From 251f9562b2ff5f549c5cbd79cd3edf0751b530fc Mon Sep 17 00:00:00 2001 From: Chris Wilson 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: 250e448c7731 ("drm/i915/gtt: Replace struct_mutex serialisation for allocation") Signed-off-by: Chris Wilson Cc: Matthew Auld Cc: Mika Kuoppala Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20190703171913.16585-3-chris@chris-wilson.co.uk --- 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 9e76347e039e8..1065753e86fb3 100644 --- a/drivers/gpu/drm/i915/i915_gem_gtt.c +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c @@ -1489,7 +1489,8 @@ 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: @@ -1558,7 +1559,8 @@ 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: -- 2.39.5