From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 845C2C61D97 for ; Wed, 22 Nov 2023 13:56:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343801AbjKVN4b (ORCPT ); Wed, 22 Nov 2023 08:56:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56408 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231613AbjKVN43 (ORCPT ); Wed, 22 Nov 2023 08:56:29 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B774B199 for ; Wed, 22 Nov 2023 05:56:25 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 7A1AE21979; Wed, 22 Nov 2023 13:56:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1700661384; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=4PL01vdipAxXI2et46ovWIE1C2j61g1DsIeVKK4hMJ8=; b=a8PFBE4bG4ry/xym88djaUEBZuMT6DkQChwAEsfDOWoIXWMauOOabCr1VcT2jZ/XMqyOrE 7fj98k6G520QLOvWtK0Dqur9JjfkfdgEXvKy4shV9GKRKT6ig2M2/f0SbhW4x0HUSmQryG wFVgLZoKlK6bFq7HzJJdpMEMVqVQLPk= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 524FF13467; Wed, 22 Nov 2023 13:56:24 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id qv2DEIgIXmWndwAAMHmgww (envelope-from ); Wed, 22 Nov 2023 13:56:24 +0000 Date: Wed, 22 Nov 2023 14:56:23 +0100 From: Michal Hocko To: Marcelo Tosatti Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Vlastimil Babka , Andrew Morton , David Hildenbrand , Peter Xu Subject: Re: [patch 0/2] mm: too_many_isolated can stall due to out of sync VM counters Message-ID: References: <20231113233420.446465795@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Authentication-Results: smtp-out1.suse.de; none X-Spamd-Result: default: False [-6.87 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; REPLY(-4.00)[]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; NEURAL_HAM_SHORT(-0.20)[-1.000]; RCPT_COUNT_SEVEN(0.00)[7]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-2.07)[95.48%] Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 22-11-23 08:26:02, Marcelo Tosatti wrote: [...] > Michal, > > Let me know if you have any objections to the patch, thanks. I do not think you have exaplained how the patch helps nor you have shown it has fixed the described problem. You seem to be very focused on the specific snapshot which I do agree shows that the data is out of sync and that there is throttling happening when strictly speaking it should noti. But (let me repeat) those discrepancies are so small that it is very likely that concurrent reclaimers will be stalled (just take one to isolate those pages) anyway. Maybe this leads to an earlier OOM killer invocation as untrottled reclaimers will be able to conclude there is no progress rather than being throttled on the direct reclaim. That being said I am not saying the patch is incorrect. Nevertheless, I do not think we want to merge this patch without a better understanding what is going on in your specific case and what kind of runtime difference does the patch make in that case. From your previous email it seems like the actual case is mostly memory stress test that manages to fill out the memory to push almost all the file LRU while anon LRU is not reclaimable for some reason. That shouldn't be terribly hard to reproduce. -- Michal Hocko SUSE Labs