linux-kernel - Re: [PATCH 07/12] mm, thp, tmpfs: handle huge page in shmem_undo

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] [day] [month] [year] [list]

Message-ID: <CACz4_2eR+-N+FmOj+JB0YXKNZZpOaP7JG79rCr=xFKKLp4y7fw@mail.gmail.com>
Date:	Thu, 17 Oct 2013 13:58:35 -0700
From:	Ning Qu <quning@...gle.com>
To:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Wu Fengguang <fengguang.wu@...el.com>, Jan Kara <jack@...e.cz>,
	Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
	Andi Kleen <ak@...ux.intel.com>,
	Matthew Wilcox <willy@...ux.intel.com>,
	Hillf Danton <dhillf@...il.com>, Dave Hansen <dave@...1.net>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 07/12] mm, thp, tmpfs: handle huge page in
 shmem_undo_range for truncate

Best wishes,
-- 
Ning Qu (曲宁) | Software Engineer | quning@...gle.com | +1-408-418-6066


On Wed, Oct 16, 2013 at 5:09 AM, Kirill A. Shutemov
<kirill.shutemov@...ux.intel.com> wrote:
> Ning Qu wrote:
>> > Again. Here and below ifdef is redundant: PageTransHugeCache() is zero
>> > compile-time and  thp case will be optimize out.
>>
>> The problem is actually from HPAGE_CACHE_INDEX_MASK, it is marked as
>> build bug when CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE is false. So we
>> either wrap some logic inside a inline function, or we have to be like
>> this .. Or we don't treat the HPAGE_CACHE_INDEX_MASK as a build bug?
>
> HPAGE_CACHE_INDEX_MASK shouldn't be a problem.
> If it's wrapped into 'if PageTransHugeCache(page)' or similar it will be
> eliminated by compiler if thp-pc disabled and build bug will not be
> triggered.
>
>>
>> >
>> > And do we really need a copy of truncate logic here? Is there a way to
>> > share code?
>> >
>> The truncate between tmpfs and general one is similar but not exactly
>> the same (no readahead), so share the whole function might not be a
>> good choice from the perspective of tmpfs? Anyway, there are other
>> similar functions in tmpfs, e.g. the one you mentioned for
>> shmem_add_to_page_cache. It is possible to share the code, I am just
>> worried it will make the logic more complicated?
>
> I think introducing thp-pc is good opportunity to refactor all these code.

I agree, I review the code of generate truncate and shmem_undo_range again.
There are just too many differences in almost every major piece of
logic. It's really
not possible to extract any meaningful common function to share between them.

And I agree, we will try to refactor any other functions which are
possible. Thanks!

>
> --
>  Kirill A. Shutemov
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/