Re: [PATCH 2/2] MM: check limit while deallocating bootmem node

[Gavin Shan <shangw@linux.vnet.ibm.com>]

>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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