From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 6 Nov 2018 08:22:16 +0800 From: Baoquan He To: Michal Hocko Cc: Andrew Morton , linux-mm@kvack.org, LKML , Stable tree Subject: Re: [PATCH] mm, memory_hotplug: teach has_unmovable_pages about of LRU migrateable pages Message-ID: <20181106002216.GK27491@MiWiFi-R3L-srv> References: <20181101091055.GA15166@MiWiFi-R3L-srv> <20181102155528.20358-1-mhocko@kernel.org> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181105171002.GO4361@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: On 11/05/18 at 06:10pm, Michal Hocko wrote: > On Mon 05-11-18 22:23:08, Baoquan He wrote: > > On 11/05/18 at 01:38pm, Michal Hocko wrote: > > > On Mon 05-11-18 18:25:20, Baoquan He wrote: > > > > Hi Michal, > > > > > > > > On 11/05/18 at 10:28am, Michal Hocko wrote: > > > > > > > > > > Or something like this. Ugly as hell, no question about that. I also > > > > > have to think about this some more to convince myself this will not > > > > > result in an endless loop under some situations. > > > > > > > > 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?