From 3e030ecc0fc7de10fd0da10c1c19939872a31717 Mon Sep 17 00:00:00 2001 From: Naoya Horiguchi Date: Thu, 22 May 2014 11:54:21 -0700 Subject: [PATCH] mm/memory-failure.c: fix memory leak by race between poison and unpoison When a memory error happens on an in-use page or (free and in-use) hugepage, the victim page is isolated with its refcount set to one. When you try to unpoison it later, unpoison_memory() calls put_page() for it twice in order to bring the page back to free page pool (buddy or free hugepage list). However, if another memory error occurs on the page which we are unpoisoning, memory_failure() returns without releasing the refcount which was incremented in the same call at first, which results in memory leak and unconsistent num_poisoned_pages statistics. This patch fixes it. Signed-off-by: Naoya Horiguchi Cc: Andi Kleen Cc: [2.6.32+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory-failure.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index dbf8922216ad..9ccef39a9de2 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1153,6 +1153,8 @@ int memory_failure(unsigned long pfn, int trapno, int flags) */ if (!PageHWPoison(p)) { printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn); + atomic_long_sub(nr_pages, &num_poisoned_pages); + put_page(hpage); res = 0; goto out; } -- 2.20.1