From: Joonsoo Kim iamjoonsoo.kim@lge.com
mainline inclusion from mainline-v5.9-rc1 commit 8510e69c8efef82f2b37ea3e8ea19a27122c533e category: bugfix bugzilla: 34611 CVE: NA
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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.
Fixes: d7fefcc8de91 (mm/cma: add PF flag to force non cma alloc) Signed-off-by: Joonsoo Kim iamjoonsoo.kim@lge.com Signed-off-by: Andrew Morton akpm@linux-foundation.org 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 Link: http://lkml.kernel.org/r/1595468942-29687-1-git-send-email-iamjoonsoo.kim@lg... Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- include/linux/sched/mm.h | 8 +------- mm/page_alloc.c | 27 +++++++++++++++++++-------- 2 files changed, 20 insertions(+), 15 deletions(-)
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index c04db712c5d2..9457e8dd06c6 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -175,12 +175,10 @@ static inline bool in_vfork(struct task_struct *tsk) * 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 @@ -189,10 +187,6 @@ static inline gfp_t current_gfp_context(gfp_t flags) 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; } diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 1cc5dfa418d0..553875714352 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3338,6 +3338,20 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone) } #endif /* CONFIG_NUMA */
+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) && + gfpflags_to_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. @@ -3974,10 +3988,8 @@ gfp_to_alloc_flags(gfp_t gfp_mask) } else if (unlikely(rt_task(current)) && !in_interrupt()) alloc_flags |= ALLOC_HARDER;
-#ifdef CONFIG_CMA - if (gfpflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE) - alloc_flags |= ALLOC_CMA; -#endif + alloc_flags = current_alloc_flags(gfp_mask, alloc_flags); + return alloc_flags; }
@@ -4268,7 +4280,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
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 @@ -4345,7 +4357,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
/* 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;
@@ -4441,8 +4453,7 @@ 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; + *alloc_flags = current_alloc_flags(gfp_mask, *alloc_flags);
return true; }