From: Mel Gorman <mgorman@suse.de>
To: Kautuk Consul <consul.kautuk@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org
Subject: Re: [PATCH] ARM: sparsemem: Enable CONFIG_HOLES_IN_ZONE config option for SparseMem and HAS_HOLES_MEMORYMODEL for linux-3.0.
Date: Wed, 3 Aug 2011 12:05:55 +0100 [thread overview]
Message-ID: <20110803110555.GD19099@suse.de> (raw)
In-Reply-To: <CAFPAmTQByL0YJT8Lvar1Oe+3Q1EREvqPA_GP=hHApJDz5dSOzQ@mail.gmail.com>
On Tue, Aug 02, 2011 at 05:38:31PM +0530, Kautuk Consul wrote:
> Hi,
>
> In the case where the total kernel memory is not aligned to the
> SECTION_SIZE_BITS I see a kernel crash.
>
> When I copy a huge file, then the kernel crashes at the following callstack:
>
The callstack should not be 80-column formatted as this is completely
manged and unreadable without manual editting. Also, why did you not
include the full error message? With it, I'd have a better idea of
which bug check you hit.
> Backtrace:
> <SNIP>
>
> The reason for this is that the CONFIG_HOLES_IN_ZONE configuration
> option is not automatically enabled when SPARSEMEM or
> ARCH_HAS_HOLES_MEMORYMODEL are enabled. Due to this, the
> pfn_valid_within() macro always returns 1 due to which the BUG_ON is
> encountered.
> This patch enables the CONFIG_HOLES_IN_ZONE config option if either
> ARCH_HAS_HOLES_MEMORYMODEL or SPARSEMEM is enabled.
>
> Although I tested this on an older kernel, i.e., 2.6.35.13, I see that
> this option has not been enabled as yet in linux-3.0 and this appears
> to be a
> logically correct change anyways with respect to pfn_valid_within()
> functionality.
>
There is a performance cost associated with HOLES_IN_ZONE which may be
offset by memory savings but not necessarily.
If the BUG_ON you are hitting is this one
BUG_ON(page_zone(start_page) != page_zone(end_page)) then I'd be
wondering why the check in move_freepages_block() was insufficient.
If it's because holes are punched in the memmap then the option does
need to be set.
--
Mel Gorman
SUSE Labs
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WARNING: multiple messages have this Message-ID (diff)
From: mgorman@suse.de (Mel Gorman)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: sparsemem: Enable CONFIG_HOLES_IN_ZONE config option for SparseMem and HAS_HOLES_MEMORYMODEL for linux-3.0.
Date: Wed, 3 Aug 2011 12:05:55 +0100 [thread overview]
Message-ID: <20110803110555.GD19099@suse.de> (raw)
In-Reply-To: <CAFPAmTQByL0YJT8Lvar1Oe+3Q1EREvqPA_GP=hHApJDz5dSOzQ@mail.gmail.com>
On Tue, Aug 02, 2011 at 05:38:31PM +0530, Kautuk Consul wrote:
> Hi,
>
> In the case where the total kernel memory is not aligned to the
> SECTION_SIZE_BITS I see a kernel crash.
>
> When I copy a huge file, then the kernel crashes at the following callstack:
>
The callstack should not be 80-column formatted as this is completely
manged and unreadable without manual editting. Also, why did you not
include the full error message? With it, I'd have a better idea of
which bug check you hit.
> Backtrace:
> <SNIP>
>
> The reason for this is that the CONFIG_HOLES_IN_ZONE configuration
> option is not automatically enabled when SPARSEMEM or
> ARCH_HAS_HOLES_MEMORYMODEL are enabled. Due to this, the
> pfn_valid_within() macro always returns 1 due to which the BUG_ON is
> encountered.
> This patch enables the CONFIG_HOLES_IN_ZONE config option if either
> ARCH_HAS_HOLES_MEMORYMODEL or SPARSEMEM is enabled.
>
> Although I tested this on an older kernel, i.e., 2.6.35.13, I see that
> this option has not been enabled as yet in linux-3.0 and this appears
> to be a
> logically correct change anyways with respect to pfn_valid_within()
> functionality.
>
There is a performance cost associated with HOLES_IN_ZONE which may be
offset by memory savings but not necessarily.
If the BUG_ON you are hitting is this one
BUG_ON(page_zone(start_page) != page_zone(end_page)) then I'd be
wondering why the check in move_freepages_block() was insufficient.
If it's because holes are punched in the memmap then the option does
need to be set.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2011-08-03 11:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-02 12:08 [PATCH] ARM: sparsemem: Enable CONFIG_HOLES_IN_ZONE config option for SparseMem and HAS_HOLES_MEMORYMODEL for linux-3.0 Kautuk Consul
2011-08-02 12:08 ` Kautuk Consul
2011-08-03 11:05 ` Mel Gorman [this message]
2011-08-03 11:05 ` Mel Gorman
2011-08-03 12:29 ` Kautuk Consul
2011-08-03 12:29 ` Kautuk Consul
2011-08-03 13:28 ` Mel Gorman
2011-08-03 13:28 ` Mel Gorman
2011-08-04 9:36 ` Kautuk Consul
2011-08-04 9:36 ` Kautuk Consul
2011-08-04 10:09 ` Mel Gorman
2011-08-04 10:09 ` Mel Gorman
2011-08-05 5:57 ` Kautuk Consul
2011-08-05 5:57 ` Kautuk Consul
2011-08-05 8:47 ` Mel Gorman
2011-08-05 8:47 ` Mel Gorman
2011-08-05 11:40 ` Kautuk Consul
2011-08-05 11:40 ` Kautuk Consul
2011-08-24 12:31 ` Kautuk Consul
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