From: Benjamin LaHaise <bcrl@kvack.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kent Overstreet <kmo@daterainc.com>,
Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>, Christoph Lameter <cl@gentwo.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: bad page state in 3.13-rc4
Date: Thu, 19 Dec 2013 14:53:52 -0500 [thread overview]
Message-ID: <20131219195352.GB9228@kvack.org> (raw)
In-Reply-To: <CA+55aFz=tEkVAx9VndtCXApDxcw+5T-BxMsVuXp+vMSb05f8Aw@mail.gmail.com>
On Fri, Dec 20, 2013 at 04:45:38AM +0900, Linus Torvalds wrote:
> On Fri, Dec 20, 2013 at 4:26 AM, Benjamin LaHaise <bcrl@kvack.org> wrote:
> >
> > Okay, I'll rewriting it to use truncate to free the pages.
>
> It already does that in put_aio_ring_file() afaik. No?
Yes, that's what I found when I started looking into this in detail again.
I think the page reference counting is actually correct. There are 2
references on each page: the first is from the find_or_create_page() call,
and the second is from the get_user_pages() (which also makes sure the page
is populated into the page tables). The only place I can see things going
off the rails is if the get_user_pages() call fails. It's possible trinity
could be arranging things so that the get_user_pages() call is failing
somehow. Also, if it were a double free of a page, we should at least get
a VM_BUG() occuring when the page's count is 0.
Dave -- do you have CONFIG_DEBUG_VM on in your test rig?
> Linus
--
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next prev parent reply other threads:[~2013-12-19 19:53 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-19 4:07 bad page state in 3.13-rc4 Dave Jones
2013-12-19 4:40 ` Linus Torvalds
2013-12-19 15:41 ` Christoph Lameter
2013-12-19 20:11 ` Mel Gorman
2013-12-19 20:30 ` Dave Jones
2013-12-19 15:53 ` Dave Jones
2013-12-19 17:07 ` Linus Torvalds
2013-12-19 17:17 ` Dave Jones
2013-12-19 18:11 ` Kent Overstreet
2013-12-19 18:29 ` Benjamin LaHaise
2013-12-19 18:35 ` Dave Jones
2013-12-19 19:19 ` Linus Torvalds
2013-12-19 19:26 ` Benjamin LaHaise
2013-12-19 19:45 ` Linus Torvalds
2013-12-19 19:53 ` Benjamin LaHaise [this message]
2013-12-19 20:02 ` Linus Torvalds
2013-12-19 20:11 ` Linus Torvalds
2013-12-19 20:31 ` Benjamin LaHaise
2013-12-19 20:31 ` Linus Torvalds
2013-12-19 20:42 ` Benjamin LaHaise
2013-12-19 20:24 ` Dave Jones
2013-12-19 23:38 ` Benjamin LaHaise
2013-12-20 1:00 ` Dave Jones
2013-12-21 23:06 ` [PATCHes - aio / migrate page, please review] " Benjamin LaHaise
2013-12-22 19:09 ` Linus Torvalds
2013-12-22 21:30 ` Dave Jones
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