From: Pavel Machek <pavel@ucw.cz>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: paul.szabo@sydney.edu.au, 695182@bugs.debian.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC] Reproducible OOM with just a few sleeps
Date: Wed, 30 Jan 2013 13:51:51 +0100 [thread overview]
Message-ID: <20130130125151.GB19069@amd.pavel.ucw.cz> (raw)
In-Reply-To: <50F4A92F.2070204@linux.vnet.ibm.com>
Hi!
> > I understand that more RAM leaves less lowmem. What is unacceptable is
> > that PAE crashes or freezes with OOM: it should gracefully handle the
> > issue. Noting that (for a machine with 4GB or under) PAE fails where the
> > HIGHMEM4G kernel succeeds and survives.
>
> You have found a delta, but you're not really making apples-to-apples
> comparisons. The page tables (a huge consumer of lowmem in your bug
> reports) have much more overhead on a PAE kernel. A process with a
> single page faulted in with PAE will take at least 4 pagetable pages
> (it's 7 in practice for me with sleeps). It's 2 pages minimum (and in
> practice with sleeps) on HIGHMEM4G.
>
> There's probably a bug here. But, it's incredibly unlikely to be seen
> in practice on anything resembling a modern system. The 'sleep' issue
> is easily worked around by upgrading to a 64-bit kernel, or using
Are you saying that HIGHMEM configuration with 4GB ram is not expected
to work?
Pavel
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next prev parent reply other threads:[~2013-01-30 12:51 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-12 3:31 paul.szabo
2013-01-14 15:00 ` Dave Hansen
2013-01-14 20:36 ` paul.szabo
2013-01-15 0:34 ` Bug#695182: " Ben Hutchings
2013-01-15 0:56 ` Dave Hansen
2013-01-15 2:16 ` paul.szabo
2013-01-30 12:51 ` Pavel Machek [this message]
2013-01-30 15:32 ` Dave Hansen
2013-01-30 19:40 ` paul.szabo
2013-01-31 5:15 ` Bug#695182: " Ben Hutchings
2013-01-31 9:07 ` paul.szabo
2013-01-31 13:38 ` Ben Hutchings
2013-01-31 23:06 ` paul.szabo
2013-02-01 1:07 ` Ben Hutchings
2013-02-01 2:12 ` paul.szabo
2013-02-01 2:57 ` Ben Hutchings
2013-02-01 3:13 ` paul.szabo
2013-02-01 4:38 ` Phil Turmel
2013-02-01 10:20 ` Pavel Machek
2013-02-01 10:25 ` PAE problems was " Pavel Machek
2013-02-01 16:57 ` H. Peter Anvin
2013-02-01 17:45 ` Ben Hutchings
2013-02-07 0:28 ` Dave Hansen
2013-02-10 19:09 ` Pavel Machek
2013-02-17 9:10 ` Simon Jeons
2013-02-24 22:10 ` paul.szabo
2013-01-12 19:41 paul.szabo
2013-01-15 10:25 Sedat Dilek
2013-01-17 21:04 paul.szabo
2013-01-17 21:55 ` Dave Hansen
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