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authorKemeng Shi <shikemeng@huaweicloud.com>2023-09-27 17:44:01 +0800
committerAndrew Morton <akpm@linux-foundation.org>2023-10-06 14:11:38 -0700
commit61e21cf2d2c3cc5e60e8d0a62a77e250fccda62c (patch)
tree26ddbb49a94ebbe3b1a7f75235e501c3331c4d5a /mm/page_alloc.c
parent8a749fd1a8720d4619c91c8b6e7528c0a355c0aa (diff)
mm/page_alloc: correct start page when guard page debug is enabled
When guard page debug is enabled and set_page_guard returns success, we miss to forward page to point to start of next split range and we will do split unexpectedly in page range without target page. Move start page update before set_page_guard to fix this. As we split to wrong target page, then splited pages are not able to merge back to original order when target page is put back and splited pages except target page is not usable. To be specific: Consider target page is the third page in buddy page with order 2. | buddy-2 | Page | Target | Page | After break down to target page, we will only set first page to Guard because of bug. | Guard | Page | Target | Page | When we try put_page_back_buddy with target page, the buddy page of target if neither guard nor buddy, Then it's not able to construct original page with order 2 | Guard | Page | buddy-0 | Page | All pages except target page is not in free list and is not usable. Link: https://lkml.kernel.org/r/20230927094401.68205-1-shikemeng@huaweicloud.com Fixes: 06be6ff3d2ec ("mm,hwpoison: rework soft offline for free pages") Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 95546f376302..85741403948f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6475,6 +6475,7 @@ static void break_down_buddy_pages(struct zone *zone, struct page *page,
next_page = page;
current_buddy = page + size;
}
+ page = next_page;
if (set_page_guard(zone, current_buddy, high, migratetype))
continue;
@@ -6482,7 +6483,6 @@ static void break_down_buddy_pages(struct zone *zone, struct page *page,
if (current_buddy != target) {
add_to_free_list(current_buddy, zone, high, migratetype);
set_buddy_order(current_buddy, high);
- page = next_page;
}
}
}