On Tue, Dec 10, 2013 at 05:45:07PM +0900, Joonsoo Kim wrote:
>On Tue, Dec 10, 2013 at 10:17:56AM +0800, Wanpeng Li wrote:
>> Hi Joonsoo,
>> On Mon, Dec 09, 2013 at 06:10:43PM +0900, Joonsoo Kim wrote:
>> >We should remove the page from the list if we fail without ENOSYS,
>> >since migrate_pages() consider error cases except -ENOMEM and -EAGAIN
>> >as permanent failure and it assumes that the page would be removed from
>> >the list. Without this patch, we could overcount number of failure.
>> >
>> >In addition, we should put back the new hugepage if
>> >!hugepage_migration_support(). If not, we would leak hugepage memory.
>> >
>> >Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>> >
>> >diff --git a/mm/migrate.c b/mm/migrate.c
>> >index c6ac87a..b1cfd01 100644
>> >--- a/mm/migrate.c
>> >+++ b/mm/migrate.c
>> >@@ -1011,7 +1011,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>> > {
>> > int rc = 0;
>> > int *result = NULL;
>> >- struct page *new_hpage = get_new_page(hpage, private, &result);
>> >+ struct page *new_hpage;
>> > struct anon_vma *anon_vma = NULL;
>> >
>> > /*
>> >@@ -1021,9 +1021,12 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>> > * tables or check whether the hugepage is pmd-based or not before
>> > * kicking migration.
>> > */
>> >- if (!hugepage_migration_support(page_hstate(hpage)))
>> >+ if (!hugepage_migration_support(page_hstate(hpage))) {
>> >+ putback_active_hugepage(hpage);
>> > return -ENOSYS;
>>
>> The memory hotplug(do_migrate_range) and hwpoison(soft_offline_huge_page) callsets both
>> will call putback_movable_pages/putback_active_hugepage for -ENOSYS case.
>
>Hello Wanpeng.
>
>Yes, those callsite handle error case, but error case handling should be done
>in unmap_and_move_huge_page(). It is mentioned on patch 1. If we defer to
>remove the pages from the list, nr_failed can be overcounted.
>
I see.
Reviewed-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
>Thanks.
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