From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f200.google.com (mail-wj0-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id 7805F6B026D for ; Wed, 18 Jan 2017 09:11:38 -0500 (EST) Received: by mail-wj0-f200.google.com with SMTP id gt1so2730296wjc.0 for ; Wed, 18 Jan 2017 06:11:38 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u73si433223wrc.271.2017.01.18.06.11.36 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 18 Jan 2017 06:11:37 -0800 (PST) From: Vlastimil Babka Subject: [PATCH] mm/mempolicy.c: do not put mempolicy before using its nodemask Date: Wed, 18 Jan 2017 15:11:24 +0100 Message-Id: <20170118141124.8345-1-vbabka@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , stable@vger.kernel.org, "Aneesh Kumar K . V" , "Kirill A . Shutemov" , David Rientjes , Andrea Arcangeli Since commit be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma") alloc_pages_vma() can potentially free a mempolicy by mpol_cond_put() before accessing the embedded nodemask by __alloc_pages_nodemask(). The commit log says it's so "we can use a single exit path within the function" but that's clearly wrong. We can still do that when doing mpol_cond_put() after the allocation attempt. Make sure the mempolicy is not freed prematurely, otherwise __alloc_pages_nodemask() can end up using a bogus nodemask, which could lead e.g. to premature OOM. Fixes: be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma") Signed-off-by: Vlastimil Babka Cc: stable@vger.kernel.org Cc: Aneesh Kumar K.V Cc: Kirill A. Shutemov Cc: David Rientjes Cc: Andrea Arcangeli --- mm/mempolicy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 2e346645eb80..1e7873e40c9a 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2017,8 +2017,8 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma, nmask = policy_nodemask(gfp, pol); zl = policy_zonelist(gfp, pol, node); - mpol_cond_put(pol); page = __alloc_pages_nodemask(gfp, order, zl, nmask); + mpol_cond_put(pol); out: if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) goto retry_cpuset; -- 2.11.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org