Re: Infinite looping observed in __offline_pages
From: Mike Kravetz <hidden>
Date: 2018-08-22 19:01:21
Also in:
lkml
On 08/22/2018 02:30 AM, Aneesh Kumar K.V wrote:
commit 2e9d754ac211f2af3731f15df3cd8cd070b4cc54
Author: Aneesh Kumar K.V [off-list ref]
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. HereI 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. :)
quoted hunk ↗ jump to hunk
we just check for Kernel config. The gigantic page size check is done in page_huge_active. Reported-by: Haren Myneni [off-list ref] CC: Naoya Horiguchi [off-list ref] Signed-off-by: Aneesh Kumar K.V [off-list ref]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:
if (PageHuge(page) &&
hugepage_migration_supported(page_hstate(page))) {
--
Mike Kravetz
quoted hunk ↗ jump to hunk
if (page_huge_active(page)) return pfn; elsediff --git a/mm/page_alloc.c b/mm/page_alloc.c index 15ea511fb41c..a3f81e18c882 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c@@ -7649,6 +7649,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, * handle each tail page individually in migration. */ if (PageHuge(page)) { + + if (!IS_ENABLED(CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION)) + goto unmovable; + iter = round_up(iter + 1, 1<<compound_order(page)) - 1; continue; }