Re: Suspicious error for CMA stress test
From: Joonsoo Kim <hidden>
Date: 2016-03-14 07:17:17
Also in:
linux-arm-kernel, linux-mm
Subsystem:
memory management, memory management - page allocator, the rest · Maintainers:
Andrew Morton, Vlastimil Babka, Linus Torvalds
On Mon, Mar 14, 2016 at 08:06:16AM +0100, Vlastimil Babka wrote:
On 03/14/2016 07:49 AM, Joonsoo Kim wrote:quoted
On Fri, Mar 11, 2016 at 06:07:40PM +0100, Vlastimil Babka wrote:quoted
On 03/11/2016 04:00 PM, Joonsoo Kim wrote: How about something like this? Just and idea, probably buggy (off-by-one etc.). Should keep away cost from <pageblock_order iterations at the expense of the relatively fewer >pageblock_order iterations.Hmm... I tested this and found that it's code size is a little bit larger than mine. I'm not sure why this happens exactly but I guess it would be related to compiler optimization. In this case, I'm in favor of my implementation because it looks like well abstraction. It adds one unlikely branch to the merge loop but compiler would optimize it to check it once.I would be surprised if compiler optimized that to check it once, as order increases with each loop iteration. But maybe it's smart enough to do something like I did by hand? Guess I'll check the disassembly.
Okay. I used following slightly optimized version and I need to add 'max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1)' to yours. Please consider it, too. Thanks. ------------------------>8------------------------
From 36b8ffdaa0e7a8d33fd47a62a35a9e507e3e62e9 Mon Sep 17 00:00:00 2001
From: Joonsoo Kim <redacted> Date: Mon, 14 Mar 2016 15:20:07 +0900 Subject: [PATCH] mm: fix cma Signed-off-by: Joonsoo Kim <redacted> --- mm/page_alloc.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0bb933a..f7baa4f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c@@ -627,8 +627,8 @@ static inline void rmv_page_order(struct page *page) * * For recording page's order, we use page_private(page). */ -static inline int page_is_buddy(struct page *page, struct page *buddy, - unsigned int order) +static inline int page_is_buddy(struct zone *zone, struct page *page, + struct page *buddy, unsigned int order, int mt) { if (!pfn_valid_within(page_to_pfn(buddy))) return 0;
@@ -651,6 +651,15 @@ static inline int page_is_buddy(struct page *page, struct page *buddy, if (page_zone_id(page) != page_zone_id(buddy)) return 0; + if (unlikely(has_isolate_pageblock(zone) && + order >= pageblock_order)) { + int buddy_mt = get_pageblock_migratetype(buddy); + + if (mt != buddy_mt && (is_migrate_isolate(mt) || + is_migrate_isolate(buddy_mt))) + return 0; + } + VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy); return 1;
@@ -698,17 +707,8 @@ static inline void __free_one_page(struct page *page, VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page); VM_BUG_ON(migratetype == -1); - if (is_migrate_isolate(migratetype)) { - /* - * We restrict max order of merging to prevent merge - * between freepages on isolate pageblock and normal - * pageblock. Without this, pageblock isolation - * could cause incorrect freepage accounting. - */ - max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1); - } else { + if (!is_migrate_isolate(migratetype)) __mod_zone_freepage_state(zone, 1 << order, migratetype); - } page_idx = pfn & ((1 << max_order) - 1);
@@ -718,7 +718,7 @@ static inline void __free_one_page(struct page *page, while (order < max_order - 1) { buddy_idx = __find_buddy_index(page_idx, order); buddy = page + (buddy_idx - page_idx); - if (!page_is_buddy(page, buddy, order)) + if (!page_is_buddy(zone, page, buddy, order, migratetype)) break; /* * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
@@ -752,7 +752,8 @@ static inline void __free_one_page(struct page *page, higher_page = page + (combined_idx - page_idx); buddy_idx = __find_buddy_index(combined_idx, order + 1); higher_buddy = higher_page + (buddy_idx - combined_idx); - if (page_is_buddy(higher_page, higher_buddy, order + 1)) { + if (page_is_buddy(zone, higher_page, higher_buddy, + order + 1, migratetype)) { list_add_tail(&page->lru, &zone->free_area[order].free_list[migratetype]); goto out;
--
1.9.1