Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755854AbaKROUl (ORCPT ); Tue, 18 Nov 2014 09:20:41 -0500 Received: from cantor2.suse.de ([195.135.220.15]:56996 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932234AbaKROKY (ORCPT ); Tue, 18 Nov 2014 09:10:24 -0500 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Yu Zhao , Andrea Arcangeli , Mel Gorman , David Rientjes , Bob Liu , Andrew Morton , Linus Torvalds , Jiri Slaby Subject: [PATCH 3.12 172/206] mm: free compound page with correct order Date: Tue, 18 Nov 2014 15:08:47 +0100 Message-Id: X-Mailer: git-send-email 2.1.3 In-Reply-To: <28f04bcc068a44c5641c727883947960fb8dcbd5.1416319692.git.jslaby@suse.cz> References: <28f04bcc068a44c5641c727883947960fb8dcbd5.1416319692.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yu Zhao 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 5ddacbe92b806cd5b4f8f154e8e46ac267fff55c upstream. Compound page should be freed by put_page() or free_pages() with correct order. Not doing so will cause tail pages leaked. The compound order can be obtained by compound_order() or use HPAGE_PMD_ORDER in our case. Some people would argue the latter is faster but I prefer the former which is more general. This bug was observed not just on our servers (the worst case we saw is 11G leaked on a 48G machine) but also on our workstations running Ubuntu based distro. $ cat /proc/vmstat | grep thp_zero_page_alloc thp_zero_page_alloc 55 thp_zero_page_alloc_failed 0 This means there is (thp_zero_page_alloc - 1) * (2M - 4K) memory leaked. Fixes: 97ae17497e99 ("thp: implement refcounting for huge zero page") Signed-off-by: Yu Zhao Acked-by: Kirill A. Shutemov Cc: Andrea Arcangeli Cc: Mel Gorman Cc: David Rientjes Cc: Bob Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Jiri Slaby --- mm/huge_memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 10532dd43abc..e497843f5f65 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -192,7 +192,7 @@ retry: preempt_disable(); if (cmpxchg(&huge_zero_page, NULL, zero_page)) { preempt_enable(); - __free_page(zero_page); + __free_pages(zero_page, compound_order(zero_page)); goto retry; } @@ -224,7 +224,7 @@ static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { struct page *zero_page = xchg(&huge_zero_page, NULL); BUG_ON(zero_page == NULL); - __free_page(zero_page); + __free_pages(zero_page, compound_order(zero_page)); return HPAGE_PMD_NR; } -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/