From: Grygorii Strashko <grygorii.strashko@ti.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-arm-kernel@lists.infradead.org,
Yinghai Lu <yinghai@kernel.org>, Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH v3 02/23] mm/memblock: debug: don't free reserved array if !ARCH_DISCARD_MEMBLOCK
Date: Tue, 10 Dec 2013 18:44:15 +0200 [thread overview]
Message-ID: <52A744DF.7060005@ti.com> (raw)
In-Reply-To: <20131209161134.e161ddfedf284f2052cad4a5@linux-foundation.org>
Hi Andrew,
On 12/10/2013 02:11 AM, Andrew Morton wrote:
> On Mon, 9 Dec 2013 16:50:35 -0500 Santosh Shilimkar <santosh.shilimkar@ti.com> wrote:
>
>> Now the Nobootmem allocator will always try to free memory allocated for
>> reserved memory regions (free_low_memory_core_early()) without taking
>> into to account current memblock debugging configuration
>> (CONFIG_ARCH_DISCARD_MEMBLOCK and CONFIG_DEBUG_FS state).
>> As result if:
>> - CONFIG_DEBUG_FS defined
>> - CONFIG_ARCH_DISCARD_MEMBLOCK not defined;
>> - reserved memory regions array have been resized during boot
>>
>> then:
>> - memory allocated for reserved memory regions array will be freed to
>> buddy allocator;
>> - debug_fs entry "sys/kernel/debug/memblock/reserved" will show garbage
>> instead of state of memory reservations. like:
>> 0: 0x98393bc0..0x9a393bbf
>> 1: 0xff120000..0xff11ffff
>> 2: 0x00000000..0xffffffff
>>
>> Hence, do not free memory allocated for reserved memory regions if
>> defined(CONFIG_DEBUG_FS) && !defined(CONFIG_ARCH_DISCARD_MEMBLOCK).
>
> Alternatives:
>
> - disable /proc/sys/kernel/debug/memblock/reserved in this case
>
> - disable defined(CONFIG_DEBUG_FS) &&
> !defined(CONFIG_ARCH_DISCARD_MEMBLOCK) in Kconfig.
Yes. But this is debug information and it's useful to have it.
>
> How much memory are we talking about here? If it's more than "very
> little" then I think either of these would be better - most users will
> value the extra memory over an accurate
> /proc/sys/kernel/debug/memblock/reserved?
>
Sorry, I have no real statistic information and I hit this issue while testing this series
by simulating huge amount of bootmem allocation during kernel boot.
The real number of entries i saw on Keystone & OMAP boards is no more than ~20.
Few digits below:
- size of static reserved memory regions array is 2048 bytes
- the size of array is doubled during each allocation
Regards,
-grygorii
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next prev parent reply other threads:[~2013-12-10 15:46 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-09 21:50 [PATCH v3 00/23] mm: Use memblock interface instead of bootmem Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 01/23] mm/memblock: debug: correct displaying of upper memory boundary Santosh Shilimkar
2013-12-09 21:56 ` Felipe Balbi
2013-12-09 22:39 ` Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 02/23] mm/memblock: debug: don't free reserved array if !ARCH_DISCARD_MEMBLOCK Santosh Shilimkar
2013-12-10 0:11 ` Andrew Morton
2013-12-10 16:44 ` Grygorii Strashko [this message]
2013-12-09 21:50 ` [PATCH v3 03/23] mm/bootmem: remove duplicated declaration of __free_pages_bootmem() Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 04/23] mm/memblock: remove unnecessary inclusions of bootmem.h Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 05/23] mm/memblock: drop WARN and use SMP_CACHE_BYTES as a default alignment Santosh Shilimkar
2013-12-13 21:21 ` Tejun Heo
2013-12-09 21:50 ` [PATCH v3 06/23] mm/memblock: reorder parameters of memblock_find_in_range_node Santosh Shilimkar
2013-12-13 21:22 ` Tejun Heo
2013-12-09 21:50 ` [PATCH v3 07/23] mm/memblock: switch to use NUMA_NO_NODE instead of MAX_NUMNODES Santosh Shilimkar
2013-12-13 21:29 ` Tejun Heo
2013-12-14 0:44 ` Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 08/23] mm/memblock: Add memblock memory allocation apis Santosh Shilimkar
2013-12-10 0:25 ` Andrew Morton
2013-12-10 16:04 ` Santosh Shilimkar
2013-12-13 21:37 ` Tejun Heo
2013-12-14 0:52 ` Santosh Shilimkar
2013-12-14 11:08 ` Tejun Heo
2013-12-14 19:48 ` Santosh Shilimkar
2013-12-20 22:30 ` Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 09/23] mm/init: Use memblock apis for early memory allocations Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 10/23] mm/printk: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 11/23] mm/page_alloc: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 12/23] mm/power: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 13/23] mm/lib/swiotlb: " Santosh Shilimkar
2013-12-13 1:08 ` Andrew Morton
2013-12-13 1:24 ` Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 14/23] mm/lib/cpumask: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 15/23] mm/sparse: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 16/23] mm/hugetlb: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 17/23] mm/page_cgroup: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 18/23] mm/percpu: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 19/23] mm/memory_hotplug: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 20/23] mm/firmware: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 21/23] mm/ARM: kernel: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 22/23] mm/ARM: mm: " Santosh Shilimkar
2013-12-09 21:50 ` [PATCH v3 23/23] mm/ARM: OMAP: " Santosh Shilimkar
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