f8db4d051b
With deferring the breadcrumb signalling to the virtual engine (thanks preempt-to-busy) we need to make sure the lists and irq-worker are ready to send a signal. [41958.710544] BUG: kernel NULL pointer dereference, address: 0000000000000000 [41958.710553] #PF: supervisor write access in kernel mode [41958.710556] #PF: error_code(0x0002) - not-present page [41958.710558] PGD 0 P4D 0 [41958.710562] Oops: 0002 [#1] SMP [41958.710565] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G U 5.3.0+ #207 [41958.710568] Hardware name: Intel Corporation NUC7i5BNK/NUC7i5BNB, BIOS BNKBL357.86A.0052.2017.0918.1346 09/18/2017 [41958.710602] RIP: 0010:i915_request_enable_breadcrumb+0xe1/0x130 [i915] [41958.710605] Code: 8b 44 24 30 48 89 41 08 48 89 08 48 8b 85 98 01 00 00 48 8d 8d 90 01 00 00 48 89 95 98 01 00 00 49 89 4c 24 28 49 89 44 24 30 <48> 89 10 f0 80 4b 30 10 c6 85 88 01 00 00 00 e9 1a ff ff ff 48 83 [41958.710609] RSP: 0018:ffffc90000003de0 EFLAGS: 00010046 [41958.710612] RAX: 0000000000000000 RBX: ffff888735424480 RCX: ffff8887cddb2190 [41958.710614] RDX: ffff8887cddb3570 RSI: ffff888850362190 RDI: ffff8887cddb2188 [41958.710617] RBP: ffff8887cddb2000 R08: ffff8888503624a8 R09: 0000000000000100 [41958.710619] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8887cddb3548 [41958.710622] R13: 0000000000000000 R14: 0000000000000046 R15: ffff888850362070 [41958.710625] FS: 0000000000000000(0000) GS:ffff88885ea00000(0000) knlGS:0000000000000000 [41958.710628] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [41958.710630] CR2: 0000000000000000 CR3: 0000000002c09002 CR4: 00000000001606f0 [41958.710633] Call Trace: [41958.710636] <IRQ> [41958.710668] __i915_request_submit+0x12b/0x160 [i915] [41958.710693] virtual_submit_request+0x67/0x120 [i915] [41958.710720] __unwind_incomplete_requests+0x131/0x170 [i915] [41958.710744] execlists_dequeue+0xb40/0xe00 [i915] [41958.710771] execlists_submission_tasklet+0x10f/0x150 [i915] [41958.710776] tasklet_action_common.isra.17+0x41/0xa0 [41958.710781] __do_softirq+0xc8/0x221 [41958.710785] irq_exit+0xa6/0xb0 [41958.710788] smp_apic_timer_interrupt+0x4d/0x80 [41958.710791] apic_timer_interrupt+0xf/0x20 [41958.710794] </IRQ> Fixes: cb2377a919bb ("drm/i915: Fixup preempt-to-busy vs reset of a virtual request") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20191001103518.9113-1-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.