linux-kernel - Re: [PATCHv2, RFC 17/30] thp: wait_split_huge_page(): serialize over i_mmap

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: <514CA182.7050906@sr71.net>
Date:	Fri, 22 Mar 2013 11:22:58 -0700
From:	Dave <dave@...1.net>
To:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
CC:	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Hugh Dickins <hughd@...gle.com>,
	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 <matthew.r.wilcox@...el.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Hillf Danton <dhillf@...il.com>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2, RFC 17/30] thp: wait_split_huge_page(): serialize over
 i_mmap_mutex too

On 03/14/2013 10:50 AM, Kirill A. Shutemov wrote:
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -113,11 +113,20 @@ extern void __split_huge_page_pmd(struct vm_area_struct *vma,
>  			__split_huge_page_pmd(__vma, __address,		\
>  					____pmd);			\
>  	}  while (0)
> -#define wait_split_huge_page(__anon_vma, __pmd)				\
> +#define wait_split_huge_page(__vma, __pmd)				\
>  	do {								\
>  		pmd_t *____pmd = (__pmd);				\
> -		anon_vma_lock_write(__anon_vma);			\
> -		anon_vma_unlock_write(__anon_vma);			\
> +		struct address_space *__mapping =			\
> +					vma->vm_file->f_mapping;	\
> +		struct anon_vma *__anon_vma = (__vma)->anon_vma;	\
> +		if (__mapping)						\
> +			mutex_lock(&__mapping->i_mmap_mutex);		\
> +		if (__anon_vma) {					\
> +			anon_vma_lock_write(__anon_vma);		\
> +			anon_vma_unlock_write(__anon_vma);		\
> +		}							\
> +		if (__mapping)						\
> +			mutex_unlock(&__mapping->i_mmap_mutex);		\
>  		BUG_ON(pmd_trans_splitting(*____pmd) ||			\
>  		       pmd_trans_huge(*____pmd));			\
>  	} while (0)

That thing was pretty ugly _before_. :)  Any chance this can get turned
in to a function?

What's the deal with the i_mmap_mutex operation getting split up?  I'm
blanking on what kind of pages would have both anon_vmas and a valid
mapping.
--
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/