On 2022/5/11 15:07, Rei Yamamoto wrote:
> On Wed, 11 May 2022 14:25:34 Miaohe Lin wrote:
>> On 2022/5/11 12:43, Rei Yamamoto wrote:
>>> Prevent returning a pfn outside the target zone in case that not
>>> aligned with pageblock boundary.
>>> Otherwise isolate_migratepages_block() would handle pages not in
>>> the target zone.
>>>
>>
>> IIUC, the sole caller isolate_migratepages will ensure the pfn won't outside
>> the target zone. So the below code change might not be necessary. Or am I miss
>> something ?
>
> While block_start_pfn is ensured, this variable is not used as the argument for
> isolate_migratepages_block():
> -----
> static isolate_migrate_t isolate_migratepages(struct compact_control *cc)
> {
> :
> low_pfn = fast_find_migrateblock(cc);
> block_start_pfn = pageblock_start_pfn(low_pfn);
> if (block_start_pfn < cc->zone->zone_start_pfn)
> block_start_pfn = cc->zone->zone_start_pfn; <--- block_start_pfn is ensured not outside
> the target zone
> :
> block_end_pfn = pageblock_end_pfn(low_pfn);
> :
> for (; block_end_pfn <= cc->free_pfn;
> fast_find_block = false,
> cc->migrate_pfn = low_pfn = block_end_pfn,
> block_start_pfn = block_end_pfn,
> block_end_pfn += pageblock_nr_pages) {
> :
> if (isolate_migratepages_block(cc, low_pfn, block_end_pfn, <--- low_pfn is passed as
> the argument
Sorry, I think you're right. And could you please add the runtime effect of this issue?
Anyway, this patch looks good to me now. Thanks!
Reviewed-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> isolate_mode))
> return ISOLATE_ABORT;
> -----
>
> So, the low_pfn passed to isolate_migratepages_block() can be outside the target zone.
>
> Thanks,
> Rei
> .
>
