From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id D5C7A6B02F4 for ; Fri, 1 Sep 2017 08:55:28 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id 136so184910wmm.4 for ; Fri, 01 Sep 2017 05:55:28 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id b13si76264wrh.252.2017.09.01.05.55.27 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 01 Sep 2017 05:55:27 -0700 (PDT) Date: Fri, 1 Sep 2017 14:55:24 +0200 From: Michal Hocko Subject: Re: [PATCH 1/2] mm,page_alloc: don't call __node_reclaim() without scoped allocation constraints. Message-ID: <20170901125524.p3xtglunuufgfqcq@dhcp22.suse.cz> References: <1504269608-9202-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1504269608-9202-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Rientjes , Mel Gorman , Vlastimil Babka On Fri 01-09-17 21:40:07, Tetsuo Handa wrote: > We are doing the first allocation attempt before calling > current_gfp_context(). But since slab shrinker functions might depend on > __GFP_FS and/or __GFP_IO masking, calling slab shrinker functions from > node_reclaim() from get_page_from_freelist() without calling > current_gfp_context() has possibility of deadlock. Therefore, make sure > that the first memory allocation attempt does not call slab shrinker > functions. But we do filter gfp_mask at __node_reclaim layer. Not really ideal from the readability point of view and maybe it could be cleaned up there shouldn't be any bug AFAICS. On the other hand we can save few cycles on the hot path that way and there are people who care about every cycle there and node reclaim is absolutely the last thing they care about. -- 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