From: Zi Yan ziy@nvidia.com
mainline inclusion from mainline-v6.9-rc1 commit 733aea0b3a7bba0451dfc19322665de13a5b7af4 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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Before last commit, memory compaction only migrates order-0 folios and skips >0 order folios. Last commit splits all >0 order folios during compaction. This commit migrates >0 order folios during compaction by keeping isolated free pages at their original size without splitting them into order-0 pages and using them directly during migration process.
What is different from the prior implementation: 1. All isolated free pages are kept in a NR_PAGE_ORDERS array of page lists, where each page list stores free pages in the same order. 2. All free pages are not post_alloc_hook() processed nor buddy pages, although their orders are stored in first page's private like buddy pages. 3. During migration, in new page allocation time (i.e., in compaction_alloc()), free pages are then processed by post_alloc_hook(). When migration fails and a new page is returned (i.e., in compaction_free()), free pages are restored by reversing the post_alloc_hook() operations using newly added free_pages_prepare_fpi_none().
Step 3 is done for a latter optimization that splitting and/or merging free pages during compaction becomes easier.
Note: without splitting free pages, compaction can end prematurely due to migration will return -ENOMEM even if there is free pages. This happens when no order-0 free page exist and compaction_alloc() return NULL.
Link: https://lkml.kernel.org/r/20240220183220.1451315-4-zi.yan@sent.com Signed-off-by: Zi Yan ziy@nvidia.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: Huang Ying ying.huang@intel.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 Conflicts: mm/internal.h [ Fix context conflict with dpool_* functions ]. Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/compaction.c | 140 +++++++++++++++++++++++++++--------------------- mm/internal.h | 4 +- mm/page_alloc.c | 2 +- 3 files changed, 83 insertions(+), 63 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c index a135a50e7591..44c1b5f32e3d 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -83,45 +83,56 @@ static inline bool is_via_compact_memory(int order) { return false; } #define COMPACTION_HPAGE_ORDER (PMD_SHIFT - PAGE_SHIFT) #endif
-static unsigned long release_freepages(struct list_head *freelist) +static void split_map_pages(struct list_head *freepages) { + unsigned int i, order; struct page *page, *next; - unsigned long high_pfn = 0; + LIST_HEAD(tmp_list);
- list_for_each_entry_safe(page, next, freelist, lru) { - unsigned long pfn = page_to_pfn(page); - list_del(&page->lru); - __free_page(page); - if (pfn > high_pfn) - high_pfn = pfn; - } + for (order = 0; order < NR_PAGE_ORDERS; order++) { + list_for_each_entry_safe(page, next, &freepages[order], lru) { + unsigned int nr_pages;
- return high_pfn; + list_del(&page->lru); + + nr_pages = 1 << order; + + post_alloc_hook(page, order, __GFP_MOVABLE); + if (order) + split_page(page, order); + + for (i = 0; i < nr_pages; i++) { + list_add(&page->lru, &tmp_list); + page++; + } + } + list_splice_init(&tmp_list, &freepages[0]); + } }
-static void split_map_pages(struct list_head *list) +static unsigned long release_free_list(struct list_head *freepages) { - unsigned int i, order, nr_pages; - struct page *page, *next; - LIST_HEAD(tmp_list); - - list_for_each_entry_safe(page, next, list, lru) { - list_del(&page->lru); + int order; + unsigned long high_pfn = 0;
- order = page_private(page); - nr_pages = 1 << order; + for (order = 0; order < NR_PAGE_ORDERS; order++) { + struct page *page, *next;
- post_alloc_hook(page, order, __GFP_MOVABLE); - if (order) - split_page(page, order); + list_for_each_entry_safe(page, next, &freepages[order], lru) { + unsigned long pfn = page_to_pfn(page);
- for (i = 0; i < nr_pages; i++) { - list_add(&page->lru, &tmp_list); - page++; + list_del(&page->lru); + /* + * Convert free pages into post allocation pages, so + * that we can free them via __free_page. + */ + post_alloc_hook(page, order, __GFP_MOVABLE); + __free_pages(page, order); + if (pfn > high_pfn) + high_pfn = pfn; } } - - list_splice(&tmp_list, list); + return high_pfn; }
#ifdef CONFIG_COMPACTION @@ -674,7 +685,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, nr_scanned += isolated - 1; total_isolated += isolated; cc->nr_freepages += isolated; - list_add_tail(&page->lru, freelist); + list_add_tail(&page->lru, &freelist[order]);
if (!strict && cc->nr_migratepages <= cc->nr_freepages) { blockpfn += isolated; @@ -739,7 +750,11 @@ isolate_freepages_range(struct compact_control *cc, unsigned long start_pfn, unsigned long end_pfn) { unsigned long isolated, pfn, block_start_pfn, block_end_pfn; - LIST_HEAD(freelist); + int order; + struct list_head tmp_freepages[NR_PAGE_ORDERS]; + + for (order = 0; order < NR_PAGE_ORDERS; order++) + INIT_LIST_HEAD(&tmp_freepages[order]);
pfn = start_pfn; block_start_pfn = pageblock_start_pfn(pfn); @@ -770,7 +785,7 @@ isolate_freepages_range(struct compact_control *cc, break;
isolated = isolate_freepages_block(cc, &isolate_start_pfn, - block_end_pfn, &freelist, 0, true); + block_end_pfn, tmp_freepages, 0, true);
/* * In strict mode, isolate_freepages_block() returns 0 if @@ -787,15 +802,15 @@ isolate_freepages_range(struct compact_control *cc, */ }
- /* __isolate_free_page() does not map the pages */ - split_map_pages(&freelist); - if (pfn < end_pfn) { /* Loop terminated early, cleanup. */ - release_freepages(&freelist); + release_free_list(tmp_freepages); return 0; }
+ /* __isolate_free_page() does not map the pages */ + split_map_pages(tmp_freepages); + /* We don't use freelists for anything. */ return pfn; } @@ -1503,7 +1518,7 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn) if (!page) return;
- isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false); + isolate_freepages_block(cc, &start_pfn, end_pfn, cc->freepages, 1, false);
/* Skip this pageblock in the future as it's full or nearly full */ if (start_pfn == end_pfn && !cc->no_set_skip_hint) @@ -1632,7 +1647,7 @@ static void fast_isolate_freepages(struct compact_control *cc) nr_scanned += nr_isolated - 1; total_isolated += nr_isolated; cc->nr_freepages += nr_isolated; - list_add_tail(&page->lru, &cc->freepages); + list_add_tail(&page->lru, &cc->freepages[order]); count_compact_events(COMPACTISOLATED, nr_isolated); } else { /* If isolation fails, abort the search */ @@ -1709,13 +1724,12 @@ static void isolate_freepages(struct compact_control *cc) unsigned long isolate_start_pfn; /* exact pfn we start at */ unsigned long block_end_pfn; /* end of current pageblock */ unsigned long low_pfn; /* lowest pfn scanner is able to scan */ - struct list_head *freelist = &cc->freepages; unsigned int stride;
/* Try a small search of the free lists for a candidate */ fast_isolate_freepages(cc); if (cc->nr_freepages) - goto splitmap; + return;
/* * Initialise the free scanner. The starting point is where we last @@ -1775,7 +1789,7 @@ static void isolate_freepages(struct compact_control *cc)
/* Found a block suitable for isolating free pages from. */ nr_isolated = isolate_freepages_block(cc, &isolate_start_pfn, - block_end_pfn, freelist, stride, false); + block_end_pfn, cc->freepages, stride, false);
/* Update the skip hint if the full pageblock was scanned */ if (isolate_start_pfn == block_end_pfn) @@ -1816,10 +1830,6 @@ static void isolate_freepages(struct compact_control *cc) * and the loop terminated due to isolate_start_pfn < low_pfn */ cc->free_pfn = isolate_start_pfn; - -splitmap: - /* __isolate_free_page() does not map the pages */ - split_map_pages(freelist); }
/* @@ -1830,24 +1840,22 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) { struct compact_control *cc = (struct compact_control *)data; struct folio *dst; + int order = folio_order(src);
- /* this makes migrate_pages() split the source page and retry */ - if (folio_test_large(src)) - return NULL; - - if (list_empty(&cc->freepages)) { + if (list_empty(&cc->freepages[order])) { isolate_freepages(cc); - - if (list_empty(&cc->freepages)) + if (list_empty(&cc->freepages[order])) return NULL; }
- dst = list_entry(cc->freepages.next, struct folio, lru); + dst = list_first_entry(&cc->freepages[order], struct folio, lru); list_del(&dst->lru); - cc->nr_freepages--; - cc->nr_migratepages--; - - return dst; + post_alloc_hook(&dst->page, order, __GFP_MOVABLE); + if (order) + prep_compound_page(&dst->page, order); + cc->nr_freepages -= 1 << order; + cc->nr_migratepages -= 1 << order; + return page_rmappable_folio(&dst->page); }
/* @@ -1858,10 +1866,19 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) static void compaction_free(struct folio *dst, unsigned long data) { struct compact_control *cc = (struct compact_control *)data; + int order = folio_order(dst); + struct page *page = &dst->page;
- list_add(&dst->lru, &cc->freepages); - cc->nr_freepages++; - cc->nr_migratepages++; + if (folio_put_testzero(dst)) { + free_pages_prepare(page, order); + list_add(&dst->lru, &cc->freepages[order]); + cc->nr_freepages += 1 << order; + } + cc->nr_migratepages += 1 << order; + /* + * someone else has referenced the page, we cannot take it back to our + * free list. + */ }
/* possible outcome of isolate_migratepages */ @@ -2477,6 +2494,7 @@ compact_zone(struct compact_control *cc, struct capture_control *capc) const bool sync = cc->mode != MIGRATE_ASYNC; bool update_cached; unsigned int nr_succeeded = 0, nr_migratepages; + int order;
/* * These counters track activities during zone compaction. Initialize @@ -2486,7 +2504,8 @@ compact_zone(struct compact_control *cc, struct capture_control *capc) cc->total_free_scanned = 0; cc->nr_migratepages = 0; cc->nr_freepages = 0; - INIT_LIST_HEAD(&cc->freepages); + for (order = 0; order < NR_PAGE_ORDERS; order++) + INIT_LIST_HEAD(&cc->freepages[order]); INIT_LIST_HEAD(&cc->migratepages);
cc->migratetype = gfp_migratetype(cc->gfp_mask); @@ -2678,7 +2697,7 @@ compact_zone(struct compact_control *cc, struct capture_control *capc) * so we don't leave any returned pages behind in the next attempt. */ if (cc->nr_freepages > 0) { - unsigned long free_pfn = release_freepages(&cc->freepages); + unsigned long free_pfn = release_free_list(cc->freepages);
cc->nr_freepages = 0; VM_BUG_ON(free_pfn == 0); @@ -2697,7 +2716,6 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
trace_mm_compaction_end(cc, start_pfn, end_pfn, sync, ret);
- VM_BUG_ON(!list_empty(&cc->freepages)); VM_BUG_ON(!list_empty(&cc->migratepages));
return ret; diff --git a/mm/internal.h b/mm/internal.h index 3730156306da..176d94508d29 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -540,6 +540,8 @@ extern void prep_compound_page(struct page *page, unsigned int order);
extern void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags); +extern bool free_pages_prepare(struct page *page, unsigned int order); + #ifdef CONFIG_DYNAMIC_POOL extern bool dpool_free_page_prepare(struct page *page); extern int dpool_check_new_page(struct page *page); @@ -580,7 +582,7 @@ int split_free_page(struct page *free_page, * completes when free_pfn <= migrate_pfn */ struct compact_control { - struct list_head freepages; /* List of free pages to migrate to */ + struct list_head freepages[NR_PAGE_ORDERS]; /* List of free pages to migrate to */ struct list_head migratepages; /* List of pages being migrated */ unsigned int nr_freepages; /* Number of isolated free pages */ unsigned int nr_migratepages; /* Number of pages to migrate */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 048d0bd2c8f3..fafdbf5ae169 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1080,7 +1080,7 @@ static void kernel_init_pages(struct page *page, int numpages) kasan_enable_current(); }
-static __always_inline bool free_pages_prepare(struct page *page, +__always_inline bool free_pages_prepare(struct page *page, unsigned int order) { int bad = 0;