linux-kernel - Re: [PATCHv6 06/37] thp: handle write-protection faults for file THP

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Message-ID: <20170126155709.GA11239@node.shutemov.name>
Date:   Thu, 26 Jan 2017 18:57:09 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        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 06/37] thp: handle write-protection faults for file THP

On Thu, Jan 26, 2017 at 07:44:39AM -0800, Matthew Wilcox wrote:
> On Thu, Jan 26, 2017 at 02:57:48PM +0300, Kirill A. Shutemov wrote:
> > For filesystems that wants to be write-notified (has mkwrite), we will
> > encount write-protection faults for huge PMDs in shared mappings.
> > 
> > The easiest way to handle them is to clear the PMD and let it refault as
> > wriable.
> 
> ... of course, the filesystem could implement ->pmd_fault, and then it
> wouldn't hit this case ...

I would rather get rid of ->pmd_fault/->huge_fault :)

->fault should be flexible enough to provide for all of them...

-- 
 Kirill A. Shutemov