linux-kernel - Re: [PATCH] mm,page_alloc,cma: conditionally prefer cma pageblocks for movable allocations

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200311173526.GH96999@carbon.dhcp.thefacebook.com>
Date:   Wed, 11 Mar 2020 10:35:26 -0700
From:   Roman Gushchin <guro@...com>
To:     Vlastimil Babka <vbabka@...e.cz>
CC:     Rik van Riel <riel@...riel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <kernel-team@...com>, Qian Cai <cai@....pw>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH] mm,page_alloc,cma: conditionally prefer cma pageblocks
 for movable allocations

On Wed, Mar 11, 2020 at 09:51:07AM +0100, Vlastimil Babka wrote:
> On 3/6/20 9:01 PM, Rik van Riel wrote:
> > Posting this one for Roman so I can deal with any upstream feedback and
> > create a v2 if needed, while scratching my head over the next piece of
> > this puzzle :)
> > 
> > ---8<---
> > 
> > From: Roman Gushchin <guro@...com>
> > 
> > Currently a cma area is barely used by the page allocator because
> > it's used only as a fallback from movable, however kswapd tries
> > hard to make sure that the fallback path isn't used.
> 
> Few years ago Joonsoo wanted to fix these kinds of weird MIGRATE_CMA corner
> cases by using ZONE_MOVABLE instead [1]. Unfortunately it was reverted due to
> unresolved bugs. Perhaps the idea could be resurrected now?

Hi Vlastimil!

Thank you for this reminder! I actually looked at it and also asked Joonsoo in private
about the state of this patch(set). As I understand, Joonsoo plans to resubmit
it later this year.

What Rik and I are suggesting seems to be much simpler, however it's perfectly
possible that Joonsoo's solution is preferable long-term.

So if the proposed patch looks ok for now, I'd suggest to go with it and return
to this question once we'll have a new version of ZONE_MOVABLE solution.

Thanks!