linux-kernel - Re: [PATCHv4 23/39] thp: wait_split_huge_page(): serialize over i_mmap

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Date:	Mon,  3 Jun 2013 19:09:20 +0300 (EEST)
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Dave Hansen <dave@...1.net>
Cc:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	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: [PATCHv4 23/39] thp: wait_split_huge_page(): serialize over
 i_mmap_mutex too

Dave Hansen wrote:
> 
> On 06/03/2013 08:02 AM, Kirill A. Shutemov wrote:
> > Dave Hansen wrote:
> >> On 05/11/2013 06:23 PM, Kirill A. Shutemov wrote:
> >>> From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com
> >>> -#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)
> ...
> >> Could you also describe the lengths to which you've gone to try and keep
> >> this macro from growing in to any larger of an abomination.  Is it truly
> >> _impossible_ to turn this in to a normal function?  Or will it simply be
> >> a larger amount of work that you can do right now?  What would it take?
> > 
> > Okay, I've tried once again. The patch is below. It looks too invasive for
> > me. What do you think?
> 
> That patch looks great to me, actually.  It really looks to just be
> superficially moving code around.  The diffstat is even too:

One of blocker I see is new dependency <linux/mm.h> -> <linux/fs.h>.
It makes header files nightmare worse.

-- 
 Kirill A. Shutemov
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