Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031164AbbD1WkM (ORCPT ); Tue, 28 Apr 2015 18:40:12 -0400 Received: from mail-ig0-f173.google.com ([209.85.213.173]:37591 "EHLO mail-ig0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031054AbbD1WkH (ORCPT ); Tue, 28 Apr 2015 18:40:07 -0400 Date: Tue, 28 Apr 2015 15:40:05 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Johannes Weiner cc: Andrew Morton , Michal Hocko , Tetsuo Handa , Andrea Arcangeli , Dave Chinner , Vlastimil Babka , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/9] mm: oom_kill: generalize OOM progress waitqueue In-Reply-To: <1430161555-6058-5-git-send-email-hannes@cmpxchg.org> Message-ID: References: <1430161555-6058-1-git-send-email-hannes@cmpxchg.org> <1430161555-6058-5-git-send-email-hannes@cmpxchg.org> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1246 Lines: 28 On Mon, 27 Apr 2015, Johannes Weiner wrote: > It turns out that the mechanism to wait for exiting OOM victims is > less generic than it looks: it won't issue wakeups unless the OOM > killer is disabled. > > The reason this check was added was the thought that, since only the > OOM disabling code would wait on this queue, wakeup operations could > be saved when that specific consumer is known to be absent. > > However, this is quite the handgrenade. Later attempts to reuse the > waitqueue for other purposes will lead to completely unexpected bugs > and the failure mode will appear seemingly illogical. Generally, > providers shouldn't make unnecessary assumptions about consumers. > > This could have been replaced with waitqueue_active(), but it only > saves a few instructions in one of the coldest paths in the kernel. > Simply remove it. > > Signed-off-by: Johannes Weiner > Acked-by: Michal Hocko Acked-by: David Rientjes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/