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From: Andrew Morton <akpm@linux-foundation.org>
To: Russ Anderson <rja@sgi.com>
Cc: Rafael Aquini <aquini@linux.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	linux-mm <linux-mm@kvack.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH] [BUGFIX] mm: hugepages can cause negative commitlimit
Date: Fri, 20 May 2011 13:04:11 -0700	[thread overview]
Message-ID: <20110520130411.d1e0baef.akpm@linux-foundation.org> (raw)
In-Reply-To: <20110519221101.GC19648@sgi.com>

On Thu, 19 May 2011 17:11:01 -0500
Russ Anderson <rja@sgi.com> wrote:

> OK, I see your point.  The root problem is hugepages allocated at boot are
> subtracted from totalram_pages but hugepages allocated at run time are not.
> Correct me if I've mistate it or are other conditions.
> 
> By "allocated at run time" I mean "echo 1 > /proc/sys/vm/nr_hugepages".
> That allocation will not change totalram_pages but will change
> hugetlb_total_pages().
> 
> How best to fix this inconsistency?  Should totalram_pages include or exclude
> hugepages?  What are the implications?

The problem is that hugetlb_total_pages() is trying to account for two
different things, while totalram_pages accounts for only one of those
things, yes?

One fix would be to stop accounting for huge pages in totalram_pages
altogether.  That might break other things so careful checking would be
needed.

Or we stop accounting for the boot-time allocated huge pages in
hugetlb_total_pages().  Split the two things apart altogether and
account for boot-time allocated and runtime-allocated pages separately.  This
souds saner to me - it reflects what's actually happening in the kernel.

WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Russ Anderson <rja@sgi.com>
Cc: Rafael Aquini <aquini@linux.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	linux-mm <linux-mm@kvack.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH] [BUGFIX] mm: hugepages can cause negative commitlimit
Date: Fri, 20 May 2011 13:04:11 -0700	[thread overview]
Message-ID: <20110520130411.d1e0baef.akpm@linux-foundation.org> (raw)
In-Reply-To: <20110519221101.GC19648@sgi.com>

On Thu, 19 May 2011 17:11:01 -0500
Russ Anderson <rja@sgi.com> wrote:

> OK, I see your point.  The root problem is hugepages allocated at boot are
> subtracted from totalram_pages but hugepages allocated at run time are not.
> Correct me if I've mistate it or are other conditions.
> 
> By "allocated at run time" I mean "echo 1 > /proc/sys/vm/nr_hugepages".
> That allocation will not change totalram_pages but will change
> hugetlb_total_pages().
> 
> How best to fix this inconsistency?  Should totalram_pages include or exclude
> hugepages?  What are the implications?

The problem is that hugetlb_total_pages() is trying to account for two
different things, while totalram_pages accounts for only one of those
things, yes?

One fix would be to stop accounting for huge pages in totalram_pages
altogether.  That might break other things so careful checking would be
needed.

Or we stop accounting for the boot-time allocated huge pages in
hugetlb_total_pages().  Split the two things apart altogether and
account for boot-time allocated and runtime-allocated pages separately.  This
souds saner to me - it reflects what's actually happening in the kernel.

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  reply	other threads:[~2011-05-20 20:04 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-18 15:34 [PATCH] [BUGFIX] mm: hugepages can cause negative commitlimit Russ Anderson
2011-05-18 15:34 ` Russ Anderson
2011-05-19  0:51 ` Rafael Aquini
2011-05-19  4:56   ` Russ Anderson
2011-05-19  4:56     ` Russ Anderson
2011-05-19 13:37     ` Rafael Aquini
2011-05-19 22:11       ` Russ Anderson
2011-05-19 22:11         ` Russ Anderson
2011-05-20 20:04         ` Andrew Morton [this message]
2011-05-20 20:04           ` Andrew Morton
2011-05-20 22:30           ` Rafael Aquini
2011-05-20 22:30             ` Rafael Aquini
2011-05-26 21:07             ` Rafael Aquini
2011-05-26 21:07               ` Rafael Aquini
2011-05-27 22:22               ` Russ Anderson
2011-05-27 22:22                 ` Russ Anderson
2011-06-02  4:08               ` Russ Anderson
2011-06-02  4:08                 ` Russ Anderson
2011-06-03  2:55                 ` [PATCH] mm: fix negative commitlimit when gigantic hugepages are allocated Rafael Aquini
2011-06-03  2:55                   ` Rafael Aquini
2011-06-03 12:07                   ` Russ Anderson
2011-06-03 12:07                     ` Russ Anderson
2011-06-09 23:44                   ` Andrew Morton
2011-06-09 23:44                     ` Andrew Morton
2011-06-13 21:11                     ` Rafael Aquini
2011-06-13 21:11                       ` Rafael Aquini
2011-06-13 21:31                       ` Andrew Morton
2011-06-13 21:31                         ` Andrew Morton
2011-06-03  3:08                 ` [PATCH] [BUGFIX] mm: hugepages can cause negative commitlimit Rafael Aquini
2011-06-03  3:08                   ` Rafael Aquini

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