====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.1.861/6553 is trying to acquire lock: ffff0000d3cc5908 (&ptp->n_vclocks_mux){+.+.}-{3:3}, at: ptp_vclock_in_use drivers/ptp/ptp_private.h:104 [inline] ffff0000d3cc5908 (&ptp->n_vclocks_mux){+.+.}-{3:3}, at: ptp_clock_freerun drivers/ptp/ptp_private.h:121 [inline] ffff0000d3cc5908 (&ptp->n_vclocks_mux){+.+.}-{3:3}, at: ptp_clock_settime+0x174/0x278 drivers/ptp/ptp_clock.c:81 but task is already holding lock: ffff0000d3cc4130 (&clk->rwsem){++++}-{3:3}, at: get_posix_clock kernel/time/posix-clock.c:25 [inline] ffff0000d3cc4130 (&clk->rwsem){++++}-{3:3}, at: get_clock_desc kernel/time/posix-clock.c:232 [inline] ffff0000d3cc4130 (&clk->rwsem){++++}-{3:3}, at: pc_clock_settime+0x17c/0x294 kernel/time/posix-clock.c:317 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&clk->rwsem){++++}-{3:3}: down_write+0x5c/0x88 kernel/locking/rwsem.c:1573 posix_clock_unregister+0x50/0xb8 kernel/time/posix-clock.c:207 ptp_clock_unregister+0x190/0x1f0 drivers/ptp/ptp_clock.c:391 ptp_vclock_unregister+0x100/0x130 drivers/ptp/ptp_vclock.c:230 unregister_vclock+0xdc/0x14c drivers/ptp/ptp_sysfs.c:164 device_for_each_child_reverse+0x110/0x1a8 drivers/base/core.c:4073 n_vclocks_store+0x1ec/0x650 drivers/ptp/ptp_sysfs.c:228 dev_attr_store+0x6c/0x90 drivers/base/core.c:2388 sysfs_kf_write+0x1f8/0x274 fs/sysfs/file.c:140 kernfs_fop_write_iter+0x390/0x4b4 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+0x3c8/0x7c8 fs/read_write.c:584 ksys_write+0x12c/0x228 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:646 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #0 (&ptp->n_vclocks_mux){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3162 [inline] check_prevs_add kernel/locking/lockdep.c:3281 [inline] validate_chain kernel/locking/lockdep.c:3897 [inline] __lock_acquire+0x3504/0x7280 kernel/locking/lockdep.c:5171 lock_acquire+0x210/0x63c kernel/locking/lockdep.c:5790 __mutex_lock_common+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_interruptible_nested+0x38/0x44 kernel/locking/mutex.c:821 ptp_vclock_in_use drivers/ptp/ptp_private.h:104 [inline] ptp_clock_freerun drivers/ptp/ptp_private.h:121 [inline] ptp_clock_settime+0x174/0x278 drivers/ptp/ptp_clock.c:81 pc_clock_settime+0x220/0x294 kernel/time/posix-clock.c:327 __do_sys_clock_settime kernel/time/posix-timers.c:1125 [inline] __se_sys_clock_settime kernel/time/posix-timers.c:1113 [inline] __arm64_sys_clock_settime+0x208/0x25c kernel/time/posix-timers.c:1113 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x200/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&clk->rwsem); lock(&ptp->n_vclocks_mux); lock(&clk->rwsem); lock(&ptp->n_vclocks_mux); *** DEADLOCK *** 1 lock held by syz.1.861/6553: #0: ffff0000d3cc4130 (&clk->rwsem){++++}-{3:3}, at: get_posix_clock kernel/time/posix-clock.c:25 [inline] #0: ffff0000d3cc4130 (&clk->rwsem){++++}-{3:3}, at: get_clock_desc kernel/time/posix-clock.c:232 [inline] #0: ffff0000d3cc4130 (&clk->rwsem){++++}-{3:3}, at: pc_clock_settime+0x17c/0x294 kernel/time/posix-clock.c:317 stack backtrace: CPU: 1 PID: 6553 Comm: syz.1.861 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2088 check_noncircular+0x290/0x370 kernel/locking/lockdep.c:2215 check_prev_add kernel/locking/lockdep.c:3162 [inline] check_prevs_add kernel/locking/lockdep.c:3281 [inline] validate_chain kernel/locking/lockdep.c:3897 [inline] __lock_acquire+0x3504/0x7280 kernel/locking/lockdep.c:5171 lock_acquire+0x210/0x63c kernel/locking/lockdep.c:5790 __mutex_lock_common+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_interruptible_nested+0x38/0x44 kernel/locking/mutex.c:821 ptp_vclock_in_use drivers/ptp/ptp_private.h:104 [inline] ptp_clock_freerun drivers/ptp/ptp_private.h:121 [inline] ptp_clock_settime+0x174/0x278 drivers/ptp/ptp_clock.c:81 pc_clock_settime+0x220/0x294 kernel/time/posix-clock.c:327 __do_sys_clock_settime kernel/time/posix-timers.c:1125 [inline] __se_sys_clock_settime kernel/time/posix-timers.c:1113 [inline] __arm64_sys_clock_settime+0x208/0x25c kernel/time/posix-timers.c:1113 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x200/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585