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: <Ycx2b8yla4VzeWWs@localhost.localdomain>
Date:   Wed, 29 Dec 2021 15:53:35 +0100
From:   Oscar Salvador <osalvador@...e.de>
To:     Chen Wandun <chenwandun@...wei.com>
Cc:     akpm@...ux-foundation.org, vbabka@...e.cz, iamjoonsoo.kim@....com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        wangkefeng.wang@...wei.com
Subject: Re: [PATCH] mm/page_isolation: unset migratetype directly for non
 Buddy page

On Wed, Dec 29, 2021 at 11:36:49AM +0800, Chen Wandun wrote:
> There is no need to try to move_freepages_block for pages that is not
> in buddy in function unset_migratetype_isolate, it can directly set
> migrate type.

The above could benefit from some rephrasing, someting along these lines
maybe?

"In unset_migratetype_isolate(), we can bypass the call to
move_freepages_block() for non-buddy pages"

> 
> It will save a few cpu cycles for some situations such as cma and
> hugetlb when allocating continue pages, in these situation function
> alloc_contig_pages will be called.
> 
> alloc_contig_pages
> 	__alloc_contig_migrate_range
> 	isolate_freepages_range ==> pages has been remove from buddy
> 	undo_isolate_page_range
> 		unset_migratetype_isolate ==> can directly set migratetype
> 
> Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
> Signed-off-by: Chen Wandun <chenwandun@...wei.com>

I am ok with the "fix", but I don't think this deserves a Fixes tag.
Sure, it can spare some cpu cycles, but besides that, there is no harm
in the actual code unless I missed something.

Others might feel stronger about that.

Reviewed-by: Oscar Salvador <osalvador@...e.de>


-- 
Oscar Salvador
SUSE Labs

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ