From: Zi Yan ziy@nvidia.com
mainline inclusion from mainline-v6.9-rc1 commit ee6f62fd34f0bb99ef93f799bcf5fc6a6b24945b category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9CXS6 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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migrate_pages() supports >0 order folio migration and during compaction, even if compaction_alloc() cannot provide >0 order free pages, migrate_pages() can split the source page and try to migrate the base pages from the split. It can be a baseline and start point for adding support for compacting >0 order folios.
Link: https://lkml.kernel.org/r/20240220183220.1451315-3-zi.yan@sent.com Signed-off-by: Zi Yan ziy@nvidia.com Suggested-by: Huang Ying ying.huang@intel.com Reviewed-by: Baolin Wang baolin.wang@linux.alibaba.com Reviewed-by: Vlastimil Babka vbabka@suse.cz Tested-by: Baolin Wang baolin.wang@linux.alibaba.com Tested-by: Yu Zhao yuzhao@google.com Cc: Adam Manzanares a.manzanares@samsung.com Cc: David Hildenbrand david@redhat.com Cc: Johannes Weiner hannes@cmpxchg.org Cc: Kemeng Shi shikemeng@huaweicloud.com Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Luis Chamberlain mcgrof@kernel.org Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Mel Gorman mgorman@techsingularity.net Cc: Ryan Roberts ryan.roberts@arm.com Cc: Vishal Moola (Oracle) vishal.moola@gmail.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Yin Fengwei fengwei.yin@intel.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/compaction.c | 101 ++++++++++++++++++++++++++++++++++++------------ 1 file changed, 76 insertions(+), 25 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c index 719481430d24..a135a50e7591 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -44,9 +44,22 @@ static inline void count_compact_events(enum vm_event_item item, long delta) { count_vm_events(item, delta); } + +/* + * order == -1 is expected when compacting proactively via + * 1. /proc/sys/vm/compact_memory + * 2. /sys/devices/system/node/nodex/compact + * 3. /proc/sys/vm/compaction_proactiveness + */ +static inline bool is_via_compact_memory(int order) +{ + return order == -1; +} + #else #define count_compact_event(item) do { } while (0) #define count_compact_events(item, delta) do { } while (0) +static inline bool is_via_compact_memory(int order) { return false; } #endif
#if defined CONFIG_COMPACTION || defined CONFIG_CMA @@ -820,6 +833,32 @@ static bool too_many_isolated(struct compact_control *cc) return too_many; }
+/** + * skip_isolation_on_order() - determine when to skip folio isolation based on + * folio order and compaction target order + * @order: to-be-isolated folio order + * @target_order: compaction target order + * + * This avoids unnecessary folio isolations during compaction. + */ +static bool skip_isolation_on_order(int order, int target_order) +{ + /* + * Unless we are performing global compaction (i.e., + * is_via_compact_memory), skip any folios that are larger than the + * target order: we wouldn't be here if we'd have a free folio with + * the desired target_order, so migrating this folio would likely fail + * later. + */ + if (!is_via_compact_memory(target_order) && order >= target_order) + return true; + /* + * We limit memory compaction to pageblocks and won't try + * creating free blocks of memory that are larger than that. + */ + return order >= pageblock_order; +} + /** * isolate_migratepages_block() - isolate all migrate-able pages within * a single pageblock @@ -950,7 +989,22 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, valid_page = page; }
- if (PageHuge(page) && cc->alloc_contig) { + if (PageHuge(page)) { + /* + * skip hugetlbfs if we are not compacting for pages + * bigger than its order. THPs and other compound pages + * are handled below. + */ + if (!cc->alloc_contig) { + const unsigned int order = compound_order(page); + + if (order <= MAX_PAGE_ORDER) { + low_pfn += (1UL << order) - 1; + nr_scanned += (1UL << order) - 1; + } + goto isolate_fail; + } + /* for alloc_contig case */ if (locked) { unlock_page_lruvec_irqrestore(locked, flags); locked = NULL; @@ -1011,21 +1065,24 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, }
/* - * Regardless of being on LRU, compound pages such as THP and - * hugetlbfs are not to be compacted unless we are attempting - * an allocation much larger than the huge page size (eg CMA). - * We can potentially save a lot of iterations if we skip them - * at once. The check is racy, but we can consider only valid - * values and the only danger is skipping too much. + * Regardless of being on LRU, compound pages such as THP + * (hugetlbfs is handled above) are not to be compacted unless + * we are attempting an allocation larger than the compound + * page size. We can potentially save a lot of iterations if we + * skip them at once. The check is racy, but we can consider + * only valid values and the only danger is skipping too much. */ if (PageCompound(page) && !cc->alloc_contig) { const unsigned int order = compound_order(page);
- if (likely(order <= MAX_PAGE_ORDER)) { - low_pfn += (1UL << order) - 1; - nr_scanned += (1UL << order) - 1; + /* Skip based on page order and compaction target order. */ + if (skip_isolation_on_order(order, cc->order)) { + if (order <= MAX_PAGE_ORDER) { + low_pfn += (1UL << order) - 1; + nr_scanned += (1UL << order) - 1; + } + goto isolate_fail; } - goto isolate_fail; }
/* @@ -1150,10 +1207,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, }
/* - * folio become large since the non-locked check, - * and it's on LRU. + * Check LRU folio order under the lock */ - if (unlikely(folio_test_large(folio) && !cc->alloc_contig)) { + if (unlikely(skip_isolation_on_order(folio_order(folio), + cc->order) && + !cc->alloc_contig)) { low_pfn += folio_nr_pages(folio) - 1; nr_scanned += folio_nr_pages(folio) - 1; folio_set_lru(folio); @@ -1773,6 +1831,10 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) struct compact_control *cc = (struct compact_control *)data; struct folio *dst;
+ /* this makes migrate_pages() split the source page and retry */ + if (folio_test_large(src)) + return NULL; + if (list_empty(&cc->freepages)) { isolate_freepages(cc);
@@ -2078,17 +2140,6 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc) return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE; }
-/* - * order == -1 is expected when compacting proactively via - * 1. /proc/sys/vm/compact_memory - * 2. /sys/devices/system/node/nodex/compact - * 3. /proc/sys/vm/compaction_proactiveness - */ -static inline bool is_via_compact_memory(int order) -{ - return order == -1; -} - /* * Determine whether kswapd is (or recently was!) running on this node. *