Re: [PATCH 2/7] drm: add syncobj timeline support v8

From: Chris Wilson <chris-Y6uKTt2uX1cEflXRtASbqLVCufUGDwFn@public.gmane.org>
To: Chunming Zhou <david1.zhou-5C7GfCeVMHo@public.gmane.org>,
	dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
Cc: Dave Airlie <airlied-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Daniel Rakos <Daniel.Rakos-5C7GfCeVMHo@public.gmane.org>,
	Christian Konig <christian.koenig-5C7GfCeVMHo@public.gmane.org>,
	amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
Subject: Re: [PATCH 2/7] drm: add syncobj timeline support v8
Date: Fri, 19 Oct 2018 09:49:02 +0100	[thread overview]
Message-ID: <153993893770.19935.6989551886574520401@skylake-alporthouse-com> (raw)
In-Reply-To: <20181015085553.30656-2-david1.zhou-5C7GfCeVMHo@public.gmane.org>

Quoting Chunming Zhou (2018-10-15 09:55:48)
> This patch is for VK_KHR_timeline_semaphore extension, semaphore is called syncobj in kernel side:
> This extension introduces a new type of syncobj that has an integer payload
> identifying a point in a timeline. Such timeline syncobjs support the
> following operations:
>    * CPU query - A host operation that allows querying the payload of the
>      timeline syncobj.
>    * CPU wait - A host operation that allows a blocking wait for a
>      timeline syncobj to reach a specified value.
>    * Device wait - A device operation that allows waiting for a
>      timeline syncobj to reach a specified value.
>    * Device signal - A device operation that allows advancing the
>      timeline syncobj to a specified value.

Spinlock recursion:

https://bugs.freedesktop.org/show_bug.cgi?id=108490
<6> [363.585915] [IGT] syncobj_wait: executing
<6> [363.646916] [IGT] syncobj_wait: starting subtest wait-for-submit-delayed-submit
<4> [363.752517]
<4> [363.752542] ============================================
<4> [363.752561] WARNING: possible recursive locking detected
<4> [363.752582] 4.19.0-rc8-CI-CI_DRM_5006+ #1 Tainted: G U
<4> [363.752602] --------------------------------------------
<4> [363.752621] syncobj_wait/2297 is trying to acquire lock:
<4> [363.752641] 0000000029228054 (&(&syncobj->lock)->rlock){+.+.}, at: drm_syncobj_garbage_collection+0x25/0x140
<4> [363.752699] \x0abut task is already holding lock:
<4> [363.752721] 0000000029228054 (&(&syncobj->lock)->rlock){+.+.}, at: drm_syncobj_replace_fence+0x1b6/0x2c0
<4> [363.752768] \x0aother info that might help us debug this:
<4> [363.752791] Possible unsafe locking scenario:\x0a
<4> [363.752812] CPU0
<4> [363.752824] ----
<4> [363.752835] lock(&(&syncobj->lock)->rlock);
<4> [363.752856] lock(&(&syncobj->lock)->rlock);
<4> [363.752877] \x0a *** DEADLOCK ***\x0a
<4> [363.752905] May be due to missing lock nesting notation\x0a
<4> [363.752932] 1 lock held by syncobj_wait/2297:
<4> [363.752949] #0: 0000000029228054 (&(&syncobj->lock)->rlock){+.+.}, at: drm_syncobj_replace_fence+0x1b6/0x2c0
<4> [363.753001] \x0astack backtrace:
<4> [363.753030] CPU: 2 PID: 2297 Comm: syncobj_wait Tainted: G U 4.19.0-rc8-CI-CI_DRM_5006+ #1
<4> [363.753060] Hardware name: Google Caroline/Caroline, BIOS MrChromebox 08/27/2018
<4> [363.753083] Call Trace:
<4> [363.753109] dump_stack+0x67/0x9b
<4> [363.753136] __lock_acquire+0xc67/0x1b50
<4> [363.753164] ? deactivate_slab.isra.26+0x7a4/0x7e0
<4> [363.753203] ? __lock_acquire+0x3c8/0x1b50
<4> [363.753242] ? __wake_up_common_lock+0x5e/0xb0
<4> [363.753285] ? lock_acquire+0xa6/0x1c0
<4> [363.753306] lock_acquire+0xa6/0x1c0
<4> [363.753334] ? drm_syncobj_garbage_collection+0x25/0x140
<4> [363.753365] _raw_spin_lock+0x2a/0x40
<4> [363.753392] ? drm_syncobj_garbage_collection+0x25/0x140
<4> [363.753419] drm_syncobj_garbage_collection+0x25/0x140
<4> [363.753450] drm_syncobj_search_fence+0x38/0x200
<4> [363.753478] ? drm_syncobj_replace_fence+0x1b6/0x2c0
<4> [363.753509] syncobj_wait_syncobj_func+0x11/0x20
<4> [363.753536] drm_syncobj_replace_fence+0x1f8/0x2c0
<4> [363.753561] ? drm_syncobj_handle_to_fd_ioctl+0x170/0x170
<4> [363.753585] drm_syncobj_fd_to_handle_ioctl+0x120/0x1d0
<4> [363.753609] ? drm_syncobj_handle_to_fd_ioctl+0x170/0x170
<4> [363.753638] drm_ioctl_kernel+0x81/0xf0
<4> [363.753665] drm_ioctl+0x2e6/0x3a0
<4> [363.753686] ? drm_syncobj_handle_to_fd_ioctl+0x170/0x170
<4> [363.753717] ? lock_acquire+0xa6/0x1c0
<4> [363.753743] do_vfs_ioctl+0xa0/0x6d0
<4> [363.753769] ? __fget+0xfc/0x1e0
<4> [363.753792] ksys_ioctl+0x35/0x60
<4> [363.753816] __x64_sys_ioctl+0x11/0x20
<4> [363.753840] do_syscall_64+0x55/0x190
<4> [363.753866] entry_SYSCALL_64_after_hwframe+0x49/0xbe
<4> [363.753890] RIP: 0033:0x7f0d84f9a5d7
<4> [363.753911] Code: b3 66 90 48 8b 05 b1 48 2d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 81 48 2d 00 f7 d8 64 89 01 48
<4> [363.753959] RSP: 002b:00007f0d79804ac8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
<4> [363.753990] RAX: ffffffffffffffda RBX: 00007f0d74000b20 RCX: 00007f0d84f9a5d7
<4> [363.754016] RDX: 00007f0d79804b50 RSI: 00000000c01064c2 RDI: 0000000000000005
<4> [363.754040] RBP: 00007f0d79804b50 R08: 0000000000000000 R09: 000000000000001e
<4> [363.754064] R10: 0000000000000054 R11: 0000000000000246 R12: 00000000c01064c2
<4> [363.754088] R13: 0000000000000005 R14: 00007f0d74000b20 R15: 000055ab44e2c3f8
-Chris
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