====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.565/7307 is trying to acquire lock: ffff888057f25c80 (&of->mutex){+.+.}-{4:4}, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:165 but task is already holding lock: ffff88803394b878 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x1270 fs/seq_file.c:183 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&p->lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821 seq_read_iter+0xe1/0x1270 fs/seq_file.c:183 proc_reg_read_iter+0x11b/0x310 fs/proc/inode.c:295 copy_splice_read+0x4ba/0xb90 fs/splice.c:362 do_splice_read fs/splice.c:980 [inline] do_splice_read+0x285/0x370 fs/splice.c:954 splice_file_to_pipe+0x82/0x120 fs/splice.c:1318 do_splice+0xda7/0x2090 fs/splice.c:1402 __do_splice+0x113/0x370 fs/splice.c:1459 __do_sys_splice fs/splice.c:1662 [inline] __se_sys_splice fs/splice.c:1644 [inline] __x64_sys_splice+0x187/0x250 fs/splice.c:1644 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x7b0 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&pipe->mutex){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821 anon_pipe_prefill_and_lock+0x16c/0x580 fs/pipe.c:165 anon_pipe_write+0x164/0x1bb0 fs/pipe.c:534 __kernel_write_iter+0x6b2/0x920 fs/read_write.c:621 __kernel_write+0xf6/0x140 fs/read_write.c:641 autofs_write fs/autofs/waitq.c:70 [inline] autofs_notify_daemon+0x51e/0xe00 fs/autofs/waitq.c:177 autofs_wait+0x10f8/0x1b30 fs/autofs/waitq.c:439 autofs_mount_wait+0x132/0x3b0 fs/autofs/root.c:256 autofs_d_automount+0x490/0x950 fs/autofs/root.c:410 follow_automount fs/namei.c:1571 [inline] __traverse_mounts+0x1b9/0x8a0 fs/namei.c:1624 traverse_mounts fs/namei.c:1653 [inline] handle_mounts fs/namei.c:1755 [inline] step_into_slowpath+0xb7e/0xf90 fs/namei.c:2110 step_into fs/namei.c:2158 [inline] walk_component fs/namei.c:2294 [inline] link_path_walk+0xe4a/0x1bd0 fs/namei.c:2662 path_lookupat+0x74/0xc40 fs/namei.c:2818 filename_lookup+0x202/0x590 fs/namei.c:2848 user_path_at+0x3c/0x60 fs/namei.c:3647 do_mount fs/namespace.c:4347 [inline] __do_sys_mount fs/namespace.c:4565 [inline] __se_sys_mount fs/namespace.c:4542 [inline] __x64_sys_mount+0x1fb/0x310 fs/namespace.c:4542 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x7b0 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&sbi->pipe_mutex){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821 autofs_write fs/autofs/waitq.c:68 [inline] autofs_notify_daemon+0x509/0xe00 fs/autofs/waitq.c:177 autofs_wait+0x10f8/0x1b30 fs/autofs/waitq.c:439 autofs_mount_wait+0x132/0x3b0 fs/autofs/root.c:256 autofs_d_automount+0x490/0x950 fs/autofs/root.c:410 follow_automount fs/namei.c:1571 [inline] __traverse_mounts+0x1b9/0x8a0 fs/namei.c:1624 traverse_mounts fs/namei.c:1653 [inline] handle_mounts fs/namei.c:1755 [inline] step_into_slowpath+0xb7e/0xf90 fs/namei.c:2110 step_into fs/namei.c:2158 [inline] walk_component fs/namei.c:2294 [inline] lookup_last fs/namei.c:2795 [inline] path_lookupat+0x58b/0xc40 fs/namei.c:2819 filename_lookup+0x202/0x590 fs/namei.c:2848 kern_path+0x37/0x50 fs/namei.c:3042 lookup_bdev+0xd8/0x2a0 block/bdev.c:1268 resume_store+0x1f5/0x480 kernel/power/hibernate.c:1286 kobj_attr_store+0x58/0x80 lib/kobject.c:842 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6af/0x1040 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x7b0 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&of->mutex){+.+.}-{4:4}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821 kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:165 seq_read_iter+0x2c1/0x1270 fs/seq_file.c:226 kernfs_fop_read_iter+0x46c/0x610 fs/kernfs/file.c:290 copy_splice_read+0x4ba/0xb90 fs/splice.c:362 do_splice_read fs/splice.c:980 [inline] do_splice_read+0x285/0x370 fs/splice.c:954 splice_direct_to_actor+0x29d/0xa30 fs/splice.c:1077 do_splice_direct_actor fs/splice.c:1230 [inline] do_splice_direct+0x174/0x240 fs/splice.c:1256 do_sendfile+0xadc/0xe20 fs/read_write.c:1371 __do_sys_sendfile64 fs/read_write.c:1432 [inline] __se_sys_sendfile64 fs/read_write.c:1418 [inline] __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1418 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x7b0 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &of->mutex --> &pipe->mutex --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(&pipe->mutex); lock(&p->lock); lock(&of->mutex); *** DEADLOCK *** locks held by syz.2.565/7307: 1, on CPU#1: #0: ffff88803394b878 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x1270 fs/seq_file.c:183 stack backtrace: CPU: 1 UID: 0 PID: 7307 Comm: syz.2.565 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2087 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821 kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:165 seq_read_iter+0x2c1/0x1270 fs/seq_file.c:226 kernfs_fop_read_iter+0x46c/0x610 fs/kernfs/file.c:290 copy_splice_read+0x4ba/0xb90 fs/splice.c:362 do_splice_read fs/splice.c:980 [inline] do_splice_read+0x285/0x370 fs/splice.c:954 splice_direct_to_actor+0x29d/0xa30 fs/splice.c:1077 do_splice_direct_actor fs/splice.c:1230 [inline] do_splice_direct+0x174/0x240 fs/splice.c:1256 do_sendfile+0xadc/0xe20 fs/read_write.c:1371 __do_sys_sendfile64 fs/read_write.c:1432 [inline] __se_sys_sendfile64 fs/read_write.c:1418 [inline] __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1418 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x7b0 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0f415a8f19 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0f4240d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f0f41826090 RCX: 00007f0f415a8f19 RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000007 RBP: 00007f0f41637f6d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f0f41826128 R14: 00007f0f41826090 R15: 00007ffda556a998