6f7ac82853
As virtual_context_destroy() may be called from a request signal, it may be called from inside an irq-off section, and so we need to do a full save/restore of the irq state rather than blindly re-enable irqs upon unlocking. <4> [110.024262] WARNING: inconsistent lock state <4> [110.024277] 5.4.0-rc8-CI-CI_DRM_7489+ #1 Tainted: G U <4> [110.024292] -------------------------------- <4> [110.024305] inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage. <4> [110.024323] kworker/0:0/5 [HC0[0]:SC0[0]:HE1:SE1] takes: <4> [110.024338] ffff88826a0c7a18 (&(&rq->lock)->rlock){?.-.}, at: i915_request_retire+0x221/0x930 [i915] <4> [110.024592] {IN-HARDIRQ-W} state was registered at: <4> [110.024612] lock_acquire+0xa7/0x1c0 <4> [110.024627] _raw_spin_lock_irqsave+0x33/0x50 <4> [110.024788] intel_engine_breadcrumbs_irq+0x38c/0x600 [i915] <4> [110.024808] irq_work_run_list+0x49/0x70 <4> [110.024824] irq_work_run+0x26/0x50 <4> [110.024839] smp_irq_work_interrupt+0x44/0x1e0 <4> [110.024855] irq_work_interrupt+0xf/0x20 <4> [110.024871] __do_softirq+0xb7/0x47f <4> [110.024885] irq_exit+0xba/0xc0 <4> [110.024898] do_IRQ+0x83/0x160 <4> [110.024910] ret_from_intr+0x0/0x1d <4> [110.024922] irq event stamp: 172864 <4> [110.024938] hardirqs last enabled at (172863): [<ffffffff819ea214>] _raw_spin_unlock_irq+0x24/0x50 <4> [110.024963] hardirqs last disabled at (172864): [<ffffffff819e9fba>] _raw_spin_lock_irq+0xa/0x40 <4> [110.024988] softirqs last enabled at (172812): [<ffffffff81c00385>] __do_softirq+0x385/0x47f <4> [110.025012] softirqs last disabled at (172797): [<ffffffff810b829a>] irq_exit+0xba/0xc0 <4> [110.025031] other info that might help us debug this: <4> [110.025049] Possible unsafe locking scenario: <4> [110.025065] CPU0 <4> [110.025075] ---- <4> [110.025084] lock(&(&rq->lock)->rlock); <4> [110.025099] <Interrupt> <4> [110.025109] lock(&(&rq->lock)->rlock); <4> [110.025124] *** DEADLOCK *** <4> [110.025144] 4 locks held by kworker/0:0/5: <4> [110.025156] #0: ffff88827588f528 ((wq_completion)events){+.+.}, at: process_one_work+0x1de/0x620 <4> [110.025187] #1: ffffc9000006fe78 ((work_completion)(&engine->retire_work)){+.+.}, at: process_one_work+0x1de/0x620 <4> [110.025219] #2: ffff88825605e270 (&kernel#2){+.+.}, at: engine_retire+0x57/0xe0 [i915] <4> [110.025405] #3: ffff88826a0c7a18 (&(&rq->lock)->rlock){?.-.}, at: i915_request_retire+0x221/0x930 [i915] <4> [110.025634] stack backtrace: <4> [110.025653] CPU: 0 PID: 5 Comm: kworker/0:0 Tainted: G U 5.4.0-rc8-CI-CI_DRM_7489+ #1 <4> [110.025675] Hardware name: /NUC7i5BNB, BIOS BNKBL357.86A.0054.2017.1025.1822 10/25/2017 <4> [110.025856] Workqueue: events engine_retire [i915] <4> [110.025872] Call Trace: <4> [110.025891] dump_stack+0x71/0x9b <4> [110.025907] mark_lock+0x49a/0x500 <4> [110.025926] ? print_shortest_lock_dependencies+0x200/0x200 <4> [110.025946] mark_held_locks+0x49/0x70 <4> [110.025962] ? _raw_spin_unlock_irq+0x24/0x50 <4> [110.025978] lockdep_hardirqs_on+0xa2/0x1c0 <4> [110.025995] _raw_spin_unlock_irq+0x24/0x50 <4> [110.026171] virtual_context_destroy+0xc5/0x2e0 [i915] <4> [110.026376] __active_retire+0xb4/0x290 [i915] <4> [110.026396] dma_fence_signal_locked+0x9e/0x1b0 <4> [110.026613] i915_request_retire+0x451/0x930 [i915] <4> [110.026766] retire_requests+0x4d/0x60 [i915] <4> [110.026919] engine_retire+0x63/0xe0 [i915] Fixes: b1e3177bd1d8 ("drm/i915: Coordinate i915_active with its own mutex") Fixes: 6d06779e8672 ("drm/i915: Load balancing across a virtual engine") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20191205145934.663183-1-chris@chris-wilson.co.uk
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.