From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 538636B0069 for ; Mon, 2 Oct 2017 10:44:52 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id e69so8810822pfg.1 for ; Mon, 02 Oct 2017 07:44:52 -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 7si8592067ple.699.2017.10.02.07.44.50 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 02 Oct 2017 07:44:51 -0700 (PDT) Subject: Re: [RFC] [PATCH] mm,oom: Offload OOM notify callback to a kernel thread. From: Tetsuo Handa References: <20171002115035.7sph6ul6hsszdwa4@dhcp22.suse.cz> <201710022205.IGD04659.HSOMJFFQtFOLOV@I-love.SAKURA.ne.jp> <20171002131330.5c5mpephrosfuxsa@dhcp22.suse.cz> <201710022252.DDJ51535.JFQSLFHFVOtOOM@I-love.SAKURA.ne.jp> <20171002171641-mutt-send-email-mst@kernel.org> In-Reply-To: <20171002171641-mutt-send-email-mst@kernel.org> Message-Id: <201710022344.JII17368.HQtLOMJOOSFFVF@I-love.SAKURA.ne.jp> Date: Mon, 2 Oct 2017 23:44:45 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: mst@redhat.com Cc: mhocko@kernel.org, linux-mm@kvack.org Michael S. Tsirkin wrote: > > Yes, conditional GFP_KERNEL allocation attempt from virtqueue_add() might > > still cause this deadlock. But that depends on whether you can trigger this > > deadlock. As far as I know, there is no report. Thus, I think that avoiding > > theoretical deadlock using timeout will be sufficient. > > > So first of all IMHO GFP_KERNEL allocations do not happen in > virtqueue_add_outbuf at all. They only trigger through add_sgs. I did not notice that total_sg == 1 is true for virtqueue_add_outbuf(). > > IMHO this is an API bug, we should just drop the gfp parameter > from this API. OK. > > > so the issue is balloon_page_enqueue only. > Since you explained that there is "the deflate on OOM flag", we don't want to skip deflating upon lock contention. -- 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