====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.8.8338/2933 is trying to acquire lock: ffff888066ba7c88 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1de/0x540 fs/kernfs/file.c:343 but task is already holding lock: ffff88805a402068 (&pipe->mutex){+.+.}-{4:4}, at: iter_file_splice_write+0x1e3/0x10b0 fs/splice.c:683 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&pipe->mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x184/0x1300 kernel/locking/mutex.c:776 iter_file_splice_write+0x1e3/0x10b0 fs/splice.c:683 do_splice_from fs/splice.c:938 [inline] do_splice+0xc79/0x1660 fs/splice.c:1351 __do_splice fs/splice.c:1433 [inline] __do_sys_splice fs/splice.c:1636 [inline] __se_sys_splice+0x2e1/0x460 fs/splice.c:1618 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (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+0x4d/0x1c0 include/linux/fs/super.h:125 mnt_want_write+0x41/0x90 fs/namespace.c:504 ovl_create_object+0xfa/0x3b0 fs/overlayfs/dir.c:691 lookup_open fs/namei.c:4481 [inline] open_last_lookups fs/namei.c:4581 [inline] path_openat+0x1387/0x3840 fs/namei.c:4825 do_file_open+0x203/0x440 fs/namei.c:4857 do_sys_openat2+0x105/0x1e0 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_open fs/open.c:1380 [inline] __se_sys_open fs/open.c:1376 [inline] __x64_sys_open+0x11e/0x150 fs/open.c:1376 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}: down_read+0x47/0x2e0 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:1043 [inline] lookup_slow+0x46/0x70 fs/namei.c:1932 walk_component fs/namei.c:2279 [inline] lookup_last fs/namei.c:2780 [inline] path_lookupat+0x3f5/0x8c0 fs/namei.c:2804 filename_lookup+0x212/0x570 fs/namei.c:2833 kern_path+0x3d/0x150 fs/namei.c:3040 lookup_bdev+0xc0/0x280 block/bdev.c:1222 resume_store+0x169/0x480 kernel/power/hibernate.c:1306 kernfs_fop_write_iter+0x3af/0x540 fs/kernfs/file.c:352 iter_file_splice_write+0x972/0x10b0 fs/splice.c:738 do_splice_from fs/splice.c:938 [inline] direct_splice_actor+0x101/0x160 fs/splice.c:1161 splice_direct_to_actor+0x5a8/0xcc0 fs/splice.c:1105 do_splice_direct_actor fs/splice.c:1204 [inline] do_splice_direct+0x181/0x270 fs/splice.c:1230 do_sendfile+0x4da/0x7e0 fs/read_write.c:1372 __do_sys_sendfile64 fs/read_write.c:1433 [inline] __se_sys_sendfile64+0x13e/0x190 fs/read_write.c:1419 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&of->mutex){+.+.}-{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+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x184/0x1300 kernel/locking/mutex.c:776 kernfs_fop_write_iter+0x1de/0x540 fs/kernfs/file.c:343 iter_file_splice_write+0x972/0x10b0 fs/splice.c:738 do_splice_from fs/splice.c:938 [inline] do_splice+0xc79/0x1660 fs/splice.c:1351 __do_splice fs/splice.c:1433 [inline] __do_sys_splice fs/splice.c:1636 [inline] __se_sys_splice+0x2e1/0x460 fs/splice.c:1618 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &of->mutex --> sb_writers#5 --> &pipe->mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pipe->mutex); lock(sb_writers#5); lock(&pipe->mutex); lock(&of->mutex); *** DEADLOCK *** 2 locks held by syz.8.8338/2933: #0: ffff8880114ae420 (sb_writers#10){.+.+}-{0:0}, at: do_splice+0xbff/0x1660 fs/splice.c:1350 #1: ffff88805a402068 (&pipe->mutex){+.+.}-{4:4}, at: iter_file_splice_write+0x1e3/0x10b0 fs/splice.c:683 stack backtrace: CPU: 1 UID: 0 PID: 2933 Comm: syz.8.8338 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0xe8/0x150 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+0x107/0x340 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x184/0x1300 kernel/locking/mutex.c:776 kernfs_fop_write_iter+0x1de/0x540 fs/kernfs/file.c:343 iter_file_splice_write+0x972/0x10b0 fs/splice.c:738 do_splice_from fs/splice.c:938 [inline] do_splice+0xc79/0x1660 fs/splice.c:1351 __do_splice fs/splice.c:1433 [inline] __do_sys_splice fs/splice.c:1636 [inline] __se_sys_splice+0x2e1/0x460 fs/splice.c:1618 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1964f8f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f1965d3f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00007f19651e5fa0 RCX: 00007f1964f8f749 RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007f1965013f91 R08: 000000000000000c R09: 0000000000000003 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f19651e6038 R14: 00007f19651e5fa0 R15: 00007ffe8f6119c8