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Date: Sat, 4 May 2024 04:39:57 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>, Alex Constantino
<dreaming.about.electric.sheep@...il.com>, Maxime Ripard
<mripard@...nel.org>, Timo Lindfors <timo.lindfors@....fi>, Dave Airlie
<airlied@...hat.com>, Gerd Hoffmann <kraxel@...hat.com>, Maarten Lankhorst
<maarten.lankhorst@...ux.intel.com>, Thomas Zimmermann
<tzimmermann@...e.de>, Daniel Vetter <daniel@...ll.ch>
Subject: Re: [BUG][v6.9-rc6] Deadlock with: Revert "drm/qxl: simplify
qxl_fence_wait"
Did anyone see this?
-- Steve
On Thu, 2 May 2024 08:16:41 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:
> I went to run my tests on my VMs and the tests hung on boot up.
> Unfortunately, the most I ever got out was:
>
> [ 93.607888] Testing event system initcall: OK
> [ 93.667730] Running tests on all trace events:
> [ 93.669757] Testing all events: OK
> [ 95.631064] ------------[ cut here ]------------
> Timed out after 60 seconds
>
> I ran a bisect and it came up with:
>
> # first bad commit: [07ed11afb68d94eadd4ffc082b97c2331307c5ea] Revert "drm/qxl: simplify qxl_fence_wait"
>
> I checked out 07ed11afb68d94eadd4ffc082b97c2331307c5ea~1 and it booted
> fine. Added back that commit, it failed to boot. I did this twice, and got
> the same results.
>
> But the last time I ran it, it did trigger this:
>
> ------------[ cut here ]------------
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.9.0-rc1-test-00021-g07ed11afb68d #5 Not tainted
> ------------------------------------------------------
> kworker/u24:3/119 is trying to acquire lock:
> ffffffff95aa4600 (console_owner){....}-{0:0}, at: console_flush_all+0x1f5/0x530
>
> but task is already holding lock:
> ffff93c4bbd37218 (&pool->lock){-.-.}-{2:2}, at: __flush_work+0xc1/0x440
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #1 (&pool->lock){-.-.}-{2:2}:
> _raw_spin_lock+0x33/0x40
> __queue_work+0xd6/0x610
> queue_work_on+0x8a/0x90
> soft_cursor+0x1a0/0x230
> bit_cursor+0x386/0x5f0
> hide_cursor+0x27/0xb0
> vt_console_print+0x474/0x490
> console_flush_all+0x22e/0x530
> console_unlock+0x56/0x160
> vprintk_emit+0x160/0x390
> dev_printk_emit+0xa5/0xd0
> _dev_info+0x79/0xa0
> __drm_fb_helper_initial_config_and_unlock+0x3a9/0x5f0
> drm_fbdev_generic_client_hotplug+0x69/0xc0
> drm_client_register+0x7b/0xc0
> qxl_pci_probe+0x107/0x1a0
> local_pci_probe+0x45/0xa0
> pci_device_probe+0xc7/0x240
> really_probe+0xd6/0x390
> __driver_probe_device+0x78/0x150
> driver_probe_device+0x1f/0x90
> __driver_attach+0xd6/0x1d0
> bus_for_each_dev+0x8f/0xe0
> bus_add_driver+0x119/0x220
> driver_register+0x59/0x100
> do_one_initcall+0x76/0x3c0
> kernel_init_freeable+0x3a5/0x5b0
> kernel_init+0x1a/0x1c0
> ret_from_fork+0x34/0x50
> ret_from_fork_asm+0x1a/0x30
>
> -> #0 (console_owner){....}-{0:0}:
> __lock_acquire+0x13e7/0x2180
> lock_acquire+0xd9/0x300
> console_flush_all+0x212/0x530
> console_unlock+0x56/0x160
> vprintk_emit+0x160/0x390
> _printk+0x64/0x80
> __warn_printk+0x8e/0x180
> check_flush_dependency+0xfd/0x120
> __flush_work+0xfa/0x440
> qxl_queue_garbage_collect+0x83/0x90
> qxl_fence_wait+0xa4/0x1a0
> dma_fence_wait_timeout+0x98/0x1e0
> dma_resv_wait_timeout+0x7f/0xe0
> ttm_bo_delayed_delete+0x2b/0x90
> process_one_work+0x228/0x740
> worker_thread+0x1dc/0x3c0
> kthread+0xf2/0x120
> ret_from_fork+0x34/0x50
> ret_from_fork_asm+0x1a/0x30
>
> other info that might help us debug this:
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(&pool->lock);
> lock(console_owner);
> lock(&pool->lock);
> lock(console_owner);
>
> *** DEADLOCK ***
>
> 6 locks held by kworker/u24:3/119:
> #0: ffff93c440245948 ((wq_completion)ttm){+.+.}-{0:0}, at: process_one_work+0x43a/0x740
> #1: ffffa01380d83e60 ((work_completion)(&bo->delayed_delete)){+.+.}-{0:0}, at: process_one_work+0x1e2/0x740
> #2: ffffffff95b17880 (rcu_read_lock){....}-{1:2}, at: __flush_work+0x86/0x440
> #3: ffff93c4bbd37218 (&pool->lock){-.-.}-{2:2}, at: __flush_work+0xc1/0x440
> #4: ffffffff95b149c0 (console_lock){+.+.}-{0:0}, at: _printk+0x64/0x80
> #5: ffffffff95b14a10 (console_srcu){....}-{0:0}, at: console_flush_all+0x7b/0x530
>
> stack backtrace:
> CPU: 2 PID: 119 Comm: kworker/u24:3 Not tainted 6.9.0-rc1-test-00021-g07ed11afb68d #5
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
> Workqueue: ttm ttm_bo_delayed_delete
> Call Trace:
> <TASK>
> dump_stack_lvl+0x77/0xb0
> check_noncircular+0x148/0x160
> __lock_acquire+0x13e7/0x2180
> lock_acquire+0xd9/0x300
> ? console_flush_all+0x1f5/0x530
> ? lock_release+0x147/0x2c0
> ? console_flush_all+0x1f5/0x530
> console_flush_all+0x212/0x530
> ? console_flush_all+0x1f5/0x530
> console_unlock+0x56/0x160
> vprintk_emit+0x160/0x390
> _printk+0x64/0x80
> ? __pfx_ttm_bo_delayed_delete+0x10/0x10
> ? __pfx_qxl_gc_work+0x10/0x10
> __warn_printk+0x8e/0x180
> ? __pfx_ttm_bo_delayed_delete+0x10/0x10
> ? __pfx_qxl_gc_work+0x10/0x10
> ? __pfx_qxl_gc_work+0x10/0x10
> check_flush_dependency+0xfd/0x120
> __flush_work+0xfa/0x440
> qxl_queue_garbage_collect+0x83/0x90
> qxl_fence_wait+0xa4/0x1a0
> dma_fence_wait_timeout+0x98/0x1e0
> dma_resv_wait_timeout+0x7f/0xe0
> ttm_bo_delayed_delete+0x2b/0x90
> process_one_work+0x228/0x740
> worker_thread+0x1dc/0x3c0
> ? __pfx_worker_thread+0x10/0x10
> kthread+0xf2/0x120
> ? __pfx_kthread+0x10/0x10
> ret_from_fork+0x34/0x50
> ? __pfx_kthread+0x10/0x10
> ret_from_fork_asm+0x1a/0x30
> </TASK>
> workqueue: WQ_MEM_RECLAIM ttm:ttm_bo_delayed_delete is flushing !WQ_MEM_RECLAIM events:qxl_gc_work
> WARNING: CPU: 2 PID: 119 at kernel/workqueue.c:3728 check_flush_dependency+0xfd/0x120
> Modules linked in:
> CPU: 2 PID: 119 Comm: kworker/u24:3 Not tainted 6.9.0-rc1-test-00021-g07ed11afb68d #5
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
> Workqueue: ttm ttm_bo_delayed_delete
> RIP: 0010:check_flush_dependency+0xfd/0x120
> Code: 8b 45 18 48 8d b2 70 01 00 00 49 89 e8 48 8d 8b 70 01 00 00 48 c7 c7 60 46 7b 95 c6 05 48 67 d2 01 01 48 89 c2 e8 63 40 fd ff <0f> 0b e9 1e ff ff ff 80 3d 33 67 d2 01 00 75 93 e9 4a ff ff ff 66
> RSP: 0000:ffffa01380d83c28 EFLAGS: 00010086
> RAX: 0000000000000000 RBX: ffff93c44004ee00 RCX: 0000000000000000
> RDX: 0000000080000003 RSI: 00000000ffffefff RDI: 0000000000000001
> RBP: ffffffff9497b100 R08: 0000000000000000 R09: 0000000000000003
> R10: ffffa01380d83ab8 R11: ffffffff95b14828 R12: ffff93c443980000
> R13: ffff93c440fbe300 R14: 0000000000000001 R15: ffff93c44004ee00
> FS: 0000000000000000(0000) GS:ffff93c4bbd00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 000000007c864001 CR4: 0000000000170ef0
> Call Trace:
> <TASK>
> ? __warn+0x8c/0x180
> ? check_flush_dependency+0xfd/0x120
> ? report_bug+0x191/0x1c0
> ? prb_read_valid+0x1b/0x30
> ? handle_bug+0x3c/0x80
> ? exc_invalid_op+0x17/0x70
> ? asm_exc_invalid_op+0x1a/0x20
> ? __pfx_qxl_gc_work+0x10/0x10
> ? check_flush_dependency+0xfd/0x120
> ? check_flush_dependency+0xfd/0x120
> __flush_work+0xfa/0x440
> qxl_queue_garbage_collect+0x83/0x90
> qxl_fence_wait+0xa4/0x1a0
> dma_fence_wait_timeout+0x98/0x1e0
> dma_resv_wait_timeout+0x7f/0xe0
> ttm_bo_delayed_delete+0x2b/0x90
> process_one_work+0x228/0x740
> worker_thread+0x1dc/0x3c0
> ? __pfx_worker_thread+0x10/0x10
> kthread+0xf2/0x120
> ? __pfx_kthread+0x10/0x10
> ret_from_fork+0x34/0x50
> ? __pfx_kthread+0x10/0x10
> ret_from_fork_asm+0x1a/0x30
> </TASK>
> irq event stamp: 58
> hardirqs last enabled at (57): [<ffffffff93fede30>] queue_work_on+0x60/0x90
> hardirqs last disabled at (58): [<ffffffff94ea7f66>] _raw_spin_lock_irq+0x56/0x60
> softirqs last enabled at (0): [<ffffffff93fbae27>] copy_process+0xc07/0x2c60
> softirqs last disabled at (0): [<0000000000000000>] 0x0
> ---[ end trace 0000000000000000 ]---
>
> So there's an issue with dma_fence and a workqueue.
>
> -- Steve
>
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