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-Url: https://git.stricted.de/?a=commitdiff_plain;h=9ab3b598d2df;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git mm: hwpoison: drop lru_add_drain_all() in __soft_offline_page() 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 Cc: [3.11+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 1a735fad2a13..d487f8dc6d39 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1646,8 +1646,6 @@ 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);