From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id 6E63D280256 for ; Thu, 29 Sep 2016 04:44:23 -0400 (EDT) Received: by mail-wm0-f69.google.com with SMTP id b4so6646394wmb.0 for ; Thu, 29 Sep 2016 01:44:23 -0700 (PDT) Received: from mail-wm0-f65.google.com (mail-wm0-f65.google.com. [74.125.82.65]) by mx.google.com with ESMTPS id i4si13525061wjv.214.2016.09.29.01.44.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Sep 2016 01:44:21 -0700 (PDT) Received: by mail-wm0-f65.google.com with SMTP id w84so9561203wmg.0 for ; Thu, 29 Sep 2016 01:44:21 -0700 (PDT) From: Michal Hocko Subject: [PATCH 2/2] mm: warn about allocations which stall for too long Date: Thu, 29 Sep 2016 10:44:07 +0200 Message-Id: <20160929084407.7004-3-mhocko@kernel.org> In-Reply-To: <20160929084407.7004-1-mhocko@kernel.org> References: <20160923081555.14645-1-mhocko@kernel.org> <20160929084407.7004-1-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Johannes Weiner , Mel Gorman , Tetsuo Handa , Dave Hansen , linux-mm@kvack.org, LKML , Michal Hocko From: Michal Hocko Currently we do warn only about allocation failures but small allocations are basically nofail and they might loop in the page allocator for a long time. Especially when the reclaim cannot make any progress - e.g. GFP_NOFS cannot invoke the oom killer and rely on a different context to make a forward progress in case there is a lot memory used by filesystems. Give us at least a clue when something like this happens and warn about allocations which take more than 10s. Print the basic allocation context information along with the cumulative time spent in the allocation as well as the allocation stack. Repeat the warning after every 10 seconds so that we know that the problem is permanent rather than ephemeral. Signed-off-by: Michal Hocko --- mm/page_alloc.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 969ffc97045b..73f60ad6315f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3495,6 +3495,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, enum compact_result compact_result; int compaction_retries = 0; int no_progress_loops = 0; + unsigned long alloc_start = jiffies; + unsigned int stall_timeout = 10 * HZ; /* * In the slowpath, we sanity check order to avoid ever trying to @@ -3650,6 +3652,14 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, if (order > PAGE_ALLOC_COSTLY_ORDER && !(gfp_mask & __GFP_REPEAT)) goto nopage; + /* Make sure we know about allocations which stall for too long */ + if (time_after(jiffies, alloc_start + stall_timeout)) { + warn_alloc(gfp_mask, + "page alloction stalls for %ums, order:%u\n", + jiffies_to_msecs(jiffies-alloc_start), order); + stall_timeout += 10 * HZ; + } + if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, did_some_progress > 0, &no_progress_loops)) goto retry; -- 2.9.3 -- 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