Hello, syzbot found the following issue on: HEAD commit: 0d8d44db295c Merge tag 'for-6.15-rc5-tag' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1236fb68580000 kernel config: https://syzkaller.appspot.com/x/.config?x=b39cb28b0a399ed3 dashboard link: https://syzkaller.appspot.com/bug?extid=247d7a192c296bf9769c compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/5536cda9f25f/disk-0d8d44db.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/92d52f7afb23/vmlinux-0d8d44db.xz kernel image: https://storage.googleapis.com/syzbot-assets/a31f0b2e7b87/bzImage-0d8d44db.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+247d7a192c296bf9769c@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc5-syzkaller-00032-g0d8d44db295c #0 Not tainted ------------------------------------------------------ syz.4.1562/14048 is trying to acquire lock: ffff88807af9fc68 (&pipe->mutex){+.+.}-{4:4}, at: anon_pipe_write+0x15d/0x1a70 fs/pipe.c:459 but task is already holding lock: ffff8880588b8140 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_write fs/autofs/waitq.c:55 [inline] ffff8880588b8140 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_notify_daemon+0x4a6/0xd60 fs/autofs/waitq.c:164 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sbi->pipe_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 autofs_write fs/autofs/waitq.c:55 [inline] autofs_notify_daemon+0x4a6/0xd60 fs/autofs/waitq.c:164 autofs_wait+0x10ca/0x1a70 fs/autofs/waitq.c:426 autofs_mount_wait+0x132/0x380 fs/autofs/root.c:255 autofs_d_automount+0x390/0x7f0 fs/autofs/root.c:401 follow_automount fs/namei.c:1455 [inline] __traverse_mounts+0x192/0x790 fs/namei.c:1500 traverse_mounts fs/namei.c:1529 [inline] handle_mounts fs/namei.c:1632 [inline] step_into+0x5aa/0x2270 fs/namei.c:1976 walk_component+0xfc/0x5b0 fs/namei.c:2144 lookup_last fs/namei.c:2636 [inline] path_lookupat+0x17e/0x780 fs/namei.c:2660 filename_lookup+0x224/0x5f0 fs/namei.c:2689 kern_path+0x35/0x50 fs/namei.c:2822 lookup_bdev+0xd8/0x280 block/bdev.c:1205 resume_store+0x1d6/0x460 kernel/power/hibernate.c:1248 kobj_attr_store+0x55/0x80 lib/kobject.c:840 sysfs_kf_write+0xef/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x351/0x510 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:591 [inline] vfs_write+0x5ba/0x1180 fs/read_write.c:684 ksys_write+0x12a/0x240 fs/read_write.c:736 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&of->mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 kernfs_fop_write_iter+0x28f/0x510 fs/kernfs/file.c:325 iter_file_splice_write+0x91c/0x1150 fs/splice.c:738 do_splice_from fs/splice.c:935 [inline] do_splice+0x1475/0x1fc0 fs/splice.c:1348 __do_splice+0x32a/0x360 fs/splice.c:1430 __do_sys_splice fs/splice.c:1633 [inline] __se_sys_splice fs/splice.c:1615 [inline] __x64_sys_splice+0x187/0x250 fs/splice.c:1615 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&pipe->mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 anon_pipe_write+0x15d/0x1a70 fs/pipe.c:459 __kernel_write_iter+0x71d/0xa90 fs/read_write.c:617 __kernel_write+0xf5/0x140 fs/read_write.c:637 autofs_write fs/autofs/waitq.c:57 [inline] autofs_notify_daemon+0x4db/0xd60 fs/autofs/waitq.c:164 autofs_wait+0x10ca/0x1a70 fs/autofs/waitq.c:426 autofs_mount_wait+0x132/0x380 fs/autofs/root.c:255 autofs_d_automount+0x390/0x7f0 fs/autofs/root.c:401 follow_automount fs/namei.c:1455 [inline] __traverse_mounts+0x192/0x790 fs/namei.c:1500 traverse_mounts fs/namei.c:1529 [inline] handle_mounts fs/namei.c:1632 [inline] step_into+0x5aa/0x2270 fs/namei.c:1976 walk_component+0xfc/0x5b0 fs/namei.c:2144 lookup_last fs/namei.c:2636 [inline] path_lookupat+0x17e/0x780 fs/namei.c:2660 filename_lookup+0x224/0x5f0 fs/namei.c:2689 user_path_at+0x3a/0x60 fs/namei.c:3120 do_mount fs/namespace.c:4221 [inline] __do_sys_mount fs/namespace.c:4435 [inline] __se_sys_mount fs/namespace.c:4412 [inline] __x64_sys_mount+0x1fc/0x310 fs/namespace.c:4412 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 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: &pipe->mutex --> &of->mutex --> &sbi->pipe_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sbi->pipe_mutex); lock(&of->mutex); lock(&sbi->pipe_mutex); lock(&pipe->mutex); *** DEADLOCK *** 1 lock held by syz.4.1562/14048: #0: ffff8880588b8140 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_write fs/autofs/waitq.c:55 [inline] #0: ffff8880588b8140 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_notify_daemon+0x4a6/0xd60 fs/autofs/waitq.c:164 stack backtrace: CPU: 1 UID: 0 PID: 14048 Comm: syz.4.1562 Not tainted 6.15.0-rc5-syzkaller-00032-g0d8d44db295c #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2079 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 anon_pipe_write+0x15d/0x1a70 fs/pipe.c:459 __kernel_write_iter+0x71d/0xa90 fs/read_write.c:617 __kernel_write+0xf5/0x140 fs/read_write.c:637 autofs_write fs/autofs/waitq.c:57 [inline] autofs_notify_daemon+0x4db/0xd60 fs/autofs/waitq.c:164 autofs_wait+0x10ca/0x1a70 fs/autofs/waitq.c:426 autofs_mount_wait+0x132/0x380 fs/autofs/root.c:255 autofs_d_automount+0x390/0x7f0 fs/autofs/root.c:401 follow_automount fs/namei.c:1455 [inline] __traverse_mounts+0x192/0x790 fs/namei.c:1500 traverse_mounts fs/namei.c:1529 [inline] handle_mounts fs/namei.c:1632 [inline] step_into+0x5aa/0x2270 fs/namei.c:1976 walk_component+0xfc/0x5b0 fs/namei.c:2144 lookup_last fs/namei.c:2636 [inline] path_lookupat+0x17e/0x780 fs/namei.c:2660 filename_lookup+0x224/0x5f0 fs/namei.c:2689 user_path_at+0x3a/0x60 fs/namei.c:3120 do_mount fs/namespace.c:4221 [inline] __do_sys_mount fs/namespace.c:4435 [inline] __se_sys_mount fs/namespace.c:4412 [inline] __x64_sys_mount+0x1fc/0x310 fs/namespace.c:4412 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7faef658e969 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:00007faef7347038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007faef67b5fa0 RCX: 00007faef658e969 RDX: 0000000000000000 RSI: 00002000000001c0 RDI: 0000000000000000 RBP: 00007faef6610ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000010000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007faef67b5fa0 R15: 00007ffeefd9fb38 </TASK> --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
