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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: 1d1b5490b9 ("drm/i915/gtt: Replace struct_mutex serialisation for allocation")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika 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 068610895e)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Chris Wilson 2019-07-03 18:19:12 +01:00 committed by Jani Nikula
parent d1b739f326
commit f691eaa480
1 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/gpu/drm/i915/i915_gem_gtt.c
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@ -1446,7 +1446,8 @@ static int gen8_ppgtt_alloc_pdp(struct i915_address_space *vm,
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 @@ static int gen8_ppgtt_alloc_4lvl(struct i915_address_space *vm,
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: