From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-f197.google.com (mail-qk1-f197.google.com [209.85.222.197]) by kanga.kvack.org (Postfix) with ESMTP id 473BD6B02F4 for ; Tue, 6 Nov 2018 04:36:51 -0500 (EST) Received: by mail-qk1-f197.google.com with SMTP id s123-v6so25522317qkf.12 for ; Tue, 06 Nov 2018 01:36:51 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id f23-v6si360876qkg.163.2018.11.06.01.36.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Nov 2018 01:36:50 -0800 (PST) Date: Tue, 6 Nov 2018 17:36:45 +0800 From: Baoquan He Subject: Re: [PATCH] mm, memory_hotplug: teach has_unmovable_pages about of LRU migrateable pages Message-ID: <20181106093645.GM27491@MiWiFi-R3L-srv> References: <20181105002009.GF27491@MiWiFi-R3L-srv> <20181105091407.GB4361@dhcp22.suse.cz> <20181105092851.GD4361@dhcp22.suse.cz> <20181105102520.GB22011@MiWiFi-R3L-srv> <20181105123837.GH4361@dhcp22.suse.cz> <20181105142308.GJ27491@MiWiFi-R3L-srv> <20181105171002.GO4361@dhcp22.suse.cz> <20181106002216.GK27491@MiWiFi-R3L-srv> <20181106082826.GC27423@dhcp22.suse.cz> <20181106091624.GL27491@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181106091624.GL27491@MiWiFi-R3L-srv> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , linux-mm@kvack.org, LKML , Stable tree On 11/06/18 at 05:16pm, Baoquan He wrote: > On 11/06/18 at 09:28am, Michal Hocko wrote: > > > > > > > It failed. Paste the log and patch diff here, please help check if I made > > > > > > > any mistake on manual code change. The log is at bottom. > > > > > > > > > > > > The retry patch is obviously still racy, it just makes the race window > > > > > > slightly smaller and I hoped it would catch most of those races but this > > > > > > is obviously not the case. > > > > > > > > > > > > I was thinking about your MIGRATE_MOVABLE check some more and I still do > > > > > > not like it much, we just change migrate type at many places and I have > > > > > > hard time to actually see this is always safe wrt. to what we need here. > > > > > > > > > > > > We should be able to restore the zone type check though. The > > > > > > primary problem fixed by 15c30bc09085 ("mm, memory_hotplug: make > > > > > > has_unmovable_pages more robust") was that early allocations made it to > > > > > > the zone_movable range. If we add the check _after_ the PageReserved() > > > > > > check then we should be able to rule all bootmem allocation out. > > > > > > > > > > > > So what about the following (on top of the previous patch which makes > > > > > > sense on its own I believe). > > > > > > > > > > Yes, I think this looks very reasonable and should be robust. > > > > > > > > > > Have tested it, hot removing 4 hotpluggable nodes continusously > > > > > succeeds, and then hot adding them back, still works well. > > > > > > > > > > So please feel free to add my Tested-by or Acked-by. > > > > > > > > > > Tested-by: Baoquan He > > > > > or > > > > > Acked-by: Baoquan He > > > > > > > > Thanks for retesting! Does this apply to both patches? > > > > > > Sorry, don't get it. I just applied this on top of linus's tree and > > > tested. Do you mean applying it on top of previous code change? > > > > Yes. While the first patch will obviously not help for movable zone > > because the movable check will override any later check it > > seems still useful to reduce false positives on normal zones. > > Hmm, I don't know if it will bring a little bit confusion on code > understanding. Since we only recognize the movable zone issue, and I can > only reproduce and verify it on the movable zone issue with the movable > zone check adding. > > Not sure if there are any scenario or use cases to cover those newly added > checking other movable zone checking. Surely, I have no objection to ^ than > adding them. But the two patches are separate issues, they have no > dependency on each other. > > I just tested the movable zone checking yesterday, will add your > previous check back, then test again. I believe the result will be > positive. Will udpate once done. > > Thanks > Baoquan