diff options
| -rw-r--r-- | mm/page_alloc.c | 53 |
1 files changed, 39 insertions, 14 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 55e9c56dfe54..b8d560afe266 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2322,8 +2322,10 @@ static inline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) #endif /* CONFIG_FAIL_PAGE_ALLOC */ /* - * Return true if free pages are above 'mark'. This takes into account the order - * of the allocation. + * Return true if free base pages are above 'mark'. For high-order checks it + * will return true of the order-0 watermark is reached and there is at least + * one free page of a suitable size. Checking now avoids taking the zone lock + * to check in the allocation paths if no pages are free. */ static bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, int classzone_idx, int alloc_flags, @@ -2331,7 +2333,7 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order, { long min = mark; int o; - long free_cma = 0; + const int alloc_harder = (alloc_flags & ALLOC_HARDER); /* free_pages may go negative - that's OK */ free_pages -= (1 << order) - 1; @@ -2344,7 +2346,7 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order, * the high-atomic reserves. This will over-estimate the size of the * atomic reserve but it avoids a search. */ - if (likely(!(alloc_flags & ALLOC_HARDER))) + if (likely(!alloc_harder)) free_pages -= z->nr_reserved_highatomic; else min -= min / 4; @@ -2352,22 +2354,45 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order, #ifdef CONFIG_CMA /* If allocation can't use CMA areas don't use free CMA pages */ if (!(alloc_flags & ALLOC_CMA)) - free_cma = zone_page_state(z, NR_FREE_CMA_PAGES); + free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES); #endif - if (free_pages - free_cma <= min + z->lowmem_reserve[classzone_idx]) + /* + * Check watermarks for an order-0 allocation request. If these + * are not met, then a high-order request also cannot go ahead + * even if a suitable page happened to be free. + */ + if (free_pages <= min + z->lowmem_reserve[classzone_idx]) return false; - for (o = 0; o < order; o++) { - /* At the next order, this order's pages become unavailable */ - free_pages -= z->free_area[o].nr_free << o; - /* Require fewer higher order pages to be free */ - min >>= 1; + /* If this is an order-0 request then the watermark is fine */ + if (!order) + return true; + + /* For a high-order request, check at least one suitable page is free */ + for (o = order; o < MAX_ORDER; o++) { + struct free_area *area = &z->free_area[o]; + int mt; + + if (!area->nr_free) + continue; + + if (alloc_harder) + return true; - if (free_pages <= min) - return false; + for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) { + if (!list_empty(&area->free_list[mt])) + return true; + } + +#ifdef CONFIG_CMA + if ((alloc_flags & ALLOC_CMA) && + !list_empty(&area->free_list[MIGRATE_CMA])) { + return true; + } +#endif } - return true; + return false; } bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, |