From: Gavin Shan <shangw@linux.vnet.ibm.com>
To: hannes@cmpxchg.org
Cc: linux-mm@kvack.org
Subject: Re: [PATCH 2/2] MM: check limit while deallocating bootmem node
Date: Sat, 28 Apr 2012 10:00:11 +0800 [thread overview]
Message-ID: <20120428020011.GC8061@shangw> (raw)
In-Reply-To: <20120428013802.GA8061@shangw>
>Hi Johannes,
>
>Could you take a look on this while you have available time?
>
It's my bad. It should be this one:
[PATCH 1/2] MM: fixup on addition to bootmem data list
>Thanks,
>Gavin
>
>>For the particular bootmem node, the minimal and maximal PFN (
>>Page Frame Number) have been traced in the instance of "struct
>>bootmem_data_t". On current implementation, the maximal PFN isn't
>>checked while deallocating a bunch (BITS_PER_LONG) of page frames.
>>So the current implementation won't work if the maximal PFN isn't
>>aligned with BITS_PER_LONG.
>>
>>The patch will check the maximal PFN of the given bootmem node.
>>Also, we needn't check all the bits map when the starting PFN isn't
>>BITS_PER_LONG aligned. Actually, we should start from the offset
>>of the bits map, which indicated by the starting PFN.
>>
>>Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
>>---
>> mm/bootmem.c | 11 ++++++++---
>> 1 files changed, 8 insertions(+), 3 deletions(-)
>>
>>diff --git a/mm/bootmem.c b/mm/bootmem.c
>>index 5a04536..ebac3ba 100644
>>--- a/mm/bootmem.c
>>+++ b/mm/bootmem.c
>>@@ -194,16 +194,20 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
>> * BITS_PER_LONG block of pages in front of us, free
>> * it in one go.
>> */
>>- if (IS_ALIGNED(start, BITS_PER_LONG) && vec == ~0UL) {
>>+ if (end - start >= BITS_PER_LONG &&
>>+ IS_ALIGNED(start, BITS_PER_LONG) &&
>>+ vec == ~0UL) {
>> int order = ilog2(BITS_PER_LONG);
>>
>> __free_pages_bootmem(pfn_to_page(start), order);
>> count += BITS_PER_LONG;
>> start += BITS_PER_LONG;
>> } else {
>>- unsigned long off = 0;
>>+ unsigned long cursor = start;
>>+ unsigned long off = cursor & (BITS_PER_LONG - 1);
>>
>>- while (vec && off < BITS_PER_LONG) {
>>+ vec >>= off;
>>+ while (vec && off < BITS_PER_LONG && cursor < end) {
>> if (vec & 1) {
>> page = pfn_to_page(start + off);
>> __free_pages_bootmem(page, 0);
>>@@ -211,6 +215,7 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
>> }
>> vec >>= 1;
>> off++;
>>+ cursor++;
>> }
>> start = ALIGN(start + 1, BITS_PER_LONG);
>> }
>>--
>>1.7.5.4
>>
>
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next prev parent reply other threads:[~2012-04-28 2:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-27 3:41 [PATCH 1/2] MM: fixup on addition to bootmem data list Gavin Shan
2012-04-27 3:41 ` [PATCH 2/2] MM: check limit while deallocating bootmem node Gavin Shan
2012-04-27 23:27 ` Johannes Weiner
2012-04-28 1:58 ` Gavin Shan
2012-04-28 1:38 ` Gavin Shan
2012-04-28 2:00 ` Gavin Shan [this message]
2012-05-09 21:25 ` [PATCH 1/2] MM: fixup on addition to bootmem data list Johannes Weiner
2012-05-10 1:02 ` Gavin Shan
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