| Message ID | 20180824063314.21981-1-aneesh.kumar@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/hugetlb: filter out hugetlb pages if HUGEPAGE migration is not supported. | expand |
On Fri 24-08-18 12:03:14, Aneesh Kumar K.V wrote: > 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 > we just check for Kernel config. The gigantic page size check is done in > page_huge_active. Well, this is a bit misleading. I would say that Fix this by checking hugepage_migration_supported both in has_unmovable_pages which is the primary backoff mechanism for page offlining and for consistency reasons also into scan_movable_pages because it doesn't make any sense to return a pfn to non-migrateable huge page. > Acked-by: Michal Hocko <mhocko@suse.com> > Reported-by: Haren Myneni <haren@linux.vnet.ibm.com> > CC: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> I would add Fixes: 72b39cfc4d75 ("mm, memory_hotplug: do not fail offlining too early") Not because the bug has been introduced by that commit but rather because the issue would be latent before that commit. My Acked-by still holds. > --- > mm/memory_hotplug.c | 3 ++- > mm/page_alloc.c | 4 ++++ > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 9eea6e809a4e..38d94b703e9d 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1333,7 +1333,8 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > if (__PageMovable(page)) > return pfn; > if (PageHuge(page)) { > - if (page_huge_active(page)) > + if (hugepage_migration_supported(page_hstate(page)) && > + page_huge_active(page)) > return pfn; > else > pfn = round_up(pfn + 1, > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index c677c1506d73..b8d91f59b836 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7709,6 +7709,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, > * handle each tail page individually in migration. > */ > if (PageHuge(page)) { > + > + if (!hugepage_migration_supported(page_hstate(page))) > + goto unmovable; > + > iter = round_up(iter + 1, 1<<compound_order(page)) - 1; > continue; > } > -- > 2.17.1
On Fri, Aug 24, 2018 at 09:58:15AM +0200, Michal Hocko wrote: > On Fri 24-08-18 12:03:14, Aneesh Kumar K.V wrote: > > 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 > > we just check for Kernel config. The gigantic page size check is done in > > page_huge_active. > > Well, this is a bit misleading. I would say that > > Fix this by checking hugepage_migration_supported both in has_unmovable_pages > which is the primary backoff mechanism for page offlining and for > consistency reasons also into scan_movable_pages because it doesn't make > any sense to return a pfn to non-migrateable huge page. > > > Acked-by: Michal Hocko <mhocko@suse.com> > > Reported-by: Haren Myneni <haren@linux.vnet.ibm.com> > > CC: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > > I would add > Fixes: 72b39cfc4d75 ("mm, memory_hotplug: do not fail offlining too early") > > Not because the bug has been introduced by that commit but rather > because the issue would be latent before that commit. > > My Acked-by still holds. Looks good to me (with Michal's update on description). Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > > --- > > mm/memory_hotplug.c | 3 ++- > > mm/page_alloc.c | 4 ++++ > > 2 files changed, 6 insertions(+), 1 deletion(-) > > > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > > index 9eea6e809a4e..38d94b703e9d 100644 > > --- a/mm/memory_hotplug.c > > +++ b/mm/memory_hotplug.c > > @@ -1333,7 +1333,8 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > > if (__PageMovable(page)) > > return pfn; > > if (PageHuge(page)) { > > - if (page_huge_active(page)) > > + if (hugepage_migration_supported(page_hstate(page)) && > > + page_huge_active(page)) > > return pfn; > > else > > pfn = round_up(pfn + 1, > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index c677c1506d73..b8d91f59b836 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -7709,6 +7709,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, > > * handle each tail page individually in migration. > > */ > > if (PageHuge(page)) { > > + > > + if (!hugepage_migration_supported(page_hstate(page))) > > + goto unmovable; > > + > > iter = round_up(iter + 1, 1<<compound_order(page)) - 1; > > continue; > > } > > -- > > 2.17.1 > > -- > Michal Hocko > SUSE Labs >
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 9eea6e809a4e..38d94b703e9d 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1333,7 +1333,8 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end) if (__PageMovable(page)) return pfn; if (PageHuge(page)) { - if (page_huge_active(page)) + if (hugepage_migration_supported(page_hstate(page)) && + page_huge_active(page)) return pfn; else pfn = round_up(pfn + 1, diff --git a/mm/page_alloc.c b/mm/page_alloc.c index c677c1506d73..b8d91f59b836 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7709,6 +7709,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, * handle each tail page individually in migration. */ if (PageHuge(page)) { + + if (!hugepage_migration_supported(page_hstate(page))) + goto unmovable; + iter = round_up(iter + 1, 1<<compound_order(page)) - 1; continue; }
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 we just check for Kernel config. The gigantic page size check is done in page_huge_active. Acked-by: Michal Hocko <mhocko@suse.com> Reported-by: Haren Myneni <haren@linux.vnet.ibm.com> CC: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> --- mm/memory_hotplug.c | 3 ++- mm/page_alloc.c | 4 ++++ 2 files changed, 6 insertions(+), 1 deletion(-)