linux-kernel - [x86_64] "bad pmd" when using huge pages

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Message-ID: <4CFD8DD9.1000101@infoblox.com>
Date:	Mon, 6 Dec 2010 17:28:57 -0800
From:	Kin Cho <kcho@...oblox.com>
To:	<linux-kernel@...r.kernel.org>
Subject: [x86_64] "bad pmd" when using huge pages

Hi,

With a stock 2.6.32-8 kernel (with minor patches) configured for
x86_64 and using huge pages, I'm seeing dmesg output like this:

mm/memory.c:144: bad pmd ffff880117bb6128(00000002cca000e7).

At this point one huge page is apparently "leaked" --
h->free_huge_pages in gather_surplus_pages is 1 less, until rebooted.

When this happens, the system is moderately loaded (~70% idle).

Also, if processes (bdb) holding shared (huge) pages are not
restarted, or when configured for x86, the problem doesn't appear.

Looking at the pmd flags, the problem appears to be related to the
_PAGE_PSE bit incorrectly getting set.

Any suggestions/comments is appreciated.

Thanks,

-kin

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