====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.4.1546/9168 is trying to acquire lock: ffff88802987d8f0 (&ptp->n_vclocks_mux){+.+.}-{3:3}, at: ptp_vclock_in_use drivers/ptp/ptp_private.h:104 [inline] ffff88802987d8f0 (&ptp->n_vclocks_mux){+.+.}-{3:3}, at: ptp_clock_freerun drivers/ptp/ptp_private.h:121 [inline] ffff88802987d8f0 (&ptp->n_vclocks_mux){+.+.}-{3:3}, at: ptp_clock_adjtime+0x12f/0x870 drivers/ptp/ptp_clock.c:111 but task is already holding lock: ffff88802987c130 (&clk->rwsem){++++}-{3:3}, at: get_posix_clock kernel/time/posix-clock.c:25 [inline] ffff88802987c130 (&clk->rwsem){++++}-{3:3}, at: get_clock_desc kernel/time/posix-clock.c:232 [inline] ffff88802987c130 (&clk->rwsem){++++}-{3:3}, at: pc_clock_adjtime+0xde/0x260 kernel/time/posix-clock.c:252 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&clk->rwsem){++++}-{3:3}: down_write+0x36/0x60 kernel/locking/rwsem.c:1573 posix_clock_unregister+0x5b/0xc0 kernel/time/posix-clock.c:207 ptp_clock_unregister+0x18a/0x200 drivers/ptp/ptp_clock.c:391 ptp_vclock_unregister+0x110/0x140 drivers/ptp/ptp_vclock.c:230 unregister_vclock+0xca/0x130 drivers/ptp/ptp_sysfs.c:164 device_for_each_child_reverse+0x112/0x1b0 drivers/base/core.c:4073 n_vclocks_store+0x226/0x750 drivers/ptp/ptp_sysfs.c:228 kernfs_fop_write_iter+0x3a0/0x520 fs/kernfs/file.c:352 call_write_iter include/linux/fs.h:2271 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x482/0x9a0 fs/read_write.c:584 ksys_write+0x14d/0x260 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (&ptp->n_vclocks_mux){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5678 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 ptp_vclock_in_use drivers/ptp/ptp_private.h:104 [inline] ptp_clock_freerun drivers/ptp/ptp_private.h:121 [inline] ptp_clock_adjtime+0x12f/0x870 drivers/ptp/ptp_clock.c:111 pc_clock_adjtime+0x1d4/0x260 kernel/time/posix-clock.c:262 do_clock_adjtime kernel/time/posix-timers.c:1155 [inline] __do_sys_clock_adjtime kernel/time/posix-timers.c:1167 [inline] __se_sys_clock_adjtime kernel/time/posix-timers.c:1158 [inline] __x64_sys_clock_adjtime+0x240/0x320 kernel/time/posix-timers.c:1158 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&clk->rwsem); lock(&ptp->n_vclocks_mux); lock(&clk->rwsem); lock(&ptp->n_vclocks_mux); *** DEADLOCK *** 1 lock held by syz.4.1546/9168: #0: ffff88802987c130 (&clk->rwsem){++++}-{3:3}, at: get_posix_clock kernel/time/posix-clock.c:25 [inline] #0: ffff88802987c130 (&clk->rwsem){++++}-{3:3}, at: get_clock_desc kernel/time/posix-clock.c:232 [inline] #0: ffff88802987c130 (&clk->rwsem){++++}-{3:3}, at: pc_clock_adjtime+0xde/0x260 kernel/time/posix-clock.c:252 stack backtrace: CPU: 1 PID: 9168 Comm: syz.4.1546 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5678 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 ptp_vclock_in_use drivers/ptp/ptp_private.h:104 [inline] ptp_clock_freerun drivers/ptp/ptp_private.h:121 [inline] ptp_clock_adjtime+0x12f/0x870 drivers/ptp/ptp_clock.c:111 pc_clock_adjtime+0x1d4/0x260 kernel/time/posix-clock.c:262 do_clock_adjtime kernel/time/posix-timers.c:1155 [inline] __do_sys_clock_adjtime kernel/time/posix-timers.c:1167 [inline] __se_sys_clock_adjtime kernel/time/posix-timers.c:1158 [inline] __x64_sys_clock_adjtime+0x240/0x320 kernel/time/posix-timers.c:1158 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f6cecf9e159 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:00007f6cede03028 EFLAGS: 00000246 ORIG_RAX: 0000000000000131 RAX: ffffffffffffffda RBX: 00007f6ced225fa0 RCX: 00007f6cecf9e159 RDX: 0000000000000000 RSI: 0000200000000000 RDI: 00000000ffffffd3 RBP: 00007f6ced03506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6ced226038 R14: 00007f6ced225fa0 R15: 00007ffeb951f608 ptp: physical clock is free running