Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752478AbaL3KR7 (ORCPT ); Tue, 30 Dec 2014 05:17:59 -0500 Received: from mx1.mxmail.xiaomi.com ([58.68.235.87]:45147 "EHLO mx1.mxmail.xiaomi.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751993AbaL3KR6 (ORCPT ); Tue, 30 Dec 2014 05:17:58 -0500 From: Hui Zhu To: , , , , , , , , , , CC: , Hui Zhu , Weixing Liu Subject: [PATCH] CMA: Fix CMA's page number is substructed twice in __zone_watermark_ok Date: Tue, 30 Dec 2014 18:17:25 +0800 Message-ID: <1419934645-20106-1-git-send-email-zhuhui@xiaomi.com> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [172.27.14.101] X-ClientProxiedBy: CNCAS3.mioffice.cn (10.237.8.133) To cnbox3.mioffice.cn (10.237.8.143) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The original of this patch [1] is used to fix the issue in Joonsoo's CMA patch "CMA: always treat free cma pages as non-free on watermark checking" [2]. Joonsoo reminded me that this issue affect current kernel too. So made a new one for upstream. Function __zone_watermark_ok substruct CMA pages number from free_pages if system allocation can't use CMA areas: /* 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); But after this part of code 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; CMA memory in each order is part of z->free_area[o].nr_free, then the CMA page number of this order is substructed twice. This bug will make __zone_watermark_ok return more false. This patch add cma_free_area to struct free_area that just record the number of CMA pages. And add it back in the order loop to handle the substruct twice issue. [1] https://lkml.org/lkml/2014/12/25/43 [2] https://lkml.org/lkml/2014/5/28/110 Signed-off-by: Hui Zhu Signed-off-by: Weixing Liu --- include/linux/mmzone.h | 3 +++ mm/page_alloc.c | 22 ++++++++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 2f0856d..094476b 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -92,6 +92,9 @@ static inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn) struct free_area { struct list_head free_list[MIGRATE_TYPES]; unsigned long nr_free; +#ifdef CONFIG_CMA + unsigned long cma_nr_free; +#endif }; struct pglist_data; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7633c50..026cf27 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -650,6 +650,8 @@ static inline void __free_one_page(struct page *page, } else { list_del(&buddy->lru); zone->free_area[order].nr_free--; + if (is_migrate_cma(migratetype)) + zone->free_area[order].cma_nr_free--; rmv_page_order(buddy); } combined_idx = buddy_idx & page_idx; @@ -683,6 +685,8 @@ static inline void __free_one_page(struct page *page, list_add(&page->lru, &zone->free_area[order].free_list[migratetype]); out: zone->free_area[order].nr_free++; + if (is_migrate_cma(migratetype)) + zone->free_area[order].cma_nr_free++; } static inline int free_pages_check(struct page *page) @@ -937,6 +941,8 @@ static inline void expand(struct zone *zone, struct page *page, } list_add(&page[size].lru, &area->free_list[migratetype]); area->nr_free++; + if (is_migrate_cma(migratetype)) + area->cma_nr_free++; set_page_order(&page[size], high); } } @@ -1020,6 +1026,8 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order, list_del(&page->lru); rmv_page_order(page); area->nr_free--; + if (is_migrate_cma(migratetype)) + area->cma_nr_free--; expand(zone, page, order, current_order, area, migratetype); set_freepage_migratetype(page, migratetype); return page; @@ -1208,6 +1216,8 @@ __rmqueue_fallback(struct zone *zone, unsigned int order, int start_migratetype) page = list_entry(area->free_list[migratetype].next, struct page, lru); area->nr_free--; + if (is_migrate_cma(migratetype)) + area->cma_nr_free--; new_type = try_to_steal_freepages(zone, page, start_migratetype, @@ -1597,6 +1607,8 @@ int __isolate_free_page(struct page *page, unsigned int order) /* Remove page from free list */ list_del(&page->lru); zone->free_area[order].nr_free--; + if (is_migrate_cma(mt)) + zone->free_area[order].cma_nr_free--; rmv_page_order(page); /* Set the pageblock if the isolated page is at least a pageblock */ @@ -1827,6 +1839,13 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order, /* At the next order, this order's pages become unavailable */ free_pages -= z->free_area[o].nr_free << o; + /* If CMA's page number of this order was substructed as part + of "zone_page_state(z, NR_FREE_CMA_PAGES)", subtracting + "z->free_area[o].nr_free << o" substructed CMA's page + number of this order again. So add it back. */ + if (IS_ENABLED(CONFIG_CMA) && free_cma) + free_pages += z->free_area[o].cma_nr_free << o; + /* Require fewer higher order pages to be free */ min >>= 1; @@ -4238,6 +4257,7 @@ static void __meminit zone_init_free_lists(struct zone *zone) for_each_migratetype_order(order, t) { INIT_LIST_HEAD(&zone->free_area[order].free_list[t]); zone->free_area[order].nr_free = 0; + zone->free_area[order].cma_nr_free = 0; } } @@ -6610,6 +6630,8 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) list_del(&page->lru); rmv_page_order(page); zone->free_area[order].nr_free--; + if (is_migrate_cma(get_pageblock_migratetype(page))) + zone->free_area[order].cma_nr_free--; for (i = 0; i < (1 << order); i++) SetPageReserved((page+i)); pfn += (1 << order); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/