Since dropping the set-to-gtt-domain in commit a679f58d0510 ("drm/i915: Flush pages on acquisition"), we no longer mark the contents as dirty on a write fault. This has the issue of us then not marking the pages as dirty on releasing the buffer, which means the contents are not written out to the swap device (should we ever pick that buffer as a victim). Notably, this is visible in the dumb buffer interface used for cursors. Having updated the cursor contents via mmap, and swapped away, if the shrinker should evict the old cursor, upon next reuse, the cursor would be invisible.
E.g. echo 80 > /proc/sys/kernel/sysrq ; echo f > /proc/sysrq-trigger
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111541 Fixes: a679f58d0510 ("drm/i915: Flush pages on acquisition") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Matthew Auld matthew.william.auld@gmail.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: stable@vger.kernel.org # v5.2+ --- drivers/gpu/drm/i915/gem/i915_gem_mman.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c index 1748e63156a2..860b751c51f1 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c @@ -319,7 +319,11 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) intel_wakeref_auto(&i915->ggtt.userfault_wakeref, msecs_to_jiffies_timeout(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND));
- i915_vma_set_ggtt_write(vma); + if (write) { + GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj)); + i915_vma_set_ggtt_write(vma); + obj->mm.dirty = true; + }
err_fence: i915_vma_unpin_fence(vma);
Quoting Chris Wilson (2019-09-20 13:18:21)
Since dropping the set-to-gtt-domain in commit a679f58d0510 ("drm/i915: Flush pages on acquisition"), we no longer mark the contents as dirty on a write fault. This has the issue of us then not marking the pages as dirty on releasing the buffer, which means the contents are not written out to the swap device (should we ever pick that buffer as a victim). Notably, this is visible in the dumb buffer interface used for cursors. Having updated the cursor contents via mmap, and swapped away, if the shrinker should evict the old cursor, upon next reuse, the cursor would be invisible.
Hmm, I think the dumb interface may be missing a few steps around the place to ensure the contents are flushed. -Chris
Quoting Chris Wilson (2019-09-20 13:22:13)
Quoting Chris Wilson (2019-09-20 13:18:21)
Since dropping the set-to-gtt-domain in commit a679f58d0510 ("drm/i915: Flush pages on acquisition"), we no longer mark the contents as dirty on a write fault. This has the issue of us then not marking the pages as dirty on releasing the buffer, which means the contents are not written out to the swap device (should we ever pick that buffer as a victim). Notably, this is visible in the dumb buffer interface used for cursors. Having updated the cursor contents via mmap, and swapped away, if the shrinker should evict the old cursor, upon next reuse, the cursor would be invisible.
Hmm, I think the dumb interface may be missing a few steps around the place to ensure the contents are flushed.
No, it's fine. We do the flush in pinning pages, the only thing that was dropped was then marking the content as dirty. -Chris
On Fri, 20 Sep 2019 at 13:18, Chris Wilson chris@chris-wilson.co.uk wrote:
Since dropping the set-to-gtt-domain in commit a679f58d0510 ("drm/i915: Flush pages on acquisition"), we no longer mark the contents as dirty on a write fault. This has the issue of us then not marking the pages as dirty on releasing the buffer, which means the contents are not written out to the swap device (should we ever pick that buffer as a victim). Notably, this is visible in the dumb buffer interface used for cursors. Having updated the cursor contents via mmap, and swapped away, if the shrinker should evict the old cursor, upon next reuse, the cursor would be invisible.
E.g. echo 80 > /proc/sys/kernel/sysrq ; echo f > /proc/sysrq-trigger
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111541 Fixes: a679f58d0510 ("drm/i915: Flush pages on acquisition") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Matthew Auld matthew.william.auld@gmail.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: stable@vger.kernel.org # v5.2+
Reviewed-by: Matthew Auld matthew.william.auld@gmail.com
linux-stable-mirror@lists.linaro.org
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Chris Wilson -
Matthew Auld