On Thu 19-10-17 14:21:18, Michal Hocko wrote: [...] > From 8cbd811d741f5dd93d1b21bb3ef94482a4d0bd32 Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@xxxxxxxx> > Date: Thu, 19 Oct 2017 14:14:02 +0200 > Subject: [PATCH] mm: distinguish CMA and MOVABLE isolation in > has_unmovable_pages > > Joonsoo has noticed that "mm: drop migrate type checks from > has_unmovable_pages" would break CMA allocator because it relies on > has_unmovable_pages returning false even for CMA pageblocks which in > fact don't have to be movable: > alloc_contig_range > start_isolate_page_range > set_migratetype_isolate > has_unmovable_pages > > This is a result of the code sharing between CMA and memory hotplug > while each one has a different idea of what has_unmovable_pages should > return. This is unfortunate but fixing it properly would require a lot > of code duplication. > > Fix the issue by introducing the requested migrate type argument > and special case MIGRATE_CMA case where CMA page blocks are handled > properly. This will work for memory hotplug because it requires > MIGRATE_MOVABLE. > > Reported-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> > --- Andrew, could you add this one to the bundle as well? After mm-drop-migrate-type-checks-from-has_unmovable_pages.patch, please. Joonsoo would like to see a larger change in this area [1] but I think we need to think those much more through [2] and Joonsoo agreed to take the simpler patch first [3]. Thanks! [1] http://lkml.kernel.org/r/20171024044423.GA31424@js1304-P5Q-DELUXE [2] http://lkml.kernel.org/r/20171024122526.3kmabkcbmj4johli@xxxxxxxxxxxxxx [3] http://lkml.kernel.org/r/20171026024707.GA11791@js1304-P5Q-DELUXE > include/linux/page-isolation.h | 2 +- > mm/page_alloc.c | 12 +++++++++++- > mm/page_isolation.c | 10 +++++----- > 3 files changed, 17 insertions(+), 7 deletions(-) > > diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h > index d4cd2014fa6f..fa9db0c7b54e 100644 > --- a/include/linux/page-isolation.h > +++ b/include/linux/page-isolation.h > @@ -30,7 +30,7 @@ static inline bool is_migrate_isolate(int migratetype) > #endif > > bool has_unmovable_pages(struct zone *zone, struct page *page, int count, > - bool skip_hwpoisoned_pages); > + int migratetype, bool skip_hwpoisoned_pages); > void set_pageblock_migratetype(struct page *page, int migratetype); > int move_freepages_block(struct zone *zone, struct page *page, > int migratetype, int *num_movable); > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 5b4d85ae445c..259aeb22462f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7344,6 +7344,7 @@ void *__init alloc_large_system_hash(const char *tablename, > * race condition. So you can't expect this function should be exact. > */ > bool has_unmovable_pages(struct zone *zone, struct page *page, int count, > + int migratetype, > bool skip_hwpoisoned_pages) > { > unsigned long pfn, iter, found; > @@ -7356,6 +7357,15 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, > if (zone_idx(zone) == ZONE_MOVABLE) > return false; > > + /* > + * CMA allocations (alloc_contig_range) really need to mark isolate > + * CMA pageblocks even when they are not movable in fact so consider > + * them movable here. > + */ > + if (is_migrate_cma(migratetype) && > + is_migrate_cma(get_pageblock_migratetype(page))) > + return false; > + > pfn = page_to_pfn(page); > for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) { > unsigned long check = pfn + iter; > @@ -7441,7 +7451,7 @@ bool is_pageblock_removable_nolock(struct page *page) > if (!zone_spans_pfn(zone, pfn)) > return false; > > - return !has_unmovable_pages(zone, page, 0, true); > + return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE, true); > } > > #if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA) > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index 757410d9f758..8616f5332c77 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -14,7 +14,7 @@ > #define CREATE_TRACE_POINTS > #include <trace/events/page_isolation.h> > > -static int set_migratetype_isolate(struct page *page, > +static int set_migratetype_isolate(struct page *page, int migratetype, > bool skip_hwpoisoned_pages) > { > struct zone *zone; > @@ -51,7 +51,7 @@ static int set_migratetype_isolate(struct page *page, > * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. > * We just check MOVABLE pages. > */ > - if (!has_unmovable_pages(zone, page, arg.pages_found, > + if (!has_unmovable_pages(zone, page, arg.pages_found, migratetype, > skip_hwpoisoned_pages)) > ret = 0; > > @@ -63,14 +63,14 @@ static int set_migratetype_isolate(struct page *page, > out: > if (!ret) { > unsigned long nr_pages; > - int migratetype = get_pageblock_migratetype(page); > + int mt = get_pageblock_migratetype(page); > > set_pageblock_migratetype(page, MIGRATE_ISOLATE); > zone->nr_isolate_pageblock++; > nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE, > NULL); > > - __mod_zone_freepage_state(zone, -nr_pages, migratetype); > + __mod_zone_freepage_state(zone, -nr_pages, mt); > } > > spin_unlock_irqrestore(&zone->lock, flags); > @@ -182,7 +182,7 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, > pfn += pageblock_nr_pages) { > page = __first_valid_page(pfn, pageblock_nr_pages); > if (page && > - set_migratetype_isolate(page, skip_hwpoisoned_pages)) { > + set_migratetype_isolate(page, migratetype, skip_hwpoisoned_pages)) { > undo_pfn = pfn; > goto undo; > } > -- > 2.14.2 > > -- > Michal Hocko > SUSE Labs -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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