From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH RFC] memcg: close the race window between OOM detection and killing Date: Sat, 6 Jun 2015 09:56:06 +0900 Message-ID: <20150606005606.GA12744@mtj.duckdns.org> References: <20150603031544.GC7579@mtj.duckdns.org> <20150603144414.GG16201@dhcp22.suse.cz> <20150603193639.GH20091@mtj.duckdns.org> <20150604093031.GB4806@dhcp22.suse.cz> <20150604192936.GR20091@mtj.duckdns.org> <20150605143534.GD26113@dhcp22.suse.cz> <20150605145759.GA5946@mtj.duckdns.org> <20150605152135.GE26113@dhcp22.suse.cz> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=40MUFnrZ8D5ybWhxLboVJGcs0k5SFDj28gu+AxPS/o8=; b=UNSJbvl0uV3OY53zNNNgvqF+DHSwRr7F84uHMe+sU+cDaspGUpeuEMv9qimwXaGj4d AHCdD+uRoi5ZtChBmRJYRZ24d2INaEuX/LWbucdlhjY7u7xYMqpe5U7nhLdfsZkGSIZb w3ydhivzZTDh9LuhBddVOv5wNY2H7S3Byxtfg/Jqkq3+BrB4L1QyD6LvPyGglWB4n0QI 2+2+GbcdHJu4XqpqJPvVqTrNsPB9NXwHozed1On+2+CCdFojEmuCvCkGi3XbQHg0sSu+ 78JTxArZd/xZfBY4/9tgZVbpUkkVYJb9j7FXEkwYMLGWMMUyt1TXaFG1+OWCptVkyRq6 R7GQ== Content-Disposition: inline In-Reply-To: <20150605152135.GE26113@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michal Hocko Cc: Johannes Weiner , cgroups@vger.kernel.org, linux-mm@kvack.org Hello, Michal. On Fri, Jun 05, 2015 at 05:21:35PM +0200, Michal Hocko wrote: ... > > > TIF_MEMDIE but the allocation path hasn't noticed that because it's passed > > > /* > > > * Go through the zonelist yet one more time, keep very high watermark > > > * here, this is only to catch a parallel oom killing, we must fail if > > > * we're still under heavy pressure. > > > */ > > > page = get_page_from_freelist(gfp_mask | __GFP_HARDWALL, order, > > > ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac); > > > > > > and goes on to kill another task because there is no TIF_MEMDIE > > > anymore. > > > > Why would this be an issue if we disallow parallel killing? > > I am confused. The whole thread has started by fixing a race in memcg > and I was asking about the global case which is racy currently as well. Ah, okay, I thought we were still talking about issues w/ making things synchronous, but anyways, the above isn't a synchronization race per-se which is what the original patch was trying to address for memcg OOM path, right? Thanks. -- tejun -- 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