Commit f691eaa4 authored by Chris Wilson's avatar Chris Wilson Committed by Jani Nikula
Browse files

drm/i915/gtt: Defer the free for alloc error paths

If we hit an error while allocating the page tables, we have to unwind
the incomplete updates, and wish to free the unused pd. However, we are
not allowed to be hoding the spinlock at that point, and so must use the
later free to defer it until after we drop the lock.

<3> [414.363795] BUG: sleeping function called from invalid context at drivers/gpu/drm/i915/i915_gem_gtt.c:472
<3> [414.364167] in_atomic(): 1, irqs_disabled(): 0, pid: 3905, name: i915_selftest
<4> [414.364406] 3 locks held by i915_selftest/3905:
<4> [414.364408]  #0: 0000000034fe8aa8 (&dev->mutex){....}, at: device_driver_attach+0x18/0x50
<4> [414.364415]  #1: 000000006bd8a560 (&dev->struct_mutex){+.+.}, at: igt_ctx_exec+0xb7/0x410 [i915]
<4> [414.364476]  #2: 000000003dfdc766 (&(&pd->lock)->rlock){+.+.}, at: gen8_ppgtt_alloc_pdp+0x448/0x540 [i915]
<3> [414.364529] Preemption disabled at:
<4> [414.364530] [<0000000000000000>] 0x0
<4> [414.364696] CPU: 0 PID: 3905 Comm: i915_selftest Tainted: G     U            5.2.0-rc7-CI-CI_DRM_6403+ #1
<4> [414.364698] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.1-0-g8891697-prebuilt.qemu-project.org 04/01/2014
<4> [414.364699] Call Trace:
<4> [414.364704]  dump_stack+0x67/0x9b
<4> [414.364708]  ___might_sleep+0x167/0x250
<4> [414.364777]  vm_free_page+0x24/0xc0 [i915]
<4> [414.364852]  free_pd+0xf/0x20 [i915]
<4> [414.364897]  gen8_ppgtt_alloc_pdp+0x489/0x540 [i915]
<4> [414.364946]  gen8_ppgtt_alloc_4lvl+0x8e/0x2e0 [i915]
<4> [414.364992]  ppgtt_bind_vma+0x2e/0x60 [i915]
<4> [414.365039]  i915_vma_bind+0xe8/0x2c0 [i915]
<4> [414.365088]  __i915_vma_do_pin+0xa1/0xd20 [i915]

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111050
Fixes: 1d1b5490

 ("drm/i915/gtt: Replace struct_mutex serialisation for allocation")
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190703171913.16585-3-chris@chris-wilson.co.uk
(cherry picked from commit 06861089

)
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
parent d1b739f3
......@@ -1446,7 +1446,8 @@ unwind_pd:
gen8_ppgtt_set_pdpe(pdp, vm->scratch_pd, pdpe);
GEM_BUG_ON(!atomic_read(&pdp->used));
atomic_dec(&pdp->used);
free_pd(vm, pd);
GEM_BUG_ON(alloc);
alloc = pd; /* defer the free to after the lock */
}
spin_unlock(&pdp->lock);
unwind:
......@@ -1515,7 +1516,8 @@ unwind_pdp:
spin_lock(&pml4->lock);
if (atomic_dec_and_test(&pdp->used)) {
gen8_ppgtt_set_pml4e(pml4, vm->scratch_pdp, pml4e);
free_pd(vm, pdp);
GEM_BUG_ON(alloc);
alloc = pdp; /* defer the free until after the lock */
}
spin_unlock(&pml4->lock);
unwind:
......
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