From: Andrew Morton <akpm@linux-foundation.org>
To: aquini@linux.com
Cc: Russ Anderson <rja@sgi.com>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-mm <linux-mm@kvack.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Christoph Lameter <cl@linux.com>,
rja@americas.sgi.com
Subject: Re: [PATCH] mm: fix negative commitlimit when gigantic hugepages are allocated
Date: Thu, 9 Jun 2011 16:44:08 -0700 [thread overview]
Message-ID: <20110609164408.8370746e.akpm@linux-foundation.org> (raw)
In-Reply-To: <20110603025555.GA10530@optiplex.tchesoft.com>
On Thu, 2 Jun 2011 23:55:57 -0300
Rafael Aquini <aquini@linux.com> wrote:
> When 1GB hugepages are allocated on a system, free(1) reports
> less available memory than what really is installed in the box.
> Also, if the total size of hugepages allocated on a system is
> over half of the total memory size, CommitLimit becomes
> a negative number.
>
> The problem is that gigantic hugepages (order > MAX_ORDER)
> can only be allocated at boot with bootmem, thus its frames
> are not accounted to 'totalram_pages'. However, they are
> accounted to hugetlb_total_pages()
>
> What happens to turn CommitLimit into a negative number
> is this calculation, in fs/proc/meminfo.c:
>
> allowed = ((totalram_pages - hugetlb_total_pages())
> * sysctl_overcommit_ratio / 100) + total_swap_pages;
>
> A similar calculation occurs in __vm_enough_memory() in mm/mmap.c.
>
> Also, every vm statistic which depends on 'totalram_pages' will render
> confusing values, as if system were 'missing' some part of its memory.
Is this bug serious enough to justify backporting the fix into -stable
kernels?
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: aquini@linux.com
Cc: Russ Anderson <rja@sgi.com>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-mm <linux-mm@kvack.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Christoph Lameter <cl@linux.com>,
rja@americas.sgi.com
Subject: Re: [PATCH] mm: fix negative commitlimit when gigantic hugepages are allocated
Date: Thu, 9 Jun 2011 16:44:08 -0700 [thread overview]
Message-ID: <20110609164408.8370746e.akpm@linux-foundation.org> (raw)
In-Reply-To: <20110603025555.GA10530@optiplex.tchesoft.com>
On Thu, 2 Jun 2011 23:55:57 -0300
Rafael Aquini <aquini@linux.com> wrote:
> When 1GB hugepages are allocated on a system, free(1) reports
> less available memory than what really is installed in the box.
> Also, if the total size of hugepages allocated on a system is
> over half of the total memory size, CommitLimit becomes
> a negative number.
>
> The problem is that gigantic hugepages (order > MAX_ORDER)
> can only be allocated at boot with bootmem, thus its frames
> are not accounted to 'totalram_pages'. However, they are
> accounted to hugetlb_total_pages()
>
> What happens to turn CommitLimit into a negative number
> is this calculation, in fs/proc/meminfo.c:
>
> allowed = ((totalram_pages - hugetlb_total_pages())
> * sysctl_overcommit_ratio / 100) + total_swap_pages;
>
> A similar calculation occurs in __vm_enough_memory() in mm/mmap.c.
>
> Also, every vm statistic which depends on 'totalram_pages' will render
> confusing values, as if system were 'missing' some part of its memory.
Is this bug serious enough to justify backporting the fix into -stable
kernels?
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next prev parent reply other threads:[~2011-06-09 23:44 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
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 [this message]
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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