linux-kernel - Re: bad page state in 3.13-rc4

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Message-ID: <20131219202416.GA14519@redhat.com>
Date:	Thu, 19 Dec 2013 15:24:16 -0500
From:	Dave Jones <davej@...hat.com>
To:	Benjamin LaHaise <bcrl@...ck.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Kent Overstreet <kmo@...erainc.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>, Christoph Lameter <cl@...two.org>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: bad page state in 3.13-rc4

On Thu, Dec 19, 2013 at 02:53:52PM -0500, Benjamin LaHaise wrote:

 > 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?

Yes. Note the original trace in this thread was a VM_BUG_ON(atomic_read(&page->_count) <= 0);

Right after these crashes btw, the box locks up solid. So bad that traces don't
always make it over usb-serial. Annoying.

	Dave


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