From: Andrew Morton <akpm@osdl.org>
To: Timur Tabi <timur.tabi@ammasso.com>
Cc: roland@topspin.com, linux-kernel@vger.kernel.org
Subject: Re: Correct way to release get_user_pages()?
Date: Sun, 30 Jan 2005 02:10:17 -0800 [thread overview]
Message-ID: <20050130021017.7ef1c764.akpm@osdl.org> (raw)
In-Reply-To: <41FA7AE2.10209@ammasso.com>
Timur Tabi <timur.tabi@ammasso.com> wrote:
>
> Roland Dreier wrote:
>
> > Reading through the tree, I see that some callers of get_user_pages()
> > release the pages that they got via put_page(), and some callers use
> > page_cache_release(). Of course <linux/pagemap.h> has
> >
> > #define page_cache_release(page) put_page(page)
> >
> > so this is really not much of a difference, but I'd like to know which
> > is considered better style. Any opinions?
I guess we should only use page_cache_release() if the page is known to be
pagecache. In the case of get_user_pages() the page could of course be
anonymous in which case put_page is probably more appropriate. It's all a
bit of a mess and if we ever do end up having PAGE_CACHE_SIZE > PAGE_SIZE,
someone will have some work to do.
I suppose put_page() would be better for now.
> I've defined this function. I'm not sure if it really works, but it
> looks good.
>
> #include <linux/pagemap.h>
>
> void put_user_pages(int len, struct page **pages)
> {
> int i;
>
> for (i=0; i<len; i++) {
> if (!PageReserved(pages[i])) {
> SetPageDirty(pages[i]);
> }
> page_cache_release(pages[i]);
> }
> }
no... You should only dirty the page if it was modified, and then use
set_page_dirty() or set_page_dirty_lock().
See dio_bio_complete() for an example.
next prev parent reply other threads:[~2005-01-30 10:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-28 3:02 Correct way to release get_user_pages()? Roland Dreier
2005-01-28 17:48 ` Timur Tabi
2005-01-30 10:10 ` Andrew Morton [this message]
2005-01-31 15:51 ` Timur Tabi
2005-01-31 21:01 ` Andrew Morton
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