2020년 7월 15일 (수) 오후 5:24, Vlastimil Babka vbabka@suse.cz님이 작성:
On 7/15/20 7:05 AM, js1304@gmail.com wrote:
From: Joonsoo Kim iamjoonsoo.kim@lge.com
Currently, preventing cma area in page allocation is implemented by using current_gfp_context(). However, there are two problems of this implementation.
First, this doesn't work for allocation fastpath. In the fastpath, original gfp_mask is used since current_gfp_context() is introduced in order to control reclaim and it is on slowpath. Second, clearing __GFP_MOVABLE has a side effect to exclude the memory on the ZONE_MOVABLE for allocation target.
To fix these problems, this patch changes the implementation to exclude cma area in page allocation. Main point of this change is using the alloc_flags. alloc_flags is mainly used to control allocation so it fits for excluding cma area in allocation.
Agreed, should have been done with ALLOC_CMA since the beginning.
Fixes: d7fefcc (mm/cma: add PF flag to force non cma alloc)
More digits please. Fixes: d7fefcc8de91 ("mm/cma: add PF flag to force non cma alloc")
Will do.
Cc: stable@vger.kernel.org Signed-off-by: Joonsoo Kim iamjoonsoo.kim@lge.com
include/linux/sched/mm.h | 4 ---- mm/page_alloc.c | 27 +++++++++++++++------------ 2 files changed, 15 insertions(+), 16 deletions(-)
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index 44ad5b7..a73847a 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -191,10 +191,6 @@ static inline gfp_t current_gfp_context(gfp_t flags) flags &= ~(__GFP_IO | __GFP_FS); else if (pflags & PF_MEMALLOC_NOFS) flags &= ~__GFP_FS;
Above this hunk you should also remove PF_MEMALLOC_NOCMA from the test.
Will do.
-#ifdef CONFIG_CMA
if (pflags & PF_MEMALLOC_NOCMA)flags &= ~__GFP_MOVABLE;-#endif } return flags; } diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6416d08..cd53894 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2791,7 +2791,7 @@ __rmqueue(struct zone *zone, unsigned int order, int migratetype, * allocating from CMA when over half of the zone's free memory * is in the CMA area. */
if (migratetype == MIGRATE_MOVABLE &&
if (alloc_flags & ALLOC_CMA && zone_page_state(zone, NR_FREE_CMA_PAGES) > zone_page_state(zone, NR_FREE_PAGES) / 2) { page = __rmqueue_cma_fallback(zone, order);@@ -2802,7 +2802,7 @@ __rmqueue(struct zone *zone, unsigned int order, int migratetype, retry: page = __rmqueue_smallest(zone, order, migratetype); if (unlikely(!page)) {
if (migratetype == MIGRATE_MOVABLE)
if (alloc_flags & ALLOC_CMA) page = __rmqueue_cma_fallback(zone, order); if (!page && __rmqueue_fallback(zone, order, migratetype,@@ -3502,11 +3502,9 @@ static inline long __zone_watermark_unusable_free(struct zone *z, if (likely(!alloc_harder)) unusable_free += z->nr_reserved_highatomic;
-#ifdef CONFIG_CMA /* If allocation can't use CMA areas don't use free CMA pages */
if (!(alloc_flags & ALLOC_CMA))
if (IS_ENABLED(CONFIG_CMA) && !(alloc_flags & ALLOC_CMA)) unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);-#endif
return unusable_free;} @@ -3693,6 +3691,16 @@ alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask) return alloc_flags; }
+static inline void current_alloc_flags(gfp_t gfp_mask,
unsigned int *alloc_flags)+{
unsigned int pflags = READ_ONCE(current->flags);if (!(pflags & PF_MEMALLOC_NOCMA) &&gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)*alloc_flags |= ALLOC_CMA;+}
I don't like the modification through parameter, would just do what current_gfp_context() does and return the modified value. Also make it a no-op (including no READ_ONCE(current->flags)) if !CONFIG_CMA, please.
Okay.
/*
- get_page_from_freelist goes through the zonelist trying to allocate
- a page.
@@ -3706,6 +3714,8 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, struct pglist_data *last_pgdat_dirty_limit = NULL; bool no_fallback;
current_alloc_flags(gfp_mask, &alloc_flags);I don't see why to move the test here? It will still be executed in the fastpath, if that's what you wanted to avoid.
I want to execute it on the fastpath, too. Reason that I moved it here is that alloc_flags could be reset on slowpath. See the code where __gfp_pfmemalloc_flags() is on. This is the only place that I can apply this option to all the allocation paths at once.
Thanks.
retry: /* * Scan zonelist, looking for a zone with enough free. @@ -4339,10 +4349,6 @@ gfp_to_alloc_flags(gfp_t gfp_mask) } else if (unlikely(rt_task(current)) && !in_interrupt()) alloc_flags |= ALLOC_HARDER;
-#ifdef CONFIG_CMA
if (gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)alloc_flags |= ALLOC_CMA;-#endif
I would just replace this here with: alloc_flags = current_alloc_flags(gfp_mask, alloc_flags);
return alloc_flags;}
@@ -4808,9 +4814,6 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order, if (should_fail_alloc_page(gfp_mask, order)) return false;
if (IS_ENABLED(CONFIG_CMA) && ac->migratetype == MIGRATE_MOVABLE)*alloc_flags |= ALLOC_CMA;And same here... Ah, I see. current_alloc_flags() should probably take a migratetype parameter instead of gfp_mask then.
return true;}