Re: Infinite looping observed in __offline_pages
From: Aneesh Kumar K.V
Date: Wed Aug 22 2018 - 23:01:51 EST
On 08/23/2018 12:28 AM, Mike Kravetz wrote:
On 08/22/2018 02:30 AM, Aneesh Kumar K.V wrote:
commit 2e9d754ac211f2af3731f15df3cd8cd070b4cc54
Author: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Date: Tue Aug 21 14:17:55 2018 +0530
mm/hugetlb: filter out hugetlb pages if HUGEPAGE migration is not supported.
When scanning for movable pages, filter out Hugetlb pages if hugepage migration
is not supported. Without this we hit infinte loop in __offline pages where we
do
pfn = scan_movable_pages(start_pfn, end_pfn);
if (pfn) { /* We have movable pages */
ret = do_migrate_range(pfn, end_pfn);
goto repeat;
}
We do support hugetlb migration ony if the hugetlb pages are at pmd level. Here
I thought migration at pgd level was added for POWER? commit 94310cbcaa3c
(mm/madvise: enable (soft|hard) offline of HugeTLB pages at PGD level).
Only remember, because I did not fully understand the use case. :)
yes. We hit the issue on older distro kernels.
we just check for Kernel config. The gigantic page size check is done in
page_huge_active.
Reported-by: Haren Myneni <haren@xxxxxxxxxxxxxxxxxx>
CC: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 4eb6e824a80c..f9bdea685cf4 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1338,7 +1338,8 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
return pfn;
if (__PageMovable(page))
return pfn;
- if (PageHuge(page)) {
+ if (IS_ENABLED(CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION) &&
+ PageHuge(page)) {
How about using hugepage_migration_supported instead? It would automatically
catch those non-migratable huge page sizes. Something like:
Will do that.
if (PageHuge(page) &&
hugepage_migration_supported(page_hstate(page))) {
-aneesh