linux-kernel - Re: [PATCHv6 15/37] thp: do not threat slab pages as huge in hpage_{nr

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: <20170210221357.GF2267@bombadil.infradead.org>
Date:   Fri, 10 Feb 2017 14:13:57 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Theodore Ts'o <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Hugh Dickins <hughd@...gle.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-block@...r.kernel.org
Subject: Re: [PATCHv6 15/37] thp: do not threat slab pages as huge in
 hpage_{nr_pages,size,mask}

On Thu, Jan 26, 2017 at 02:57:57PM +0300, Kirill A. Shutemov wrote:
> Slab pages can be compound, but we shouldn't threat them as THP for
> pupose of hpage_* helpers, otherwise it would lead to confusing results.
> 
> For instance, ext4 uses slab pages for journal pages and we shouldn't
> confuse them with THPs. The easiest way is to exclude them in hpage_*
> helpers.

Well ... I think we should just deal with compound pages instead of just
huge or regular.  So I'm deferring comment on this patch.

> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
>  include/linux/huge_mm.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index e5c9c26d2439..5e6c408f5b47 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -137,21 +137,21 @@ static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
>  }
>  static inline int hpage_nr_pages(struct page *page)
>  {
> -	if (unlikely(PageTransHuge(page)))
> +	if (unlikely(!PageSlab(page) && PageTransHuge(page)))
>  		return HPAGE_PMD_NR;
>  	return 1;
>  }
>  
>  static inline int hpage_size(struct page *page)
>  {
> -	if (unlikely(PageTransHuge(page)))
> +	if (unlikely(!PageSlab(page) && PageTransHuge(page)))
>  		return HPAGE_PMD_SIZE;
>  	return PAGE_SIZE;
>  }
>  
>  static inline unsigned long hpage_mask(struct page *page)
>  {
> -	if (unlikely(PageTransHuge(page)))
> +	if (unlikely(!PageSlab(page) && PageTransHuge(page)))
>  		return HPAGE_PMD_MASK;
>  	return PAGE_MASK;
>  }
> -- 
> 2.11.0
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html