From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id A57737F63 for ; Tue, 20 May 2014 01:30:44 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay2.corp.sgi.com (Postfix) with ESMTP id 7C5AC30407F for ; Mon, 19 May 2014 23:30:41 -0700 (PDT) Received: from ipmail07.adl2.internode.on.net (ipmail07.adl2.internode.on.net [150.101.137.131]) by cuda.sgi.com with ESMTP id w4FHGUXSSyuUZDKF for ; Mon, 19 May 2014 23:30:39 -0700 (PDT) Date: Tue, 20 May 2014 16:30:24 +1000 From: Dave Chinner Subject: Re: [PATCH] mm/vmscan: Do not block forever at shrink_inactive_list(). Message-ID: <20140520063024.GH18954@dastard> References: <201405192340.FCD48964.OFQHOOJLVSFFMt@I-love.SAKURA.ne.jp> <20140520004449.GE18954@dastard> <20140519225915.3370328d.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20140519225915.3370328d.akpm@linux-foundation.org> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Andrew Morton Cc: riel@redhat.com, Tetsuo Handa , linux-kernel@vger.kernel.org, xfs@oss.sgi.com, kosaki.motohiro@jp.fujitsu.com, fengguang.wu@intel.com, kamezawa.hiroyu@jp.fujitsu.com On Mon, May 19, 2014 at 10:59:15PM -0700, Andrew Morton wrote: > On Tue, 20 May 2014 10:44:49 +1000 Dave Chinner wrote: > > > @@ -258,14 +258,23 @@ xfs_bmapi_allocate_worker( > > struct xfs_bmalloca *args = container_of(work, > > struct xfs_bmalloca, work); > > unsigned long pflags; > > + unsigned long new_pflags = PF_FSTRANS; > > > > - /* we are in a transaction context here */ > > - current_set_flags_nested(&pflags, PF_FSTRANS); > > + /* > > + * we are in a transaction context here, but may also be doing work > > + * in kswapd context, and hence we may need to inherit that state > > + * temporarily to ensure that we don't block waiting for memory reclaim > > + * in any way. > > + */ > > + if (args->kswapd) > > + new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; > > So current_is_kswapd() returns true for a thread which is not kswapd. > That's a bit smelly. > > Should this thread really be incrementing KSWAPD_INODESTEAL instead of > PGINODESTEAL, for example? current_is_kswapd() does a range of things, > only one(?) of which you actually want. It's doing work on behalf of kswapd under kswapd constraints, so it should both behave and be accounted as if kswapd was executing the work directly. > It would be cleaner to create a new PF_ flag to select just that > behavior. That's a better model than telling the world "I am magic and > special". However, it is magic and special because of who the work needs to be done for. > But we're awfully close to running out of PF_ space and I don't know if > this ugly justifies consuming a flag. I don't really care enough argue over what mechanism should be used. I'll push this patch through the XFS tree, and when a new flag or generic mechanism for pushing task contexts to kworker threads is provided, I'll change the XFS code to use that.... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs