From: Naoya Horiguchi Date: Thu, 12 Feb 2015 23:00:25 +0000 (-0800) Subject: mm: hwpoison: drop lru_add_drain_all() in __soft_offline_page() X-Git-Tag: v3.19.2~138 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1bab6ee0b41e4fa4550693da82742aa50a94290c;p=thirdparty%2Fkernel%2Fstable.git mm: hwpoison: drop lru_add_drain_all() in __soft_offline_page() commit 9ab3b598d2dfbdb0153ffa7e4b1456bbff59a25d upstream. A race condition starts to be visible in recent mmotm, where a PG_hwpoison flag is set on a migration source page *before* it's back in buddy page poo= l. This is problematic because no page flag is supposed to be set when freeing (see __free_one_page().) So the user-visible effect of this race is that it could trigger the BUG_ON() when soft-offlining is called. The root cause is that we call lru_add_drain_all() to make sure that the page is in buddy, but that doesn't work because this function just schedule= s a work item and doesn't wait its completion. drain_all_pages() does drainin= g directly, so simply dropping lru_add_drain_all() solves this problem. Fixes: f15bdfa802bf ("mm/memory-failure.c: fix memory leak in successful soft offlining") Signed-off-by: Naoya Horiguchi Cc: Andi Kleen Cc: Tony Luck Cc: Chen Gong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/mm/memory-failure.c b/mm/memory-failure.c index feb803bf34436..20c29ddff17b2 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1653,8 +1653,6 @@ static int __soft_offline_page(struct page *page, int flags) * source page should be freed back to buddy before * setting PG_hwpoison. */ - if (!is_free_buddy_page(page)) - lru_add_drain_all(); if (!is_free_buddy_page(page)) drain_all_pages(page_zone(page)); SetPageHWPoison(page);