mm, drm/i915: mark pinned shmemfs pages as unevictable

The i915 driver uses shmemfs to allocate backing storage for gem
objects. These shmemfs pages can be pinned (increased ref count) by
shmem_read_mapping_page_gfp(). When a lot of pages are pinned, vmscan
wastes a lot of time scanning these pinned pages. In some extreme case,
all pages in the inactive anon lru are pinned, and only the inactive
anon lru is scanned due to inactive_ratio, the system cannot swap and
invokes the oom-killer. Mark these pinned pages as unevictable to speed
up vmscan.

Export pagevec API check_move_unevictable_pages().

This patch was inspired by Chris Wilson's change [1].

[1]: https://patchwork.kernel.org/patch/9768741/

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Kuo-Hsin Yang <vovoy@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.com> # mm part
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181106132324.17390-1-chris@chris-wilson.co.uk
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 29 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 347b3836c809..5b80b0c14aed 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2382,11 +2382,23 @@ void __i915_gem_object_invalidate(struct drm_i915_gem_object *obj)
 	invalidate_mapping_pages(mapping, 0, (loff_t)-1);
 }
 
+/*
+ * Move pages to appropriate lru and release the pagevec, decrementing the
+ * ref count of those pages.
+ */
+static void check_release_pagevec(struct pagevec *pvec)
+{
+	check_move_unevictable_pages(pvec);
+	__pagevec_release(pvec);
+	cond_resched();
+}
+
 static void
 i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj,
 			      struct sg_table *pages)
 {
 	struct sgt_iter sgt_iter;
+	struct pagevec pvec;
 	struct page *page;
 
 	__i915_gem_object_release_shmem(obj, pages, true);
@@ -2396,6 +2408,9 @@ i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj,
 	if (i915_gem_object_needs_bit17_swizzle(obj))
 		i915_gem_object_save_bit_17_swizzle(obj, pages);
 
+	mapping_clear_unevictable(file_inode(obj->base.filp)->i_mapping);
+
+	pagevec_init(&pvec);
 	for_each_sgt_page(page, sgt_iter, pages) {
 		if (obj->mm.dirty)
 			set_page_dirty(page);
@@ -2403,9 +2418,11 @@ i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj,
 		if (obj->mm.madv == I915_MADV_WILLNEED)
 			mark_page_accessed(page);
 
-		put_page(page);
-		cond_resched();
+		if (!pagevec_add(&pvec, page))
+			check_release_pagevec(&pvec);
 	}
+	if (pagevec_count(&pvec))
+		check_release_pagevec(&pvec);
 	obj->mm.dirty = false;
 
 	sg_free_table(pages);
@@ -2526,6 +2543,7 @@ static int i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 	unsigned long last_pfn = 0;	/* suppress gcc warning */
 	unsigned int max_segment = i915_sg_segment_size();
 	unsigned int sg_page_sizes;
+	struct pagevec pvec;
 	gfp_t noreclaim;
 	int ret;
 
@@ -2561,6 +2579,7 @@ rebuild_st:
 	 * Fail silently without starting the shrinker
 	 */
 	mapping = obj->base.filp->f_mapping;
+	mapping_set_unevictable(mapping);
 	noreclaim = mapping_gfp_constraint(mapping, ~__GFP_RECLAIM);
 	noreclaim |= __GFP_NORETRY | __GFP_NOWARN;
 
@@ -2675,8 +2694,14 @@ rebuild_st:
 err_sg:
 	sg_mark_end(sg);
 err_pages:
-	for_each_sgt_page(page, sgt_iter, st)
-		put_page(page);
+	mapping_clear_unevictable(mapping);
+	pagevec_init(&pvec);
+	for_each_sgt_page(page, sgt_iter, st) {
+		if (!pagevec_add(&pvec, page))
+			check_release_pagevec(&pvec);
+	}
+	if (pagevec_count(&pvec))
+		check_release_pagevec(&pvec);
 	sg_free_table(st);
 	kfree(st);