linux-kernel - Re: [PATCH, RFC 06/16] thp, mm: rewrite add_to_page_cache

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Message-ID: <5107c525eb8d1_f167d78c8425f9@blue.mail>
Date:	Tue, 29 Jan 2013 14:48:37 +0200
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Hillf Danton <dhillf@...il.com>,
	"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>,
	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>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH, RFC 06/16] thp, mm: rewrite add_to_page_cache_locked() to
 support huge pages

Hillf Danton wrote:
> On Mon, Jan 28, 2013 at 5:24 PM, Kirill A. Shutemov
> <kirill.shutemov@...ux.intel.com> wrote:
> > +       page_cache_get(page);
> > +       spin_lock_irq(&mapping->tree_lock);
> > +       page->mapping = mapping;
> > +       if (PageTransHuge(page)) {
> > +               int i;
> > +               for (i = 0; i < HPAGE_CACHE_NR; i++) {
> > +                       page_cache_get(page + i);
> > +                       page[i].index = offset + i;
> > +                       error = radix_tree_insert(&mapping->page_tree,
> > +                                       offset + i, page + i);
> > +                       if (error) {
> > +                               page_cache_release(page + i);
> > +                               break;
> > +                       }
> 
> Is page count balanced with the following?

It's broken. Last minue changes are evil :(

Thanks for catching it. I'll fix it in next revision.

> @@ -168,6 +180,9 @@ void delete_from_page_cache(struct page *page)
> 
>         if (freepage)
>                 freepage(page);
> +       if (PageTransHuge(page))
> +               for (i = 1; i < HPAGE_CACHE_NR; i++)
> +                       page_cache_release(page);
>         page_cache_release(page);

-- 
 Kirill A. Shutemov
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