From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f176.google.com (mail-pd0-f176.google.com [209.85.192.176]) by kanga.kvack.org (Postfix) with ESMTP id 03BFF6B0038 for ; Sun, 23 Aug 2015 03:23:49 -0400 (EDT) Received: by pdob1 with SMTP id b1so41440352pdo.2 for ; Sun, 23 Aug 2015 00:23:48 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id ot10si21497757pdb.76.2015.08.23.00.23.47 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Sun, 23 Aug 2015 00:23:48 -0700 (PDT) Subject: [REPOST] [PATCH 2/2] mm: Fix potentially scheduling in GFP_ATOMIC allocations. From: Tetsuo Handa Message-Id: <201508231623.DED13020.tFOHFVFQOSOLMJ@I-love.SAKURA.ne.jp> Date: Sun, 23 Aug 2015 16:23:37 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@kernel.org, rientjes@google.com, hannes@cmpxchg.org Cc: linux-mm@kvack.org >>From 08a638e04351386ab03cd1223988ac7940d4d3aa Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Sat, 1 Aug 2015 22:46:12 +0900 Subject: [PATCH 2/2] mm: Fix potentially scheduling in GFP_ATOMIC allocations. Currently, if somebody does GFP_ATOMIC | __GFP_NOFAIL allocation, wait_iff_congested() might be called via __alloc_pages_high_priority() before reaching if (!wait) { WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL); goto nopage; } because gfp_to_alloc_flags() includes ALLOC_NO_WATERMARKS if TIF_MEMDIE was set. We need to check for __GFP_WAIT flag at __alloc_pages_high_priority() in order to make sure that we won't schedule. Signed-off-by: Tetsuo Handa --- mm/page_alloc.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 37a0390..f9f09fa 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2917,16 +2917,15 @@ __alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order, { struct page *page; - do { + for (;;) { page = get_page_from_freelist(gfp_mask, order, ALLOC_NO_WATERMARKS, ac); - if (!page && gfp_mask & __GFP_NOFAIL) - wait_iff_congested(ac->preferred_zone, BLK_RW_ASYNC, - HZ/50); - } while (!page && (gfp_mask & __GFP_NOFAIL)); - - return page; + if (page || (gfp_mask & (__GFP_NOFAIL | __GFP_WAIT)) != + (__GFP_NOFAIL | __GFP_WAIT)) + return page; + wait_iff_congested(ac->preferred_zone, BLK_RW_ASYNC, HZ/50); + } } static void wake_all_kswapds(unsigned int order, const struct alloc_context *ac) -- 1.8.3.1 -- 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