On 2018-11-22 17:04:19 [+0800], zhe.he@xxxxxxxxxxxxx wrote: > From: He Zhe <zhe.he@xxxxxxxxxxxxx> > > kmemleak_lock, as a rwlock on RT, can possibly be held in atomic context and > causes the follow BUG. > > BUG: scheduling while atomic: migration/15/132/0x00000002 … > Preemption disabled at: > [<ffffffff8c927c11>] cpu_stopper_thread+0x71/0x100 > CPU: 15 PID: 132 Comm: migration/15 Not tainted 4.19.0-rt1-preempt-rt #1 > Hardware name: Intel Corp. Harcuvar/Server, BIOS HAVLCRB1.X64.0015.D62.1708310404 08/31/2017 > Call Trace: > dump_stack+0x4f/0x6a > ? cpu_stopper_thread+0x71/0x100 > __schedule_bug.cold.16+0x38/0x55 > __schedule+0x484/0x6c0 > schedule+0x3d/0xe0 > rt_spin_lock_slowlock_locked+0x118/0x2a0 > rt_spin_lock_slowlock+0x57/0x90 > __rt_spin_lock+0x26/0x30 > __write_rt_lock+0x23/0x1a0 > ? intel_pmu_cpu_dying+0x67/0x70 > rt_write_lock+0x2a/0x30 > find_and_remove_object+0x1e/0x80 > delete_object_full+0x10/0x20 > kmemleak_free+0x32/0x50 > kfree+0x104/0x1f0 > ? x86_pmu_starting_cpu+0x30/0x30 > intel_pmu_cpu_dying+0x67/0x70 > x86_pmu_dying_cpu+0x1a/0x30 > cpuhp_invoke_callback+0x92/0x700 > take_cpu_down+0x70/0xa0 > multi_cpu_stop+0x62/0xc0 > ? cpu_stop_queue_work+0x130/0x130 > cpu_stopper_thread+0x79/0x100 > smpboot_thread_fn+0x20f/0x2d0 > kthread+0x121/0x140 > ? sort_range+0x30/0x30 > ? kthread_park+0x90/0x90 > ret_from_fork+0x35/0x40 If this is the only problem? kfree() from a preempt-disabled section should cause a warning even without kmemleak. > And on v4.18 stable tree the following call trace, caused by grabbing > kmemleak_lock again, is also observed. > > kernel BUG at kernel/locking/rtmutex.c:1048! > invalid opcode: 0000 [#1] PREEMPT SMP PTI > CPU: 5 PID: 689 Comm: mkfs.ext4 Not tainted 4.18.16-rt9-preempt-rt #1 … > Call Trace: > ? preempt_count_add+0x74/0xc0 > rt_spin_lock_slowlock+0x57/0x90 > ? __kernel_text_address+0x12/0x40 > ? __save_stack_trace+0x75/0x100 > __rt_spin_lock+0x26/0x30 > __write_rt_lock+0x23/0x1a0 > rt_write_lock+0x2a/0x30 > create_object+0x17d/0x2b0 … is this an RT-only problem? Because mainline should not allow read->read locking or read->write locking for reader-writer locks. If this only happens on v4.18 and not on v4.19 then something must have fixed it. Sebastian
