From f691eaa4801484fffc8a2bcb24caa27fb2edcce3 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 3 Jul 2019 18:19:12 +0100
Subject: [PATCH] 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: 1d1b5490b91c ("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 068610895ebd4bd86f496f01eb7b97e56d7269b2)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
drivers/gpu/drm/i915/i915_gem_gtt.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 8ab820145ea6..50fe72d40d8b 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -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: