+ mm-page_alloc-fix-memalloc_nocma_save-restore-apis.patch added to -mm tree - Linux-stable-mirror

24 Jul 2020

The patch titled
     Subject: mm/page_alloc: fix memalloc_nocma_{save/restore} APIs
has been added to the -mm tree.  Its filename is
     mm-page_alloc-fix-memalloc_nocma_save-restore-apis.patch
This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-fix-memalloc_nocma_sa...
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-fix-memalloc_nocma_sa...
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
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------------------------------------------------------
From: js1304@gmail.com
Subject: mm/page_alloc: fix memalloc_nocma_{save/restore} APIs
Currently, memalloc_nocma_{save/restore} API that prevents 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. So, CMA area can be
allocated through the allocation fastpath even if
memalloc_nocma_{save/restore} APIs are used. Currently, there is just
one user for these APIs and it has a fallback method to prevent actual
problem.
Second, clearing __GFP_MOVABLE in current_gfp_context() 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.
Link: http://lkml.kernel.org/r/1595468942-29687-1-git-send-email-iamjoonsoo.kim@lg...
Fixes: d7fefcc8de91 (mm/cma: add PF flag to force non cma alloc)
Signed-off-by: Joonsoo Kim iamjoonsoo.kim@lge.com
Reviewed-by: Vlastimil Babka vbabka@suse.cz
Cc: Christoph Hellwig hch@infradead.org
Cc: Roman Gushchin guro@fb.com
Cc: Mike Kravetz mike.kravetz@oracle.com
Cc: Naoya Horiguchi n-horiguchi@ah.jp.nec.com
Cc: Michal Hocko mhocko@suse.com
Cc: "Aneesh Kumar K . V" aneesh.kumar@linux.ibm.com
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton akpm@linux-foundation.org
---
include/linux/sched/mm.h |    8 +-------
 mm/page_alloc.c          |   31 +++++++++++++++++++++----------
 2 files changed, 22 insertions(+), 17 deletions(-)

--- a/include/linux/sched/mm.h~mm-page_alloc-fix-memalloc_nocma_save-restore-apis
+++ a/include/linux/sched/mm.h
@@ -177,12 +177,10 @@ static inline bool in_vfork(struct task_
  * Applies per-task gfp context to the given allocation flags.
  * PF_MEMALLOC_NOIO implies GFP_NOIO
  * PF_MEMALLOC_NOFS implies GFP_NOFS
- * PF_MEMALLOC_NOCMA implies no allocation from CMA region.
  */
 static inline gfp_t current_gfp_context(gfp_t flags)
 {
-	if (unlikely(current->flags &
-		     (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_NOCMA))) {
+	if (unlikely(current->flags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS))) {
    	/*
    	 * NOIO implies both NOIO and NOFS and it is a weaker context
    	 * so always make sure it makes precedence
@@ -191,10 +189,6 @@ static inline gfp_t current_gfp_context(
    		flags &= ~(__GFP_IO | __GFP_FS);
    	else if (current->flags & PF_MEMALLOC_NOFS)
    		flags &= ~__GFP_FS;
-#ifdef CONFIG_CMA
-		if (current->flags & PF_MEMALLOC_NOCMA)
-			flags &= ~__GFP_MOVABLE;
-#endif
    }
    return flags;
 }
--- a/mm/page_alloc.c~mm-page_alloc-fix-memalloc_nocma_save-restore-apis
+++ a/mm/page_alloc.c
@@ -2790,7 +2790,7 @@ __rmqueue(struct zone *zone, unsigned in
     * 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);
@@ -2801,7 +2801,7 @@ __rmqueue(struct zone *zone, unsigned in
 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,
@@ -3671,6 +3671,20 @@ alloc_flags_nofragment(struct zone *zone
    return alloc_flags;
 }
+static inline unsigned int current_alloc_flags(gfp_t gfp_mask,
+					unsigned int alloc_flags)
+{
+#ifdef CONFIG_CMA
+	unsigned int pflags = current->flags;
+
+	if (!(pflags & PF_MEMALLOC_NOCMA) &&
+			gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+		alloc_flags |= ALLOC_CMA;
+
+#endif
+	return alloc_flags;
+}
+
 /*
  * get_page_from_freelist goes through the zonelist trying to allocate
  * a page.
@@ -4316,10 +4330,8 @@ 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
+	alloc_flags = current_alloc_flags(gfp_mask, alloc_flags);
+
    return alloc_flags;
 }
@@ -4620,7 +4632,7 @@ retry:
reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
    if (reserve_flags)
-		alloc_flags = reserve_flags;
+		alloc_flags = current_alloc_flags(gfp_mask, reserve_flags);
/*
     * Reset the nodemask and zonelist iterators if memory policies can be
@@ -4697,7 +4709,7 @@ retry:
/* Avoid allocations with no watermarks from looping endlessly */
    if (tsk_is_oom_victim(current) &&
-	    (alloc_flags == ALLOC_OOM ||
+	    (alloc_flags & ALLOC_OOM ||
         (gfp_mask & __GFP_NOMEMALLOC)))
    	goto nopage;
@@ -4785,8 +4797,7 @@ static inline bool prepare_alloc_pages(g
    if (should_fail_alloc_page(gfp_mask, order))
    	return false;
-	if (IS_ENABLED(CONFIG_CMA) && ac->migratetype == MIGRATE_MOVABLE)
-		*alloc_flags |= ALLOC_CMA;
+	*alloc_flags = current_alloc_flags(gfp_mask, *alloc_flags);
return true;
 }
_
Patches currently in -mm which might be from iamjoonsoo.kim@lge.com are
mm-page_alloc-fix-memalloc_nocma_save-restore-apis.patch
mm-vmscan-make-active-inactive-ratio-as-1-1-for-anon-lru.patch
mm-vmscan-protect-the-workingset-on-anonymous-lru.patch
mm-workingset-prepare-the-workingset-detection-infrastructure-for-anon-lru.patch
mm-swapcache-support-to-handle-the-shadow-entries.patch
mm-swap-implement-workingset-detection-for-anonymous-lru.patch
mm-vmscan-restore-active-inactive-ratio-for-anonymous-lru.patch
mm-page_isolation-prefer-the-node-of-the-source-page.patch
mm-migrate-move-migration-helper-from-h-to-c.patch
mm-hugetlb-unify-migration-callbacks.patch
mm-migrate-clear-__gfp_reclaim-to-make-the-migration-callback-consistent-with-regular-thp-allocations.patch
mm-migrate-make-a-standard-migration-target-allocation-function.patch
mm-mempolicy-use-a-standard-migration-target-allocation-callback.patch
mm-page_alloc-remove-a-wrapper-for-alloc_migration_target.patch
mm-memory-failure-remove-a-wrapper-for-alloc_migration_target.patch
mm-memory_hotplug-remove-a-wrapper-for-alloc_migration_target.patch

    