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Dmitry Osipenko authored
Consider this scenario: 1. APP1 continuously creates lots of small GEMs 2. APP2 triggers `drop_caches` 3. Shrinker starts to evict APP1 GEMs, while APP1 produces new purgeable GEMs 4. msm_gem_shrinker_scan() returns non-zero number of freed pages and causes shrinker to try shrink more 5. msm_gem_shrinker_scan() returns non-zero number of freed pages again, goto 4 6. The APP2 is blocked in `drop_caches` until APP1 stops producing purgeable GEMs To prevent this blocking scenario, check number of remaining pages that GPU shrinker couldn't release due to a GEM locking contention or shrinking rejection. If there are no remaining pages left to shrink, then there is no need to free up more pages and shrinker may break out from the loop. This problem was found during shrinker/madvise IOCTL testing of virtio-gpu driver. The MSM driver is affected in the same way. Reviewed-by:
Rob Clark <robdclark@gmail.com> Reviewed-by:
Thomas Zimmermann <tzimmermann@suse.de> Fixes: b352ba54 ("drm/msm/gem: Convert to using drm_gem_lru") Signed-off-by:
Dmitry Osipenko <dmitry.osipenko@collabora.com> Link: https://lore.kernel.org/all/20230108210445.3948344-2-dmitry.osipenko@collabora.com/
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