From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f46.google.com (mail-wm0-f46.google.com [74.125.82.46]) by kanga.kvack.org (Postfix) with ESMTP id DFE6582F64 for ; Fri, 30 Oct 2015 04:23:26 -0400 (EDT) Received: by wmeg8 with SMTP id g8so5944532wme.0 for ; Fri, 30 Oct 2015 01:23:26 -0700 (PDT) Received: from mail-wm0-f48.google.com (mail-wm0-f48.google.com. [74.125.82.48]) by mx.google.com with ESMTPS id fv6si7476789wjc.132.2015.10.30.01.23.25 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 30 Oct 2015 01:23:25 -0700 (PDT) Received: by wmeg8 with SMTP id g8so5956771wme.1 for ; Fri, 30 Oct 2015 01:23:25 -0700 (PDT) Date: Fri, 30 Oct 2015 09:23:23 +0100 From: Michal Hocko Subject: Re: [RFC 1/3] mm, oom: refactor oom detection Message-ID: <20151030082323.GB18429@dhcp22.suse.cz> References: <1446131835-3263-1-git-send-email-mhocko@kernel.org> <1446131835-3263-2-git-send-email-mhocko@kernel.org> <5632FEEF.2050709@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5632FEEF.2050709@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: Kamezawa Hiroyuki Cc: linux-mm@kvack.org, Andrew Morton , Linus Torvalds , Mel Gorman , Johannes Weiner , Rik van Riel , David Rientjes , Tetsuo Handa , LKML On Fri 30-10-15 14:23:59, KAMEZAWA Hiroyuki wrote: > On 2015/10/30 0:17, mhocko@kernel.org wrote: [...] > > @@ -3135,13 +3145,56 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > > if (gfp_mask & __GFP_NORETRY) > > goto noretry; > > > > - /* Keep reclaiming pages as long as there is reasonable progress */ > > + /* > > + * Do not retry high order allocations unless they are __GFP_REPEAT > > + * and even then do not retry endlessly. > > + */ > > pages_reclaimed += did_some_progress; > > - if ((did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER) || > > - ((gfp_mask & __GFP_REPEAT) && pages_reclaimed < (1 << order))) { > > - /* Wait for some write requests to complete then retry */ > > - wait_iff_congested(ac->preferred_zone, BLK_RW_ASYNC, HZ/50); > > - goto retry; > > + if (order > PAGE_ALLOC_COSTLY_ORDER) { > > + if (!(gfp_mask & __GFP_REPEAT) || pages_reclaimed >= (1< > + goto noretry; > > + > > + if (did_some_progress) > > + goto retry; > > why directly retry here ? Because I wanted to preserve the previous logic for GFP_REPEAT as much as possible here and do an incremental change in the later patch. [...] > > @@ -3150,8 +3203,10 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > > goto got_pg; > > > > /* Retry as long as the OOM killer is making progress */ > > - if (did_some_progress) > > + if (did_some_progress) { > > + stall_backoff = 0; > > goto retry; > > + } > > Umm ? I'm sorry that I didn't notice page allocation may fail even > if order < PAGE_ALLOC_COSTLY_ORDER. I thought old logic ignores > did_some_progress. It seems a big change. __alloc_pages_may_oom will set did_some_progress > So, now, 0-order page allocation may fail in a OOM situation ? No they don't normally and this patch doesn't change the logic here. -- Michal Hocko SUSE Labs -- 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