c/0x70 fs/namei.c:3044
       lookup_bdev+0xc0/0x248 block/bdev.c:1213
       resume_store+0x120/0x3e4 kernel/power/hibernate.c:1306
       kobj_attr_store+0x6c/0x90 lib/kobject.c:840
       sysfs_kf_write+0xe0/0x108 fs/sysfs/file.c:142
       kernfs_fop_write_iter+0x260/0x3b8 fs/kernfs/file.c:352
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x51c/0xa0c fs/read_write.c:688
       ksys_write+0x12c/0x228 fs/read_write.c:740
       __do_sys_write fs/read_write.c:751 [inline]
       __se_sys_write fs/read_write.c:748 [inline]
       __arm64_sys_write+0x7c/0x90 fs/read_write.c:748
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

-> #4 (&of->mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x164/0xed0 kernel/locking/mutex.c:820
       mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
       kernfs_seq_start+0x54/0x164 fs/kernfs/file.c:172
       seq_read_iter+0x340/0xbe8 fs/seq_file.c:226
       kernfs_fop_read_iter+0x13c/0x414 fs/kernfs/file.c:297
       copy_splice_read+0x4b8/0x8fc fs/splice.c:362
       do_splice_read+0x1c4/0x2e8 fs/splice.c:980
       splice_direct_to_actor+0x20c/0x7a8 fs/splice.c:1084
       do_splice_direct_actor+0x140/0x228 fs/splice.c:1202
       do_splice_direct+0x58/0x70 fs/splice.c:1228
       do_sendfile+0x40c/0x6c0 fs/read_write.c:1372
       __do_sys_sendfile64 fs/read_write.c:1433 [inline]
       __se_sys_sendfile64 fs/read_write.c:1419 [inline]
       __arm64_sys_sendfile64+0x1bc/0x284 fs/read_write.c:1419
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

-> #3 (&p->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x164/0xed0 kernel/locking/mutex.c:820
       mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
       seq_read_iter+0xb0/0xbe8 fs/seq_file.c:183
       copy_splice_read+0x4b8/0x8fc fs/splice.c:362
       do_splice_read+0x1c4/0x2e8 fs/splice.c:980
       splice_file_to_pipe+0x84/0xd4 fs/splice.c:1290
       do_sendfile+0x3b8/0x6c0 fs/read_write.c:1378
       __do_sys_sendfile64 fs/read_write.c:1433 [inline]
       __se_sys_sendfile64 fs/read_write.c:1419 [inline]
       __arm64_sys_sendfile64+0x1bc/0x284 fs/read_write.c:1419
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x19c/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

-> #2 (&pipe->mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x164/0xed0 kernel/locking/mutex.c:820
       mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
       pipe_lock+0x64/0x88 fs/pipe.c:91
       iter_file_splice_write+0x184/0xd50 fs/splice.c:682
       do_splice_from fs/splice.c:936 [inline]
       do_splice+0x9c0/0x1228 fs/splice.c:1349
       __do_splice fs/splice.c:1431 [inline]
       __do_sys_splice fs/splice.c:1634 [inline]
       __se_sys_splice fs/splice.c:1616 [inline]
       __arm64_sys_splice+0x2c0/0x4e4 fs/splice.c:1616
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

-> #1 (sb_writers#5){.+.+}-{0:0}:
       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_write include/linux/fs/super.h:125 [inline]
       ovl_start_write+0xf0/0x324 fs/overlayfs/util.c:32
       ovl_do_copy_up fs/overlayfs/copy_up.c:977 [inline]
       ovl_copy_up_one fs/overlayfs/copy_up.c:1189 [inline]
       ovl_copy_up_flags+0x988/0x28c0 fs/overlayfs/copy_up.c:1243
       ovl_maybe_copy_up+0x108/0x148 fs/overlayfs/copy_up.c:1272
       ovl_open+0x12c/0x2c0 fs/overlayfs/file.c:211
       do_dentry_open+0x5c4/0xfb8 fs/open.c:947
       vfs_open+0x44/0x2dc fs/open.c:1079
       do_open fs/namei.c:4699 [inline]
       path_openat+0x22d4/0x2b88 fs/namei.c:4858
       do_file_open+0x1c8/0x2e8 fs/namei.c:4887
       do_sys_openat2+0x114/0x1e8 fs/open.c:1364
       do_sys_open+0xac/0xdc fs/open.c:1370
       __do_sys_openat fs/open.c:1386 [inline]
       __se_sys_openat fs/open.c:1381 [inline]
       __arm64_sys_openat+0xa0/0xbc fs/open.c:1381
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

-> #0 (&ovl_i_lock_key[depth]){+.+.}-{4:4}:
       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+0x17c0/0x2ebc kernel/locking/lockdep.c:5237
       lock_acquire+0x140/0x364 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x164/0xed0 kernel/locking/mutex.c:820
       mutex_lock_interruptible_nested+0x24/0x30 kernel/locking/mutex.c:898
       ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline]
       ovl_copy_up_start+0x58/0x264 fs/overlayfs/util.c:735
       ovl_copy_up_one fs/overlayfs/copy_up.c:1182 [inline]
       ovl_copy_up_flags+0x770/0x28c0 fs/overlayfs/copy_up.c:1243
       ovl_copy_up+0x24/0x34 fs/overlayfs/copy_up.c:1282
       ovl_xattr_set+0x280/0x478 fs/overlayfs/xattrs.c:54
       ovl_own_xattr_set+0x9c/0xcc fs/overlayfs/xattrs.c:204
       __vfs_setxattr+0x130/0x17c fs/xattr.c:218
       __vfs_setxattr_noperm+0x120/0x5cc fs/xattr.c:252
       __vfs_setxattr_locked+0x114/0x240 fs/xattr.c:313
       vfs_setxattr+0x150/0x2e0 fs/xattr.c:339
       do_setxattr+0x100/0x19c fs/xattr.c:654
       filename_setxattr+0x134/0x1f8 fs/xattr.c:682
       path_setxattrat+0x200/0x2a8 fs/xattr.c:726
       __do_sys_setxattr fs/xattr.c:760 [inline]
       __se_sys_setxattr fs/xattr.c:756 [inline]
       __arm64_sys_setxattr+0xc8/0xe4 fs/xattr.c:756
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
       do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
       el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
       el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

other info that might help us debug this:

Chain exists of:
  &ovl_i_lock_key[depth] --> &of->mutex --> &ovl_i_mutex_dir_key[depth]

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ovl_i_mutex_dir_key[depth]);
                               lock(&of->mutex);
                               lock(&ovl_i_mutex_dir_key[depth]);
  lock(&ovl_i_lock_key[depth]);

 *** DEADLOCK ***

2 locks held by syz.5.973/15322:
 #0: ffff0000dc7de410 (sb_writers#20){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:493
 #1: ffff0000f31c86d8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline]
 #1: ffff0000f31c86d8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: vfs_setxattr+0x130/0x2e0 fs/xattr.c:338

stack backtrace:
CPU: 1 UID: 0 PID: 15322 Comm: syz.5.973 Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026
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+0x328/0x330 kernel/locking/lockdep.c:2043
 check_noncircular+0x158/0x174 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+0x17c0/0x2ebc kernel/locking/lockdep.c:5237
 lock_acquire+0x140/0x364 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x164/0xed0 kernel/locking/mutex.c:820
 mutex_lock_interruptible_nested+0x24/0x30 kernel/locking/mutex.c:898
 ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline]
 ovl_copy_up_start+0x58/0x264 fs/overlayfs/util.c:735
 ovl_copy_up_one fs/overlayfs/copy_up.c:1182 [inline]
 ovl_copy_up_flags+0x770/0x28c0 fs/overlayfs/copy_up.c:1243
 ovl_copy_up+0x24/0x34 fs/overlayfs/copy_up.c:1282
 ovl_xattr_set+0x280/0x478 fs/overlayfs/xattrs.c:54
 ovl_own_xattr_set+0x9c/0xcc fs/overlayfs/xattrs.c:204
 __vfs_setxattr+0x130/0x17c fs/xattr.c:218
 __vfs_setxattr_noperm+0x120/0x5cc fs/xattr.c:252
 __vfs_setxattr_locked+0x114/0x240 fs/xattr.c:313
 vfs_setxattr+0x150/0x2e0 fs/xattr.c:339
 do_setxattr+0x100/0x19c fs/xattr.c:654
 filename_setxattr+0x134/0x1f8 fs/xattr.c:682
 path_setxattrat+0x200/0x2a8 fs/xattr.c:726
 __do_sys_setxattr fs/xattr.c:760 [inline]
 __se_sys_setxattr fs/xattr.c:756 [inline]
 __arm64_sys_setxattr+0xc8/0xe4 fs/xattr.c:756
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/27 21:46 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 92e3f6ef4ffb fb92f11c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in ovl_copy_up_start
2026/06/18 20:16 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci c2a9495bd873 a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in ovl_copy_up_start
2026/06/13 20:59 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 596d152bc5e3 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in ovl_copy_up_start
* Struck through repros no longer work on HEAD.