From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f41.google.com (mail-pa0-f41.google.com [209.85.220.41]) by kanga.kvack.org (Postfix) with ESMTP id 5BFC66B006C for ; Tue, 2 Jun 2015 08:37:07 -0400 (EDT) Received: by padjw17 with SMTP id jw17so60285077pad.2 for ; Tue, 02 Jun 2015 05:37:07 -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 pr9si25901746pbc.12.2015.06.02.05.37.05 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 02 Jun 2015 05:37:06 -0700 (PDT) Received: from fsav305.sakura.ne.jp (fsav305.sakura.ne.jp [153.120.85.136]) by www262.sakura.ne.jp (8.14.5/8.14.5) with ESMTP id t52Cb34e046323 for ; Tue, 2 Jun 2015 21:37:03 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from AQUA (softbank126227184186.bbtec.net [126.227.184.186]) (authenticated bits=0) by www262.sakura.ne.jp (8.14.5/8.14.5) with ESMTP id t52Cb3Nd046320 for ; Tue, 2 Jun 2015 21:37:03 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Subject: [PATCH] mm: Fix theoretical sleeping in atomic. From: Tetsuo Handa Message-Id: <201506022137.FEE05202.FSHtJOVFQFOLOM@I-love.SAKURA.ne.jp> Date: Tue, 2 Jun 2015 21:37:01 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org >>From 7e4775600798d24680ff449412f2d0479711948c Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Tue, 2 Jun 2015 21:14:28 +0900 Subject: [PATCH] mm: Fix theoretical sleeping in atomic. We could theoretically be too late to warn on (gfp_mask & (__GFP_NOFAIL | __GFP_WAIT)) == __GFP_NOFAIL if get_page_from_freelist(ALLOC_NO_WATERMARKS) failed at __alloc_pages_high_priority(), for wait_iff_congested() in __alloc_pages_high_priority() might have already slept for kmalloc(GFP_ATOMIC | __GFP_NOFAIL) allocation request because ALLOC_NO_WATERMARKS can be automatically supplied due to e.g. TIF_MEMDIE. Make sure that __alloc_pages_high_priority() will not loop unless both __GFP_NOFAIL and __GFP_WAIT are given. Maybe if (!wait) WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL); part should be moved to immediately after if (order >= MAX_ORDER) { WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN)); return NULL; } ? 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 73aa335..187a0b5 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2880,16 +2880,15 @@ __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