Am 11.08.20 um 09:36 schrieb Chen, Guchun:
[AMD Public Use]- down_write(&adev->reset_sem); + if (hive) { + down_write_nest_lock(&adev->reset_sem, &hive->hive_lock); + } else + down_write(&adev->reset_sem);Coding style nit pick: You should drop the {} here. {} could not be dropped here, as down_write_nest_lock Is one macro with multiple lines, otherwise, build error would say 'else' missed one previous 'if'. Instead of dropping, another {} should be added to else to include down_write(&adev->reset_sem), which makes the braces been balanced.
Interesting bug, that is something which should not happen with macros in the Linux kernel. They protection by "do { ... } while(0)" is mandatory here.
Let me take a look, Christian.
Regards, Guchun -----Original Message----- From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Christian König Sent: Tuesday, August 11, 2020 2:53 PM To: Li, Dennis <Dennis.Li@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Kuehling, Felix <Felix.Kuehling@xxxxxxx>; Zhang, Hawking <Hawking.Zhang@xxxxxxx>; daniel@xxxxxxxx Subject: Re: [PATCH v3] drm/amdgpu: annotate a false positive recursive locking Am 11.08.20 um 04:12 schrieb Dennis Li:[ 584.110304] ============================================ [ 584.110590] WARNING: possible recursive locking detected [ 584.110876] 5.6.0-deli-v5.6-2848-g3f3109b0e75f #1 Tainted: G OE [ 584.111164] -------------------------------------------- [ 584.111456] kworker/38:1/553 is trying to acquire lock: [ 584.111721] ffff9b15ff0a47a0 (&adev->reset_sem){++++}, at: amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.112112] but task is already holding lock: [ 584.112673] ffff9b1603d247a0 (&adev->reset_sem){++++}, at: amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.113068] other info that might help us debug this: [ 584.113689] Possible unsafe locking scenario: [ 584.114350] CPU0 [ 584.114685] ---- [ 584.115014] lock(&adev->reset_sem); [ 584.115349] lock(&adev->reset_sem); [ 584.115678] *** DEADLOCK *** [ 584.116624] May be due to missing lock nesting notation [ 584.117284] 4 locks held by kworker/38:1/553: [ 584.117616] #0: ffff9ad635c1d348 ((wq_completion)events){+.+.}, at: process_one_work+0x21f/0x630 [ 584.117967] #1: ffffac708e1c3e58 ((work_completion)(&con->recovery_work)){+.+.}, at: process_one_work+0x21f/0x630 [ 584.118358] #2: ffffffffc1c2a5d0 (&tmp->hive_lock){+.+.}, at: amdgpu_device_gpu_recover+0xae/0x1030 [amdgpu] [ 584.118786] #3: ffff9b1603d247a0 (&adev->reset_sem){++++}, at: amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.119222] stack backtrace: [ 584.119990] CPU: 38 PID: 553 Comm: kworker/38:1 Kdump: loaded Tainted: G OE 5.6.0-deli-v5.6-2848-g3f3109b0e75f #1 [ 584.120782] Hardware name: Supermicro SYS-7049GP-TRT/X11DPG-QT, BIOS 3.1 05/23/2019 [ 584.121223] Workqueue: events amdgpu_ras_do_recovery [amdgpu] [ 584.121638] Call Trace: [ 584.122050] dump_stack+0x98/0xd5 [ 584.122499] __lock_acquire+0x1139/0x16e0 [ 584.122931] ? trace_hardirqs_on+0x3b/0xf0 [ 584.123358] ? cancel_delayed_work+0xa6/0xc0 [ 584.123771] lock_acquire+0xb8/0x1c0 [ 584.124197] ? amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.124599] down_write+0x49/0x120 [ 584.125032] ? amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.125472] amdgpu_device_gpu_recover+0x262/0x1030 [amdgpu] [ 584.125910] ? amdgpu_ras_error_query+0x1b8/0x2a0 [amdgpu] [ 584.126367] amdgpu_ras_do_recovery+0x159/0x190 [amdgpu] [ 584.126789] process_one_work+0x29e/0x630 [ 584.127208] worker_thread+0x3c/0x3f0 [ 584.127621] ? __kthread_parkme+0x61/0x90 [ 584.128014] kthread+0x12f/0x150 [ 584.128402] ? process_one_work+0x630/0x630 [ 584.128790] ? kthread_park+0x90/0x90 [ 584.129174] ret_from_fork+0x3a/0x50 Each adev has owned lock_class_key to avoid false positive recursive locking. v2: 1. register adev->lock_key into lockdep, otherwise lockdep will report the below warning [ 1216.705820] BUG: key ffff890183b647d0 has not been registered! [ 1216.705924] ------------[ cut here ]------------ [ 1216.705972] DEBUG_LOCKS_WARN_ON(1) [ 1216.705997] WARNING: CPU: 20 PID: 541 at kernel/locking/lockdep.c:3743 lockdep_init_map+0x150/0x210 v3: change to use down_write_nest_lock to annotate the false dead-lock warning. Signed-off-by: Dennis Li <Dennis.Li@xxxxxxx> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c index 62ecac97fbd2..8a55b0bc044a 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c @@ -4145,12 +4145,15 @@ static int amdgpu_do_asic_reset(struct amdgpu_hive_info *hive, return r; }-static bool amdgpu_device_lock_adev(struct amdgpu_device *adev)+static bool amdgpu_device_lock_adev(struct amdgpu_device *adev, +struct amdgpu_hive_info *hive) { if (atomic_cmpxchg(&adev->in_gpu_reset, 0, 1) != 0) return false;- down_write(&adev->reset_sem);+ if (hive) { + down_write_nest_lock(&adev->reset_sem, &hive->hive_lock); + } else + down_write(&adev->reset_sem);Coding style nit pick: You should drop the {} here. Apart from that the patch is Reviewed-by: Christian König <christian.koenig@xxxxxxx>atomic_inc(&adev->gpu_reset_counter);switch (amdgpu_asic_reset_method(adev)) { @@ -4312,7 +4315,7 @@ int amdgpu_device_gpu_recover(struct amdgpu_device *adev,/* block all schedulers and reset given job's ring */list_for_each_entry(tmp_adev, device_list_handle, gmc.xgmi.head) { - if (!amdgpu_device_lock_adev(tmp_adev)) { + if (!amdgpu_device_lock_adev(tmp_adev, hive)) { DRM_INFO("Bailing on TDR for s_job:%llx, as another already in progress", job ? job->base.id : -1); r = 0;_______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Famd-gfx&data=02%7C01%7Cguchun.chen%40amd.com%7C0a3fd06c0e774002a0e908d83dc337a0%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637327255952065510&sdata=rJ%2BbWsWJ6NfPUinwUHxnRfVxYi%2Ft4JQCTtamMATrLws%3D&reserved=0
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