syzbot


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: 11d, last: 6d09h
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
b8ab3f0a-c61e-4c26-b848-ff9e376181c8 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 0e4b3e40a4572a10f991eaf3b70977db43e1fa9b
failed to run ["git" "-c" "core.hooksPath=/dev/null" "fetch" "--force" "--tags" "433dfd5a8a5d80bbf0669b14e9ed908911a52dd6" "596d152bc5e34b870b32ba3c6d6a766d563ebda0"]: exit status 128
error: insuffici...
truncated to first 200 bytes; open job for full error
bd5c39f0-2037-455c-830a-94e4947b9c8d 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 4f06757f683a802254a4c8edbfe67ff801904c5e
failed to run ["git" "-c" "core.hooksPath=/dev/null" "checkout" "596d152bc5e34b870b32ba3c6d6a766d563ebda0"]: exit status 128
fatal: unable to read tree (8c0e9110d5746386621b881b9e72384d6faee05d)
Duplicate of
Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported
possible deadlock in lock_two_nondirectories (2) overlayfs ext4 prio:high 4 C error 15 7h27m 20d
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 812d 808d 0/29 closed as dup on 2024/04/08 10:02
linux-4.14 possible deadlock in ovl_copy_up_start (2) 4 6 1619d 1669d 0/1 auto-closed as invalid on 2022/05/17 06:42
upstream possible deadlock in ovl_copy_up_start (2) overlayfs 4 1 1004d 1000d 0/29 closed as dup on 2023/10/04 08:46
linux-4.14 possible deadlock in ovl_copy_up_start (4) 4 1 1237d 1237d 0/1 upstream: reported on 2023/02/03 17:59
upstream possible deadlock in ovl_copy_up_start (4) overlayfs 4 7 745d 743d 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 1408d 1434d 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 1880d 2088d 0/1 auto-closed as invalid on 2021/08/29 09:58
upstream possible deadlock in ovl_copy_up_start overlayfs 4 2 2799d 2807d 11/29 fixed on 2018/11/12 21:25

Sample crash report:
EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.3.850/9421 is trying to acquire lock:
ffff0000f11ba5a0 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline]
ffff0000f11ba5a0 (&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:
ffff0000f3d85e58 (&ovl_i_mutex_key[depth]/4){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1074 [inline]
ffff0000f3d85e58 (&ovl_i_mutex_key[depth]/4){+.+.}-{4:4}, at: lock_two_nondirectories+0xe8/0x148 fs/inode.c:1256

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&ovl_i_mutex_key[depth]/4){+.+.}-{4:4}:
       __lock_release kernel/locking/lockdep.c:5574 [inline]
       lock_release+0x178/0x3b0 kernel/locking/lockdep.c:5889
       up_write+0x38/0x5cc kernel/locking/rwsem.c:1681
       inode_unlock include/linux/fs.h:1039 [inline]
       unlock_two_nondirectories+0x60/0x118 fs/inode.c:1269
       ext4_move_extents+0x3e4/0x3324 fs/ext4/move_extent.c:656
       __ext4_ioctl fs/ext4/ioctl.c:1657 [inline]
       ext4_ioctl+0x2a10/0x4280 fs/ext4/ioctl.c:1922
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl fs/ioctl.c:583 [inline]
       __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583
       __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#3){.+.+}-{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+0x5c/0x294 include/linux/fs/super.h:125
       mnt_want_write+0x44/0x9c fs/namespace.c:493
       ovl_want_write fs/overlayfs/util.c:38 [inline]
       ovl_nlink_start+0x154/0x350 fs/overlayfs/util.c:1177
       ovl_do_remove+0x1c4/0x980 fs/overlayfs/dir.c:954
       ovl_rmdir+0x24/0x34 fs/overlayfs/dir.c:993
       vfs_rmdir+0x354/0x590 fs/namei.c:5376
       filename_rmdir+0x208/0x3d0 fs/namei.c:5431
       __do_sys_unlinkat fs/namei.c:5606 [inline]
       __se_sys_unlinkat fs/namei.c:5599 [inline]
       __arm64_sys_unlinkat+0xc8/0x104 fs/namei.c:5599
       __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_rename_start fs/overlayfs/dir.c:1185 [inline]
       ovl_rename+0x3d4/0xf80 fs/overlayfs/dir.c:1363
       vfs_rename+0xa78/0xd48 fs/namei.c:6064
       filename_renameat2+0x660/0x72c fs/namei.c:6182
       __do_sys_renameat2 fs/namei.c:6211 [inline]
       __se_sys_renameat2 fs/namei.c:6206 [inline]
       __arm64_sys_renameat2+0xec/0x11c fs/namei.c:6206
       __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] --> sb_writers#3 --> &ovl_i_mutex_key[depth]/4

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ovl_i_mutex_key[depth]/4);
                               lock(sb_writers#3);
                               lock(&ovl_i_mutex_key[depth]/4);
  lock(&ovl_i_lock_key[depth]);

 *** DEADLOCK ***

4 locks held by syz.3.850/9421:
 #0: ffff0000dc0a0410 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:493
 #1: ffff0000f3d81740 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1074 [inline]
 #1: ffff0000f3d81740 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3787 [inline]
 #1: ffff0000f3d81740 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: __start_renaming+0x144/0x344 fs/namei.c:3880
 #2: ffff0000f11ba230 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline]
 #2: ffff0000f11ba230 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}, at: lock_two_nondirectories+0xc4/0x148 fs/inode.c:1254
 #3: ffff0000f3d85e58 (&ovl_i_mutex_key[depth]/4){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1074 [inline]
 #3: ffff0000f3d85e58 (&ovl_i_mutex_key[depth]/4){+.+.}-{4:4}, at: lock_two_nondirectories+0xe8/0x148 fs/inode.c:1256

stack backtrace:
CPU: 1 UID: 0 PID: 9421 Comm: syz.3.850 Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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_rename_start fs/overlayfs/dir.c:1185 [inline]
 ovl_rename+0x3d4/0xf80 fs/overlayfs/dir.c:1363
 vfs_rename+0xa78/0xd48 fs/namei.c:6064
 filename_renameat2+0x660/0x72c fs/namei.c:6182
 __do_sys_renameat2 fs/namei.c:6211 [inline]
 __se_sys_renameat2 fs/namei.c:6206 [inline]
 __arm64_sys_renameat2+0xec/0x11c fs/namei.c:6206
 __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 (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.