From: Andrew Morton <akpm@linux-foundation.org>
To: linux-mm@kvack.org, netdev@vger.kernel.org
Cc: bugme-daemon@bugzilla.kernel.org, starlight@binnacle.cx,
Rafael Aquini <aquini@linux.com>
Subject: Re: [Bugme-new] [Bug 38032] New: default values of /proc/sys/net/ipv4/udp_mem does not consider huge page allocatio
Date: Wed, 6 Jul 2011 16:03:18 -0700 [thread overview]
Message-ID: <20110706160318.2c604ae9.akpm@linux-foundation.org> (raw)
In-Reply-To: <bug-38032-10286@https.bugzilla.kernel.org/>
(switched to email. Please respond via emailed reply-to-all, not via the
bugzilla web interface).
(cc's added)
On Tue, 21 Jun 2011 00:35:22 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=38032
>
> Summary: default values of /proc/sys/net/ipv4/udp_mem does not
> consider huge page allocatio
> Product: Memory Management
> Version: 2.5
> Platform: All
> OS/Version: Linux
> Tree: Mainline
> Status: NEW
> Severity: normal
> Priority: P1
> Component: Other
> AssignedTo: akpm@linux-foundation.org
> ReportedBy: starlight@binnacle.cx
> Regression: No
>
>
> In the RHEL 5.5 back-port of this tunable we ran into trouble locking up
> systems because the boot-time default is set based on physical memory does not
> account for the hugepages= in the boot parameters. So the UDP socket buffer
> limit can exceed phyisical memory. Don't know if this is an issue in mainline
> kernels but it seems likely so reporting this as a courtsey. Seems like it
> would be easy to fix the default to account for the memory reserved by
> hugepages which is not available for slab allocations.
>
> https://bugzilla.redhat.com/show_bug.cgi?id=714833
>
Yes, we've made similar mistakes in other places.
I don't think we really have an official formula for what callers
should be doing here. net/ipv4/udp.c:udp_init() does
nr_pages = totalram_pages - totalhigh_pages;
which assumes that totalram_pages does not include the pages which were
lost to hugepage allocations.
I *think* that this is now the case, but it wasn't always the case - we
made relatively recent fixes to the totalram_pages maintenance.
Perhaps UDP should be using the misnamed nr_free_buffer_pages() here.
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next parent reply other threads:[~2011-07-06 23:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-38032-10286@https.bugzilla.kernel.org/>
2011-07-06 23:03 ` Andrew Morton [this message]
2011-07-07 1:31 ` [Bugme-new] [Bug 38032] New: default values of /proc/sys/net/ipv4/udp_mem does not consider huge page allocation starlight
2011-07-07 3:59 ` Eric Dumazet
2011-07-07 4:38 ` Eric Dumazet
2011-07-07 7:27 ` David Miller
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