From eb2e2b425c6984ca8034448a3f2c680622bd3d4d Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Fri, 13 Jan 2023 11:12:14 +0000 Subject: [PATCH] mm/page_alloc: explicitly record high-order atomic allocations in alloc_flags A high-order ALLOC_HARDER allocation is assumed to be atomic. While that is accurate, it changes later in the series. In preparation, explicitly record high-order atomic allocations in gfp_to_alloc_flags(). Link: https://lkml.kernel.org/r/20230113111217.14134-4-mgorman@techsingularity.net Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka Acked-by: Michal Hocko Cc: Matthew Wilcox Cc: NeilBrown Cc: Thierry Reding Signed-off-by: Andrew Morton --- mm/internal.h | 1 + mm/page_alloc.c | 29 +++++++++++++++++++++++------ 2 files changed, 24 insertions(+), 6 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 99eb544fbded..62428467d7cf 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -789,6 +789,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, #else #define ALLOC_NOFRAGMENT 0x0 #endif +#define ALLOC_HIGHATOMIC 0x200 /* Allows access to MIGRATE_HIGHATOMIC */ #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */ enum ttu_flags; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4f5c2e83cb7b..8a7e1cfa8353 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3724,10 +3724,20 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone, * reserved for high-order atomic allocation, so order-0 * request should skip it. */ - if (order > 0 && alloc_flags & ALLOC_HARDER) + if (alloc_flags & ALLOC_HIGHATOMIC) page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); if (!page) { page = __rmqueue(zone, order, migratetype, alloc_flags); + + /* + * If the allocation fails, allow OOM handling access + * to HIGHATOMIC reserves as failing now is worse than + * failing a high-order atomic allocation in the + * future. + */ + if (!page && (alloc_flags & ALLOC_OOM)) + page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); + if (!page) { spin_unlock_irqrestore(&zone->lock, flags); return NULL; @@ -4041,8 +4051,10 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, return true; } #endif - if (alloc_harder && !free_area_empty(area, MIGRATE_HIGHATOMIC)) + if ((alloc_flags & (ALLOC_HIGHATOMIC|ALLOC_OOM)) && + !free_area_empty(area, MIGRATE_HIGHATOMIC)) { return true; + } } return false; } @@ -4304,7 +4316,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, * If this is a high-order atomic allocation then check * if the pageblock should be reserved for the future */ - if (unlikely(order && (alloc_flags & ALLOC_HARDER))) + if (unlikely(alloc_flags & ALLOC_HIGHATOMIC)) reserve_highatomic_pageblock(page, zone, order); return page; @@ -4831,7 +4843,7 @@ static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask, } static inline unsigned int -gfp_to_alloc_flags(gfp_t gfp_mask) +gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order) { unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET; @@ -4857,8 +4869,13 @@ gfp_to_alloc_flags(gfp_t gfp_mask) * Not worth trying to allocate harder for __GFP_NOMEMALLOC even * if it can't schedule. */ - if (!(gfp_mask & __GFP_NOMEMALLOC)) + if (!(gfp_mask & __GFP_NOMEMALLOC)) { alloc_flags |= ALLOC_HARDER; + + if (order > 0) + alloc_flags |= ALLOC_HIGHATOMIC; + } + /* * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the * comment for __cpuset_node_allowed(). @@ -5066,7 +5083,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, * kswapd needs to be woken up, and to avoid the cost of setting up * alloc_flags precisely. So we do that now. */ - alloc_flags = gfp_to_alloc_flags(gfp_mask); + alloc_flags = gfp_to_alloc_flags(gfp_mask, order); /* * We need to recalculate the starting point for the zonelist iterator