From: Kemeng Shi shikemeng@huaweicloud.com

mainline inclusion from mainline-v6.7-rc1 commit 0dfca313a009c83e2ad44b3719dc1222df6c6db5 category: cleanup bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

The next_page is only used to forward page in case target is in second half range. Move forward page directly to remove unnecessary next_page.

Link: https://lkml.kernel.org/r/20230927103514.98281-3-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi shikemeng@huaweicloud.com Acked-by: Naoya Horiguchi naoya.horiguchi@nec.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Oscar Salvador osalvador@suse.de Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_alloc.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c index fb6008b30b48..3cc5d5c7826e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6937,20 +6937,18 @@ static void break_down_buddy_pages(struct zone *zone, struct page *page, int migratetype) { unsigned long size = 1 << high; - struct page *current_buddy, *next_page; + struct page *current_buddy;

while (high > low) { high--; size >>= 1;

if (target >= &page[size]) { - next_page = page + size; current_buddy = page; + page = page + size; } else { - next_page = page; current_buddy = page + size; } - page = next_page;

if (set_page_guard(zone, current_buddy, high, migratetype)) continue;

From: Johannes Weiner hannes@cmpxchg.org

mainline inclusion from mainline-v6.10-rc1 commit 17edeb5d3f761c20fd28f6002f5a9faa53c0a0d8 category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

Patch series "mm: page_alloc: freelist migratetype hygiene", v4.

The page allocator's mobility grouping is intended to keep unmovable pages separate from reclaimable/compactable ones to allow on-demand defragmentation for higher-order allocations and huge pages.

Currently, there are several places where accidental type mixing occurs: an allocation asks for a page of a certain migratetype and receives another. This ruins pageblocks for compaction, which in turn makes allocating huge pages more expensive and less reliable.

The series addresses those causes. The last patch adds type checks on all freelist movements to prevent new violations being introduced.

The benefits can be seen in a mixed workload that stresses the machine with a memcache-type workload and a kernel build job while periodically attempting to allocate batches of THP. The following data is aggregated over 50 consecutive defconfig builds:

VANILLA PATCHED Hugealloc Time mean 165843.93 ( +0.00%) 113025.88 ( -31.85%) Hugealloc Time stddev 158957.35 ( +0.00%) 114716.07 ( -27.83%) Kbuild Real time 310.24 ( +0.00%) 300.73 ( -3.06%) Kbuild User time 1271.13 ( +0.00%) 1259.42 ( -0.92%) Kbuild System time 582.02 ( +0.00%) 559.79 ( -3.81%) THP fault alloc 30585.14 ( +0.00%) 40853.62 ( +33.57%) THP fault fallback 36626.46 ( +0.00%) 26357.62 ( -28.04%) THP fault fail rate % 54.49 ( +0.00%) 39.22 ( -27.53%) Pagealloc fallback 1328.00 ( +0.00%) 1.00 ( -99.85%) Pagealloc type mismatch 181009.50 ( +0.00%) 0.00 ( -100.00%) Direct compact stall 434.56 ( +0.00%) 257.66 ( -40.61%) Direct compact fail 421.70 ( +0.00%) 249.94 ( -40.63%) Direct compact success 12.86 ( +0.00%) 7.72 ( -37.09%) Direct compact success rate % 2.86 ( +0.00%) 2.82 ( -0.96%) Compact daemon scanned migrate 3370059.62 ( +0.00%) 3612054.76 ( +7.18%) Compact daemon scanned free 7718439.20 ( +0.00%) 5386385.02 ( -30.21%) Compact direct scanned migrate 309248.62 ( +0.00%) 176721.04 ( -42.85%) Compact direct scanned free 433582.84 ( +0.00%) 315727.66 ( -27.18%) Compact migrate scanned daemon % 91.20 ( +0.00%) 94.48 ( +3.56%) Compact free scanned daemon % 94.58 ( +0.00%) 94.42 ( -0.16%) Compact total migrate scanned 3679308.24 ( +0.00%) 3788775.80 ( +2.98%) Compact total free scanned 8152022.04 ( +0.00%) 5702112.68 ( -30.05%) Alloc stall 872.04 ( +0.00%) 5156.12 ( +490.71%) Pages kswapd scanned 510645.86 ( +0.00%) 3394.94 ( -99.33%) Pages kswapd reclaimed 134811.62 ( +0.00%) 2701.26 ( -98.00%) Pages direct scanned 99546.06 ( +0.00%) 376407.52 ( +278.12%) Pages direct reclaimed 62123.40 ( +0.00%) 289535.70 ( +366.06%) Pages total scanned 610191.92 ( +0.00%) 379802.46 ( -37.76%) Pages scanned kswapd % 76.36 ( +0.00%) 0.10 ( -98.58%) Swap out 12057.54 ( +0.00%) 15022.98 ( +24.59%) Swap in 209.16 ( +0.00%) 256.48 ( +22.52%) File refaults 17701.64 ( +0.00%) 11765.40 ( -33.53%)

Huge page success rate is higher, allocation latencies are shorter and more predictable.

Stealing (fallback) rate is drastically reduced. Notably, while the vanilla kernel keeps doing fallbacks on an ongoing basis, the patched kernel enters a steady state once the distribution of block types is adequate for the workload. Steals over 50 runs:

VANILLA PATCHED 1504.0 227.0 1557.0 6.0 1391.0 13.0 1080.0 26.0 1057.0 40.0 1156.0 6.0 805.0 46.0 736.0 20.0 1747.0 2.0 1699.0 34.0 1269.0 13.0 1858.0 12.0 907.0 4.0 727.0 2.0 563.0 2.0 3094.0 2.0 10211.0 3.0 2621.0 1.0 5508.0 2.0 1060.0 2.0 538.0 3.0 5773.0 2.0 2199.0 0.0 3781.0 2.0 1387.0 1.0 4977.0 0.0 2865.0 1.0 1814.0 1.0 3739.0 1.0 6857.0 0.0 382.0 0.0 407.0 1.0 3784.0 0.0 297.0 0.0 298.0 0.0 6636.0 0.0 4188.0 0.0 242.0 0.0 9960.0 0.0 5816.0 0.0 354.0 0.0 287.0 0.0 261.0 0.0 140.0 1.0 2065.0 0.0 312.0 0.0 331.0 0.0 164.0 0.0 465.0 1.0 219.0 0.0

Type mismatches are down too. Those count every time an allocation request asks for one migratetype and gets another. This can still occur minimally in the patched kernel due to non-stealing fallbacks, but it's quite rare and follows the pattern of overall fallbacks - once the block type distribution settles, mismatches cease as well:

VANILLA: PATCHED: 182602.0 268.0 135794.0 20.0 88619.0 19.0 95973.0 0.0 129590.0 0.0 129298.0 0.0 147134.0 0.0 230854.0 0.0 239709.0 0.0 137670.0 0.0 132430.0 0.0 65712.0 0.0 57901.0 0.0 67506.0 0.0 63565.0 4.0 34806.0 0.0 42962.0 0.0 32406.0 0.0 38668.0 0.0 61356.0 0.0 57800.0 0.0 41435.0 0.0 83456.0 0.0 65048.0 0.0 28955.0 0.0 47597.0 0.0 75117.0 0.0 55564.0 0.0 38280.0 0.0 52404.0 0.0 26264.0 0.0 37538.0 0.0 19671.0 0.0 30936.0 0.0 26933.0 0.0 16962.0 0.0 44554.0 0.0 46352.0 0.0 24995.0 0.0 35152.0 0.0 12823.0 0.0 21583.0 0.0 18129.0 0.0 31693.0 0.0 28745.0 0.0 33308.0 0.0 31114.0 0.0 35034.0 0.0 12111.0 0.0 24885.0 0.0

Compaction work is markedly reduced despite much better THP rates.

In the vanilla kernel, reclaim seems to have been driven primarily by watermark boosting that happens as a result of fallbacks. With those all but eliminated, watermarks average lower and kswapd does less work. The uptick in direct reclaim is because THP requests have to fend for themselves more often - which is intended policy right now. Aggregate reclaim activity is lowered significantly, though.

This patch (of 10):

The idea behind the cache is to save get_pageblock_migratetype() lookups during bulk freeing. A microbenchmark suggests this isn't helping, though. The pcp migratetype can get stale, which means that bulk freeing has an extra branch to check if the pageblock was isolated while on the pcp.

While the variance overlaps, the cache write and the branch seem to make this a net negative. The following test allocates and frees batches of 10,000 pages (~3x the pcp high marks to trigger flushing):

Before: 8,668.48 msec task-clock # 99.735 CPUs utilized ( +- 2.90% ) 19 context-switches # 4.341 /sec ( +- 3.24% ) 0 cpu-migrations # 0.000 /sec 17,440 page-faults # 3.984 K/sec ( +- 2.90% ) 41,758,692,473 cycles # 9.541 GHz ( +- 2.90% ) 126,201,294,231 instructions # 5.98 insn per cycle ( +- 2.90% ) 25,348,098,335 branches # 5.791 G/sec ( +- 2.90% ) 33,436,921 branch-misses # 0.26% of all branches ( +- 2.90% )

0.0869148 +- 0.0000302 seconds time elapsed ( +- 0.03% )

After: 8,444.81 msec task-clock # 99.726 CPUs utilized ( +- 2.90% ) 22 context-switches # 5.160 /sec ( +- 3.23% ) 0 cpu-migrations # 0.000 /sec 17,443 page-faults # 4.091 K/sec ( +- 2.90% ) 40,616,738,355 cycles # 9.527 GHz ( +- 2.90% ) 126,383,351,792 instructions # 6.16 insn per cycle ( +- 2.90% ) 25,224,985,153 branches # 5.917 G/sec ( +- 2.90% ) 32,236,793 branch-misses # 0.25% of all branches ( +- 2.90% )

0.0846799 +- 0.0000412 seconds time elapsed ( +- 0.05% )

A side effect is that this also ensures that pages whose pageblock gets stolen while on the pcplist end up on the right freelist and we don't perform potentially type-incompatible buddy merges (or skip merges when we shouldn't), which is likely beneficial to long-term fragmentation management, although the effects would be harder to measure. Settle for simpler and faster code as justification here.

Link: https://lkml.kernel.org/r/20240320180429.678181-1-hannes@cmpxchg.org Link: https://lkml.kernel.org/r/20240320180429.678181-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner hannes@cmpxchg.org Acked-by: Zi Yan ziy@nvidia.com Reviewed-by: Vlastimil Babka vbabka@suse.cz Acked-by: Mel Gorman mgorman@techsingularity.net Tested-by: "Huang, Ying" ying.huang@intel.com Tested-by: Baolin Wang baolin.wang@linux.alibaba.com Cc: David Hildenbrand david@redhat.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Conflicts: mm/page_alloc.c [ Context conflicts with commit 62b208c4859c and ae577de78c12. ] Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_alloc.c | 66 +++++++++++-------------------------------------- 1 file changed, 14 insertions(+), 52 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ff0940ab0fe6..3d4932cd2332 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -207,24 +207,6 @@ EXPORT_SYMBOL(node_states);

gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;

-/* - * A cached value of the page's pageblock's migratetype, used when the page is - * put on a pcplist. Used to avoid the pageblock migratetype lookup when - * freeing from pcplists in most cases, at the cost of possibly becoming stale. - * Also the migratetype set in the page does not necessarily match the pcplist - * index, e.g. page might have MIGRATE_CMA set but be on a pcplist with any - * other index - this ensures that it will be put on the correct CMA freelist. - */ -static inline int get_pcppage_migratetype(struct page *page) -{ - return page->index; -} - -static inline void set_pcppage_migratetype(struct page *page, int migratetype) -{ - page->index = migratetype; -} - #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE unsigned int pageblock_order __read_mostly; #endif @@ -1186,7 +1168,6 @@ static void free_pcppages_bulk(struct zone *zone, int count, { unsigned long flags; unsigned int order; - bool isolated_pageblocks; struct page *page;

/* @@ -1199,7 +1180,6 @@ static void free_pcppages_bulk(struct zone *zone, int count, pindex = pindex - 1;

spin_lock_irqsave(&zone->lock, flags); - isolated_pageblocks = has_isolate_pageblock(zone);

while (count > 0) { struct list_head *list; @@ -1215,23 +1195,19 @@ static void free_pcppages_bulk(struct zone *zone, int count, order = pindex_to_order(pindex); nr_pages = 1 << order; do { + unsigned long pfn; int mt;

page = list_last_entry(list, struct page, pcp_list); - mt = get_pcppage_migratetype(page); + pfn = page_to_pfn(page); + mt = get_pfnblock_migratetype(page, pfn);

/* must delete to avoid corrupting pcp list */ list_del(&page->pcp_list); count -= nr_pages; pcp->count -= nr_pages;

- /* MIGRATE_ISOLATE page should not go to pcplists */ - VM_BUG_ON_PAGE(is_migrate_isolate(mt), page); - /* Pageblock could have been isolated meanwhile */ - if (unlikely(isolated_pageblocks)) - mt = get_pageblock_migratetype(page); - - __free_one_page(page, page_to_pfn(page), zone, order, mt, FPI_NONE); + __free_one_page(page, pfn, zone, order, mt, FPI_NONE); trace_mm_page_pcpu_drain(page, order, mt); } while (count > 0 && !list_empty(list)); } @@ -1591,7 +1567,6 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order, continue; del_page_from_free_list(page, zone, current_order); expand(zone, page, order, current_order, migratetype); - set_pcppage_migratetype(page, migratetype); trace_mm_page_alloc_zone_locked(page, order, migratetype, pcp_allowed_order(order) && migratetype < MIGRATE_PCPTYPES); @@ -2162,7 +2137,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, * pages are ordered properly. */ list_add_tail(&page->pcp_list, list); - if (is_migrate_cma(get_pcppage_migratetype(page))) + if (is_migrate_cma(get_pageblock_migratetype(page))) __mod_zone_page_state(zone, NR_FREE_CMA_PAGES, -(1 << order)); } @@ -2362,19 +2337,6 @@ void drain_all_pages(struct zone *zone) __drain_all_pages(zone, false); }

-static bool free_unref_page_prepare(struct page *page, unsigned long pfn, - unsigned int order) -{ - int migratetype; - - if (!free_pages_prepare(page, order)) - return false; - - migratetype = get_pfnblock_migratetype(page, pfn); - set_pcppage_migratetype(page, migratetype); - return true; -} - static int nr_pcp_free(struct per_cpu_pages *pcp, int batch, int high, bool free_high) { int min_nr_free, max_nr_free; @@ -2517,7 +2479,7 @@ void free_unref_page(struct page *page, unsigned int order) return; }

- if (!free_unref_page_prepare(page, pfn, order)) + if (!free_pages_prepare(page, order)) return;

/* @@ -2527,7 +2489,7 @@ void free_unref_page(struct page *page, unsigned int order) * get those areas back if necessary. Otherwise, we may have to free * excessively into the page allocator */ - migratetype = pcpmigratetype = get_pcppage_migratetype(page); + migratetype = pcpmigratetype = get_pfnblock_migratetype(page, pfn); if (unlikely(migratetype >= MIGRATE_PCPTYPES)) { if (unlikely(is_migrate_isolate(migratetype))) { free_one_page(page_zone(page), page, pfn, order, migratetype, FPI_NONE); @@ -2570,14 +2532,14 @@ void free_unref_folios(struct folio_batch *folios) }

folio_undo_large_rmappable(folio); - if (!free_unref_page_prepare(&folio->page, pfn, order)) + if (!free_pages_prepare(&folio->page, order)) continue;

/* * Free isolated folios and orders not handled on the PCP * directly to the allocator, see comment in free_unref_page. */ - migratetype = get_pcppage_migratetype(&folio->page); + migratetype = get_pfnblock_migratetype(&folio->page, pfn); if (!pcp_allowed_order(order) || is_migrate_isolate(migratetype)) { free_one_page(folio_zone(folio), &folio->page, pfn, @@ -2594,10 +2556,11 @@ void free_unref_folios(struct folio_batch *folios) for (i = 0; i < folios->nr; i++) { struct folio *folio = folios->folios[i]; struct zone *zone = folio_zone(folio); + unsigned long pfn = folio_pfn(folio); unsigned int order = (unsigned long)folio->private;

folio->private = NULL; - migratetype = get_pcppage_migratetype(&folio->page); + migratetype = get_pfnblock_migratetype(&folio->page, pfn);

/* Different zone requires a different pcp lock */ if (zone != locked_zone) { @@ -2614,9 +2577,8 @@ void free_unref_folios(struct folio_batch *folios) pcp = pcp_spin_trylock(zone->per_cpu_pageset); if (unlikely(!pcp)) { pcp_trylock_finish(UP_flags); - free_one_page(zone, &folio->page, - folio_pfn(folio), order, - migratetype, FPI_NONE); + free_one_page(zone, &folio->page, pfn, + order, migratetype, FPI_NONE); locked_zone = NULL; continue; } @@ -2785,7 +2747,7 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone, } } __mod_zone_freepage_state(zone, -(1 << order), - get_pcppage_migratetype(page)); + get_pageblock_migratetype(page)); spin_unlock_irqrestore(&zone->lock, flags); } while (check_new_pages(page, order));

From: Johannes Weiner hannes@cmpxchg.org

mainline inclusion from mainline-v6.10-rc1 commit e6cf9e1c4cde8a53385423ecb8ca581097f42e02 category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

The buddy allocator coalesces compatible blocks during freeing, but it doesn't update the types of the subblocks to match. When an allocation later breaks the chunk down again, its pieces will be put on freelists of the wrong type. This encourages incompatible page mixing (ask for one type, get another), and thus long-term fragmentation.

Update the subblocks when merging a larger chunk, such that a later expand() will maintain freelist type hygiene.

Link: https://lkml.kernel.org/r/20240320180429.678181-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner hannes@cmpxchg.org Reviewed-by: Zi Yan ziy@nvidia.com Reviewed-by: Vlastimil Babka vbabka@suse.cz Acked-by: Mel Gorman mgorman@techsingularity.net Tested-by: "Huang, Ying" ying.huang@intel.com Tested-by: Baolin Wang baolin.wang@linux.alibaba.com Cc: David Hildenbrand david@redhat.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_alloc.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c index dad180df69da..3d7e0f110868 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -779,10 +779,17 @@ static inline void __free_one_page(struct page *page, */ int buddy_mt = get_pfnblock_migratetype(buddy, buddy_pfn);

- if (migratetype != buddy_mt - && (!migratetype_is_mergeable(migratetype) || - !migratetype_is_mergeable(buddy_mt))) - goto done_merging; + if (migratetype != buddy_mt) { + if (!migratetype_is_mergeable(migratetype) || + !migratetype_is_mergeable(buddy_mt)) + goto done_merging; + /* + * Match buddy type. This ensures that + * an expand() down the line puts the + * sub-blocks on the right freelists. + */ + set_pageblock_migratetype(buddy, migratetype); + } }

/*

From: Johannes Weiner hannes@cmpxchg.org

mainline inclusion from mainline-v6.10-rc1 commit 2dd482ba627de15d67f0c0ed445133c8ae9b201b category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

When a block is partially outside the zone of the cursor page, the function cuts the range to the pivot page instead of the zone start. This can leave large parts of the block behind, which encourages incompatible page mixing down the line (ask for one type, get another), and thus long-term fragmentation.

This triggers reliably on the first block in the DMA zone, whose start_pfn is 1. The block is stolen, but everything before the pivot page (which was often hundreds of pages) is left on the old list.

Link: https://lkml.kernel.org/r/20240320180429.678181-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner hannes@cmpxchg.org Reviewed-by: Vlastimil Babka vbabka@suse.cz Tested-by: Baolin Wang baolin.wang@linux.alibaba.com Cc: David Hildenbrand david@redhat.com Cc: "Huang, Ying" ying.huang@intel.com Cc: Mel Gorman mgorman@techsingularity.net Cc: Zi Yan ziy@nvidia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_alloc.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7e3593318813..a101f5f550dc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1661,9 +1661,15 @@ int move_freepages_block(struct zone *zone, struct page *page, start_pfn = pageblock_start_pfn(pfn); end_pfn = pageblock_end_pfn(pfn) - 1;

- /* Do not cross zone boundaries */ + /* + * The caller only has the lock for @zone, don't touch ranges + * that straddle into other zones. While we could move part of + * the range that's inside the zone, this call is usually + * accompanied by other operations such as migratetype updates + * which also should be locked. + */ if (!zone_spans_pfn(zone, start_pfn)) - start_pfn = pfn; + return 0; if (!zone_spans_pfn(zone, end_pfn)) return 0;

From: Johannes Weiner hannes@cmpxchg.org

mainline inclusion from mainline-v6.10-rc1 commit 55612e80e722ac554cc5e80df05555b4f8d40c37 category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

There are three freeing paths that read the page's migratetype optimistically before grabbing the zone lock. When this races with block stealing, those pages go on the wrong freelist.

The paths in question are: - when freeing >costly orders that aren't THP - when freeing pages to the buddy upon pcp lock contention - when freeing pages that are isolated - when freeing pages initially during boot - when freeing the remainder in alloc_pages_exact() - when "accepting" unaccepted VM host memory before first use - when freeing pages during unpoisoning

None of these are so hot that they would need this optimization at the cost of hampering defrag efforts. Especially when contrasted with the fact that the most common buddy freeing path - free_pcppages_bulk - is checking the migratetype under the zone->lock just fine.

In addition, isolated pages need to look up the migratetype under the lock anyway, which adds branches to the locked section, and results in a double lookup when the pages are in fact isolated.

Move the lookups into the lock.

Link: https://lkml.kernel.org/r/20240320180429.678181-8-hannes@cmpxchg.org Signed-off-by: Johannes Weiner hannes@cmpxchg.org Reported-by: Vlastimil Babka vbabka@suse.cz Reviewed-by: Vlastimil Babka vbabka@suse.cz Tested-by: Baolin Wang baolin.wang@linux.alibaba.com Cc: David Hildenbrand david@redhat.com Cc: "Huang, Ying" ying.huang@intel.com Cc: Mel Gorman mgorman@techsingularity.net Cc: Zi Yan ziy@nvidia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Conflicts: mm/page_alloc.c [ Context conflict with commit 2ae116c3257d. ] Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_alloc.c | 52 ++++++++++++++++++------------------------------- 1 file changed, 19 insertions(+), 33 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ba85db6cf987..cae51fd0b7b2 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1222,18 +1222,15 @@ static void free_pcppages_bulk(struct zone *zone, int count, spin_unlock_irqrestore(&zone->lock, flags); }

-static void free_one_page(struct zone *zone, - struct page *page, unsigned long pfn, - unsigned int order, - int migratetype, fpi_t fpi_flags) +static void free_one_page(struct zone *zone, struct page *page, + unsigned long pfn, unsigned int order, + fpi_t fpi_flags) { unsigned long flags; + int migratetype;

spin_lock_irqsave(&zone->lock, flags); - if (unlikely(has_isolate_pageblock(zone) || - is_migrate_isolate(migratetype))) { - migratetype = get_pfnblock_migratetype(page, pfn); - } + migratetype = get_pfnblock_migratetype(page, pfn); __free_one_page(page, pfn, zone, order, migratetype, fpi_flags); spin_unlock_irqrestore(&zone->lock, flags); } @@ -1241,21 +1238,13 @@ static void free_one_page(struct zone *zone, static void __free_pages_ok(struct page *page, unsigned int order, fpi_t fpi_flags) { - int migratetype; unsigned long pfn = page_to_pfn(page); struct zone *zone = page_zone(page);

if (!free_pages_prepare(page, order)) return;

- /* - * Calling get_pfnblock_migratetype() without spin_lock_irqsave() here - * is used to avoid calling get_pfnblock_migratetype() under the lock. - * This will reduce the lock holding time. - */ - migratetype = get_pfnblock_migratetype(page, pfn); - - free_one_page(zone, page, pfn, order, migratetype, fpi_flags); + free_one_page(zone, page, pfn, order, fpi_flags);

__count_vm_events(PGFREE, 1 << order); } @@ -2518,7 +2507,7 @@ void free_unref_page(struct page *page, unsigned int order) struct per_cpu_pages *pcp; struct zone *zone; unsigned long pfn = page_to_pfn(page); - int migratetype, pcpmigratetype; + int migratetype;

if (page_from_dynamic_pool(page)) { dynamic_pool_free_page(page); @@ -2540,23 +2529,23 @@ void free_unref_page(struct page *page, unsigned int order) * get those areas back if necessary. Otherwise, we may have to free * excessively into the page allocator */ - migratetype = pcpmigratetype = get_pfnblock_migratetype(page, pfn); + migratetype = get_pfnblock_migratetype(page, pfn); if (unlikely(migratetype >= MIGRATE_PCPTYPES)) { if (unlikely(is_migrate_isolate(migratetype))) { - free_one_page(page_zone(page), page, pfn, order, migratetype, FPI_NONE); + free_one_page(page_zone(page), page, pfn, order, FPI_NONE); return; } - pcpmigratetype = MIGRATE_MOVABLE; + migratetype = MIGRATE_MOVABLE; }

zone = page_zone(page); pcp_trylock_prepare(UP_flags); pcp = pcp_spin_trylock(zone->per_cpu_pageset); if (pcp) { - free_unref_page_commit(zone, pcp, page, pcpmigratetype, order); + free_unref_page_commit(zone, pcp, page, migratetype, order); pcp_spin_unlock(pcp); } else { - free_one_page(zone, page, pfn, order, migratetype, FPI_NONE); + free_one_page(zone, page, pfn, order, FPI_NONE); } pcp_trylock_finish(UP_flags); } @@ -2590,12 +2579,8 @@ void free_unref_folios(struct folio_batch *folios) * allocator. */ if (!pcp_allowed_order(order)) { - int migratetype; - - migratetype = get_pfnblock_migratetype(&folio->page, - pfn); - free_one_page(folio_zone(folio), &folio->page, pfn, - order, migratetype, FPI_NONE); + free_one_page(folio_zone(folio), &folio->page, + pfn, order, FPI_NONE); continue; } folio->private = (void *)(unsigned long)order; @@ -2631,7 +2616,7 @@ void free_unref_folios(struct folio_batch *folios) */ if (is_migrate_isolate(migratetype)) { free_one_page(zone, &folio->page, pfn, - order, migratetype, FPI_NONE); + order, FPI_NONE); continue; }

@@ -2644,7 +2629,7 @@ void free_unref_folios(struct folio_batch *folios) if (unlikely(!pcp)) { pcp_trylock_finish(UP_flags); free_one_page(zone, &folio->page, pfn, - order, migratetype, FPI_NONE); + order, FPI_NONE); continue; } locked_zone = zone; @@ -7022,13 +7007,14 @@ bool take_page_off_buddy(struct page *page) bool put_page_back_buddy(struct page *page) { struct zone *zone = page_zone(page); - unsigned long pfn = page_to_pfn(page); unsigned long flags; - int migratetype = get_pfnblock_migratetype(page, pfn); bool ret = false;

spin_lock_irqsave(&zone->lock, flags); if (put_page_testzero(page)) { + unsigned long pfn = page_to_pfn(page); + int migratetype = get_pfnblock_migratetype(page, pfn); + ClearPageHWPoisonTakenOff(page); __free_one_page(page, pfn, zone, 0, migratetype, FPI_NONE); if (TestClearPageHWPoison(page)) {

From: Johannes Weiner hannes@cmpxchg.org

mainline inclusion from mainline-v6.10-rc1 commit fd919a85cd55be5d00a6a7372071f44c8eafb825 category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

Page isolation currently sets MIGRATE_ISOLATE on a block, then drops zone->lock and scans the block for straddling buddies to split up. Because this happens non-atomically wrt the page allocator, it's possible for allocations to get a buddy whose first block is a regular pcp migratetype but whose tail is isolated. This means that in certain cases memory can still be allocated after isolation. It will also trigger the freelist type hygiene warnings in subsequent patches.

start_isolate_page_range() isolate_single_pageblock() set_migratetype_isolate(tail) lock zone->lock move_freepages_block(tail) // nop set_pageblock_migratetype(tail) unlock zone->lock __rmqueue_smallest() del_page_from_freelist(head) expand(head, head_mt) WARN(head_mt != tail_mt) start_pfn = ALIGN_DOWN(MAX_ORDER_NR_PAGES) for (pfn = start_pfn, pfn < end_pfn) if (PageBuddy()) split_free_page(head)

Introduce a variant of move_freepages_block() provided by the allocator specifically for page isolation; it moves free pages, converts the block, and handles the splitting of straddling buddies while holding zone->lock.

The allocator knows that pageblocks and buddies are always naturally aligned, which means that buddies can only straddle blocks if they're actually >pageblock_order. This means the search-and-split part can be simplified compared to what page isolation used to do.

Also tighten up the page isolation code around the expectations of which pages can be large, and how they are freed.

Based on extensive discussions with and invaluable input from Zi Yan.

[hannes@cmpxchg.org: work around older gcc warning] Link: https://lkml.kernel.org/r/20240321142426.GB777580@cmpxchg.org Link: https://lkml.kernel.org/r/20240320180429.678181-10-hannes@cmpxchg.org Signed-off-by: Johannes Weiner hannes@cmpxchg.org Reviewed-by: Vlastimil Babka vbabka@suse.cz Tested-by: Baolin Wang baolin.wang@linux.alibaba.com Cc: David Hildenbrand david@redhat.com Cc: "Huang, Ying" ying.huang@intel.com Cc: Mel Gorman mgorman@techsingularity.net Cc: Zi Yan ziy@nvidia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Conflicts: mm/internal.h mm/page_alloc.c mm/page_isolation.c [ Context conflict due to miss MAX_PAGE_ORDER. ] Signed-off-by: Liu Shixin liushixin2@huawei.com --- include/linux/page-isolation.h | 4 +- mm/internal.h | 4 - mm/page_alloc.c | 204 +++++++++++++++++++-------------- mm/page_isolation.c | 106 ++++++----------- 4 files changed, 155 insertions(+), 163 deletions(-)

diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h index 8550b3c91480..c16db0067090 100644 --- a/include/linux/page-isolation.h +++ b/include/linux/page-isolation.h @@ -34,7 +34,9 @@ static inline bool is_migrate_isolate(int migratetype) #define REPORT_FAILURE 0x2

void set_pageblock_migratetype(struct page *page, int migratetype); -int move_freepages_block(struct zone *zone, struct page *page, int migratetype); + +bool move_freepages_block_isolate(struct zone *zone, struct page *page, + int migratetype);

int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, int migratetype, int flags, gfp_t gfp_flags); diff --git a/mm/internal.h b/mm/internal.h index 0478e5dab55b..de564608dfa6 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -693,10 +693,6 @@ extern void *memmap_alloc(phys_addr_t size, phys_addr_t align, void memmap_init_range(unsigned long, int, unsigned long, unsigned long, unsigned long, enum meminit_context, struct vmem_altmap *, int);

- -int split_free_page(struct page *free_page, - unsigned int order, unsigned long split_pfn_offset); - #if defined CONFIG_COMPACTION || defined CONFIG_CMA

#define MAX_PAGE_ORDER MAX_ORDER diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6f59b8e73daa..3bc1502e42cf 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -826,64 +826,6 @@ static inline void __free_one_page(struct page *page, page_reporting_notify_free(order); }

-/** - * split_free_page() -- split a free page at split_pfn_offset - * @free_page: the original free page - * @order: the order of the page - * @split_pfn_offset: split offset within the page - * - * Return -ENOENT if the free page is changed, otherwise 0 - * - * It is used when the free page crosses two pageblocks with different migratetypes - * at split_pfn_offset within the page. The split free page will be put into - * separate migratetype lists afterwards. Otherwise, the function achieves - * nothing. - */ -int split_free_page(struct page *free_page, - unsigned int order, unsigned long split_pfn_offset) -{ - struct zone *zone = page_zone(free_page); - unsigned long free_page_pfn = page_to_pfn(free_page); - unsigned long pfn; - unsigned long flags; - int free_page_order; - int mt; - int ret = 0; - - if (split_pfn_offset == 0) - return ret; - - spin_lock_irqsave(&zone->lock, flags); - - if (!PageBuddy(free_page) || buddy_order(free_page) != order) { - ret = -ENOENT; - goto out; - } - - mt = get_pfnblock_migratetype(free_page, free_page_pfn); - if (likely(!is_migrate_isolate(mt))) - __mod_zone_freepage_state(zone, -(1UL << order), mt); - - del_page_from_free_list(free_page, zone, order); - for (pfn = free_page_pfn; - pfn < free_page_pfn + (1UL << order);) { - int mt = get_pfnblock_migratetype(pfn_to_page(pfn), pfn); - - free_page_order = min_t(unsigned int, - pfn ? __ffs(pfn) : order, - __fls(split_pfn_offset)); - __free_one_page(pfn_to_page(pfn), pfn, zone, free_page_order, - mt, FPI_NONE); - pfn += 1UL << free_page_order; - split_pfn_offset -= (1UL << free_page_order); - /* we have done the first part, now switch to second part */ - if (split_pfn_offset == 0) - split_pfn_offset = (1UL << order) - (pfn - free_page_pfn); - } -out: - spin_unlock_irqrestore(&zone->lock, flags); - return ret; -} /* * A bad page could be due to a number of fields. Instead of multiple branches, * try and check multiple fields with one check. The caller must do a detailed @@ -1685,8 +1627,8 @@ static bool prep_move_freepages_block(struct zone *zone, struct page *page, return true; }

-int move_freepages_block(struct zone *zone, struct page *page, - int migratetype) +static int move_freepages_block(struct zone *zone, struct page *page, + int migratetype) { unsigned long start_pfn, end_pfn;

@@ -1697,6 +1639,123 @@ int move_freepages_block(struct zone *zone, struct page *page, return move_freepages(zone, start_pfn, end_pfn, migratetype); }

+#ifdef CONFIG_MEMORY_ISOLATION +/* Look for a buddy that straddles start_pfn */ +static unsigned long find_large_buddy(unsigned long start_pfn) +{ + int order = 0; + struct page *page; + unsigned long pfn = start_pfn; + + while (!PageBuddy(page = pfn_to_page(pfn))) { + /* Nothing found */ + if (++order > MAX_PAGE_ORDER) + return start_pfn; + pfn &= ~0UL << order; + } + + /* + * Found a preceding buddy, but does it straddle? + */ + if (pfn + (1 << buddy_order(page)) > start_pfn) + return pfn; + + /* Nothing found */ + return start_pfn; +} + +/* Split a multi-block free page into its individual pageblocks */ +static void split_large_buddy(struct zone *zone, struct page *page, + unsigned long pfn, int order) +{ + unsigned long end_pfn = pfn + (1 << order); + + VM_WARN_ON_ONCE(order <= pageblock_order); + VM_WARN_ON_ONCE(pfn & (pageblock_nr_pages - 1)); + + /* Caller removed page from freelist, buddy info cleared! */ + VM_WARN_ON_ONCE(PageBuddy(page)); + + while (pfn != end_pfn) { + int mt = get_pfnblock_migratetype(page, pfn); + + __free_one_page(page, pfn, zone, pageblock_order, mt, FPI_NONE); + pfn += pageblock_nr_pages; + page = pfn_to_page(pfn); + } +} + +/** + * move_freepages_block_isolate - move free pages in block for page isolation + * @zone: the zone + * @page: the pageblock page + * @migratetype: migratetype to set on the pageblock + * + * This is similar to move_freepages_block(), but handles the special + * case encountered in page isolation, where the block of interest + * might be part of a larger buddy spanning multiple pageblocks. + * + * Unlike the regular page allocator path, which moves pages while + * stealing buddies off the freelist, page isolation is interested in + * arbitrary pfn ranges that may have overlapping buddies on both ends. + * + * This function handles that. Straddling buddies are split into + * individual pageblocks. Only the block of interest is moved. + * + * Returns %true if pages could be moved, %false otherwise. + */ +bool move_freepages_block_isolate(struct zone *zone, struct page *page, + int migratetype) +{ + unsigned long start_pfn, end_pfn, pfn; + int nr_moved, mt; + + if (!prep_move_freepages_block(zone, page, &start_pfn, &end_pfn, + NULL, NULL)) + return false; + + /* No splits needed if buddies can't span multiple blocks */ + if (pageblock_order == MAX_PAGE_ORDER) + goto move; + + /* We're a tail block in a larger buddy */ + pfn = find_large_buddy(start_pfn); + if (pfn != start_pfn) { + struct page *buddy = pfn_to_page(pfn); + int order = buddy_order(buddy); + int mt = get_pfnblock_migratetype(buddy, pfn); + + if (!is_migrate_isolate(mt)) + __mod_zone_freepage_state(zone, -(1UL << order), mt); + del_page_from_free_list(buddy, zone, order); + set_pageblock_migratetype(page, migratetype); + split_large_buddy(zone, buddy, pfn, order); + return true; + } + + /* We're the starting block of a larger buddy */ + if (PageBuddy(page) && buddy_order(page) > pageblock_order) { + int mt = get_pfnblock_migratetype(page, pfn); + int order = buddy_order(page); + + if (!is_migrate_isolate(mt)) + __mod_zone_freepage_state(zone, -(1UL << order), mt); + del_page_from_free_list(page, zone, order); + set_pageblock_migratetype(page, migratetype); + split_large_buddy(zone, page, pfn, order); + return true; + } +move: + mt = get_pfnblock_migratetype(page, start_pfn); + nr_moved = move_freepages(zone, start_pfn, end_pfn, migratetype); + if (!is_migrate_isolate(mt)) + __mod_zone_freepage_state(zone, -nr_moved, mt); + else if (!is_migrate_isolate(migratetype)) + __mod_zone_freepage_state(zone, nr_moved, migratetype); + return true; +} +#endif /* CONFIG_MEMORY_ISOLATION */ + static void change_pageblock_range(struct page *pageblock_page, int start_order, int migratetype) { @@ -6575,7 +6634,6 @@ int alloc_contig_range(unsigned long start, unsigned long end, unsigned migratetype, gfp_t gfp_mask) { unsigned long outer_start, outer_end; - int order; int ret = 0;

struct compact_control cc = { @@ -6648,29 +6706,7 @@ int alloc_contig_range(unsigned long start, unsigned long end, * We don't have to hold zone->lock here because the pages are * isolated thus they won't get removed from buddy. */ - - order = 0; - outer_start = start; - while (!PageBuddy(pfn_to_page(outer_start))) { - if (++order > MAX_ORDER) { - outer_start = start; - break; - } - outer_start &= ~0UL << order; - } - - if (outer_start != start) { - order = buddy_order(pfn_to_page(outer_start)); - - /* - * outer_start page could be small order buddy page and - * it doesn't include start page. Adjust outer_start - * in this case to report failed page properly - * on tracepoint in test_pages_isolated() - */ - if (outer_start + (1UL << order) <= start) - outer_start = start; - } + outer_start = find_large_buddy(start);

/* Make sure the range is really isolated. */ if (test_pages_isolated(outer_start, end, 0)) { diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 8fc4f9491417..b3aae89ed226 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -179,16 +179,10 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ unmovable = has_unmovable_pages(check_unmovable_start, check_unmovable_end, migratetype, isol_flags); if (!unmovable) { - int nr_pages; - int mt = get_pageblock_migratetype(page); - - nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE); - /* Block spans zone boundaries? */ - if (nr_pages == -1) { + if (!move_freepages_block_isolate(zone, page, MIGRATE_ISOLATE)) { spin_unlock_irqrestore(&zone->lock, flags); return -EBUSY; } - __mod_zone_freepage_state(zone, -nr_pages, mt); zone->nr_isolate_pageblock++; spin_unlock_irqrestore(&zone->lock, flags); return 0; @@ -255,13 +249,11 @@ static void unset_migratetype_isolate(struct page *page, int migratetype) * allocation. */ if (!isolated_page) { - int nr_pages = move_freepages_block(zone, page, migratetype); /* * Isolating this block already succeeded, so this * should not fail on zone boundaries. */ - WARN_ON_ONCE(nr_pages == -1); - __mod_zone_freepage_state(zone, nr_pages, migratetype); + WARN_ON_ONCE(!move_freepages_block_isolate(zone, page, migratetype)); } else { set_pageblock_migratetype(page, migratetype); __putback_isolated_page(page, order, migratetype); @@ -377,26 +369,29 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,

VM_BUG_ON(!page); pfn = page_to_pfn(page); - /* - * start_pfn is MAX_ORDER_NR_PAGES aligned, if there is any - * free pages in [start_pfn, boundary_pfn), its head page will - * always be in the range. - */ + if (PageBuddy(page)) { int order = buddy_order(page);

- if (pfn + (1UL << order) > boundary_pfn) { - /* free page changed before split, check it again */ - if (split_free_page(page, order, boundary_pfn - pfn)) - continue; - } + /* move_freepages_block_isolate() handled this */ + VM_WARN_ON_ONCE(pfn + (1 << order) > boundary_pfn);

pfn += 1UL << order; continue; } + /* - * migrate compound pages then let the free page handling code - * above do the rest. If migration is not possible, just fail. + * If a compound page is straddling our block, attempt + * to migrate it out of the way. + * + * We don't have to worry about this creating a large + * free page that straddles into our block: gigantic + * pages are freed as order-0 chunks, and LRU pages + * (currently) do not exceed pageblock_order. + * + * The block of interest has already been marked + * MIGRATE_ISOLATE above, so when migration is done it + * will free its pages onto the correct freelists. */ if (PageCompound(page)) { struct page *head = compound_head(page); @@ -407,16 +402,10 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, pfn = head_pfn + nr_pages; continue; } + #if defined CONFIG_COMPACTION || defined CONFIG_CMA - /* - * hugetlb, lru compound (THP), and movable compound pages - * can be migrated. Otherwise, fail the isolation. - */ - if (PageHuge(page) || PageLRU(page) || __PageMovable(page)) { - int order; - unsigned long outer_pfn; + if (PageHuge(page)) { int page_mt = get_pageblock_migratetype(page); - bool isolate_page = !is_migrate_isolate_page(page); struct compact_control cc = { .nr_migratepages = 0, .order = -1, @@ -429,56 +418,25 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, }; INIT_LIST_HEAD(&cc.migratepages);

- /* - * XXX: mark the page as MIGRATE_ISOLATE so that - * no one else can grab the freed page after migration. - * Ideally, the page should be freed as two separate - * pages to be added into separate migratetype free - * lists. - */ - if (isolate_page) { - ret = set_migratetype_isolate(page, page_mt, - flags, head_pfn, head_pfn + nr_pages); - if (ret) - goto failed; - } - ret = __alloc_contig_migrate_range(&cc, head_pfn, head_pfn + nr_pages, page_mt); - - /* - * restore the page's migratetype so that it can - * be split into separate migratetype free lists - * later. - */ - if (isolate_page) - unset_migratetype_isolate(page, page_mt); - if (ret) goto failed; - /* - * reset pfn to the head of the free page, so - * that the free page handling code above can split - * the free page to the right migratetype list. - * - * head_pfn is not used here as a hugetlb page order - * can be bigger than MAX_ORDER, but after it is - * freed, the free page order is not. Use pfn within - * the range to find the head of the free page. - */ - order = 0; - outer_pfn = pfn; - while (!PageBuddy(pfn_to_page(outer_pfn))) { - /* stop if we cannot find the free page */ - if (++order > MAX_ORDER) - goto failed; - outer_pfn &= ~0UL << order; - } - pfn = outer_pfn; + pfn = head_pfn + nr_pages; continue; - } else + } + + /* + * These pages are movable too, but they're + * not expected to exceed pageblock_order. + * + * Let us know when they do, so we can add + * proper free and split handling for them. + */ + VM_WARN_ON_ONCE_PAGE(PageLRU(page), page); + VM_WARN_ON_ONCE_PAGE(__PageMovable(page), page); #endif - goto failed; + goto failed; }

pfn++;

From: Vlastimil Babka vbabka@suse.cz

mainline inclusion from mainline-v6.10-rc1 commit e1f42a577f63647dadf1abe4583053c03d6be045 category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

The function is now supposed to be called only on a single pageblock and checks start_pfn and end_pfn accordingly. Rename it to make this more obvious and drop the end_pfn parameter which can be determined trivially and none of the callers use it for anything else.

Also make the (now internal) end_pfn exclusive, which is more common.

Link: https://lkml.kernel.org/r/81b1d642-2ec0-49f5-89fc-19a3828419ff@suse.cz Signed-off-by: Vlastimil Babka vbabka@suse.cz Reviewed-by: Zi Yan ziy@nvidia.com Acked-by: Johannes Weiner hannes@cmpxchg.org Cc: David Hildenbrand david@redhat.com Cc: "Huang, Ying" ying.huang@intel.com Cc: Mel Gorman mgorman@techsingularity.net Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_alloc.c | 43 ++++++++++++++++++++----------------------- 1 file changed, 20 insertions(+), 23 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d662bbdf2e91..7270d665fc53 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1571,18 +1571,18 @@ static inline struct page *__rmqueue_cma_fallback(struct zone *zone, * Change the type of a block and move all its free pages to that * type's freelist. */ -static int move_freepages(struct zone *zone, unsigned long start_pfn, - unsigned long end_pfn, int old_mt, int new_mt) +static int __move_freepages_block(struct zone *zone, unsigned long start_pfn, + int old_mt, int new_mt) { struct page *page; - unsigned long pfn; + unsigned long pfn, end_pfn; unsigned int order; int pages_moved = 0;

VM_WARN_ON(start_pfn & (pageblock_nr_pages - 1)); - VM_WARN_ON(start_pfn + pageblock_nr_pages - 1 != end_pfn); + end_pfn = pageblock_end_pfn(start_pfn);

- for (pfn = start_pfn; pfn <= end_pfn;) { + for (pfn = start_pfn; pfn < end_pfn;) { page = pfn_to_page(pfn); if (!PageBuddy(page)) { pfn++; @@ -1608,14 +1608,13 @@ static int move_freepages(struct zone *zone, unsigned long start_pfn,

static bool prep_move_freepages_block(struct zone *zone, struct page *page, unsigned long *start_pfn, - unsigned long *end_pfn, int *num_free, int *num_movable) { unsigned long pfn, start, end;

pfn = page_to_pfn(page); start = pageblock_start_pfn(pfn); - end = pageblock_end_pfn(pfn) - 1; + end = pageblock_end_pfn(pfn);

/* * The caller only has the lock for @zone, don't touch ranges @@ -1626,16 +1625,15 @@ static bool prep_move_freepages_block(struct zone *zone, struct page *page, */ if (!zone_spans_pfn(zone, start)) return false; - if (!zone_spans_pfn(zone, end)) + if (!zone_spans_pfn(zone, end - 1)) return false;

*start_pfn = start; - *end_pfn = end;

if (num_free) { *num_free = 0; *num_movable = 0; - for (pfn = start; pfn <= end;) { + for (pfn = start; pfn < end;) { page = pfn_to_page(pfn); if (PageBuddy(page)) { int nr = 1 << buddy_order(page); @@ -1661,13 +1659,12 @@ static bool prep_move_freepages_block(struct zone *zone, struct page *page, static int move_freepages_block(struct zone *zone, struct page *page, int old_mt, int new_mt) { - unsigned long start_pfn, end_pfn; + unsigned long start_pfn;

- if (!prep_move_freepages_block(zone, page, &start_pfn, &end_pfn, - NULL, NULL)) + if (!prep_move_freepages_block(zone, page, &start_pfn, NULL, NULL)) return -1;

- return move_freepages(zone, start_pfn, end_pfn, old_mt, new_mt); + return __move_freepages_block(zone, start_pfn, old_mt, new_mt); }

#ifdef CONFIG_MEMORY_ISOLATION @@ -1738,10 +1735,9 @@ static void split_large_buddy(struct zone *zone, struct page *page, bool move_freepages_block_isolate(struct zone *zone, struct page *page, int migratetype) { - unsigned long start_pfn, end_pfn, pfn; + unsigned long start_pfn, pfn;

- if (!prep_move_freepages_block(zone, page, &start_pfn, &end_pfn, - NULL, NULL)) + if (!prep_move_freepages_block(zone, page, &start_pfn, NULL, NULL)) return false;

/* No splits needed if buddies can't span multiple blocks */ @@ -1772,8 +1768,9 @@ bool move_freepages_block_isolate(struct zone *zone, struct page *page, return true; } move: - move_freepages(zone, start_pfn, end_pfn, - get_pfnblock_migratetype(page, start_pfn), migratetype); + __move_freepages_block(zone, start_pfn, + get_pfnblock_migratetype(page, start_pfn), + migratetype); return true; } #endif /* CONFIG_MEMORY_ISOLATION */ @@ -1873,7 +1870,7 @@ steal_suitable_fallback(struct zone *zone, struct page *page, unsigned int alloc_flags, bool whole_block) { int free_pages, movable_pages, alike_pages; - unsigned long start_pfn, end_pfn; + unsigned long start_pfn; int block_type;

block_type = get_pageblock_migratetype(page); @@ -1906,8 +1903,8 @@ steal_suitable_fallback(struct zone *zone, struct page *page, goto single_page;

/* moving whole block can fail due to zone boundary conditions */ - if (!prep_move_freepages_block(zone, page, &start_pfn, &end_pfn, - &free_pages, &movable_pages)) + if (!prep_move_freepages_block(zone, page, &start_pfn, &free_pages, + &movable_pages)) goto single_page;

/* @@ -1937,7 +1934,7 @@ steal_suitable_fallback(struct zone *zone, struct page *page, */ if (free_pages + alike_pages >= (1 << (pageblock_order-1)) || page_group_by_mobility_disabled) { - move_freepages(zone, start_pfn, end_pfn, block_type, start_type); + __move_freepages_block(zone, start_pfn, block_type, start_type); return __rmqueue_smallest(zone, order, start_type); }

From: Johannes Weiner hannes@cmpxchg.org

mainline inclusion from mainline-v6.10-rc3 commit 7cc5a5d65011983952a9c62f170f5b79e24b1239 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

Christoph reports a page allocator splat triggered by xfstests:

generic/176 214s ... [ 1204.507931] run fstests generic/176 at 2024-05-27 12:52:30 XFS (nvme0n1): Mounting V5 Filesystem cd936307-415f-48a3-b99d-a2d52ae1f273 XFS (nvme0n1): Ending clean mount XFS (nvme1n1): Mounting V5 Filesystem ab3ee1a4-af62-4934-9a6a-6c2fde321850 XFS (nvme1n1): Ending clean mount XFS (nvme1n1): Unmounting Filesystem ab3ee1a4-af62-4934-9a6a-6c2fde321850 XFS (nvme1n1): Mounting V5 Filesystem 7099b02d-9c58-4d1d-be1d-2cc472d12cd9 XFS (nvme1n1): Ending clean mount ------------[ cut here ]------------ page type is 3, passed migratetype is 1 (nr=512) WARNING: CPU: 0 PID: 509870 at mm/page_alloc.c:645 expand+0x1c5/0x1f0 Modules linked in: i2c_i801 crc32_pclmul i2c_smbus [last unloaded: scsi_debug] CPU: 0 PID: 509870 Comm: xfs_io Not tainted 6.10.0-rc1+ #2437 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:expand+0x1c5/0x1f0 Code: 05 16 70 bf 02 01 e8 ca fc ff ff 8b 54 24 34 44 89 e1 48 c7 c7 80 a2 28 83 48 89 c6 b8 01 00 3 RSP: 0018:ffffc90003b2b968 EFLAGS: 00010082 RAX: 0000000000000000 RBX: ffffffff83fa9480 RCX: 0000000000000000 RDX: 0000000000000005 RSI: 0000000000000027 RDI: 00000000ffffffff RBP: 00000000001f2600 R08: 00000000fffeffff R09: 0000000000000001 R10: 0000000000000000 R11: ffffffff83676200 R12: 0000000000000009 R13: 0000000000000200 R14: 0000000000000001 R15: ffffea0007c98000 FS: 00007f72ca3d5780(0000) GS:ffff8881f9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f72ca1fff38 CR3: 00000001aa0c6002 CR4: 0000000000770ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> ? __warn+0x7b/0x120 ? expand+0x1c5/0x1f0 ? report_bug+0x191/0x1c0 ? handle_bug+0x3c/0x80 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? expand+0x1c5/0x1f0 ? expand+0x1c5/0x1f0 __rmqueue_pcplist+0x3a9/0x730 get_page_from_freelist+0x7a0/0xf00 __alloc_pages_noprof+0x153/0x2e0 __folio_alloc_noprof+0x10/0xa0 __filemap_get_folio+0x16b/0x370 iomap_write_begin+0x496/0x680

While trying to service a movable allocation (page type 1), the page allocator runs into a two-pageblock buddy on the movable freelist whose second block is typed as highatomic (page type 3).

This inconsistency is caused by the highatomic reservation system operating on single pageblocks, while MAX_ORDER can be bigger than that - in this configuration, pageblock_order is 9 while MAX_PAGE_ORDER is 10. The test case is observed to make several adjacent order-3 requests with __GFP_DIRECT_RECLAIM cleared, which marks the surrounding block as highatomic. Upon freeing, the blocks merge into an order-10 buddy. When the highatomic pool is drained later on, this order-10 buddy gets moved back to the movable list, but only the first pageblock is marked movable again. A subsequent expand() of this buddy warns about the tail being of a different type.

This is a long-standing bug that's surfaced by the recent block type warnings added to the allocator. The consequences seem mostly benign, it just results in odd behavior: the highatomic tail blocks are not properly drained, instead they end up on the movable list first, then go back to the highatomic list after an alloc-free cycle.

To fix this, make the highatomic reservation code aware that allocations/buddies can be larger than a pageblock.

While it's an old quirk, the recently added type consistency warnings seem to be the most prominent consequence of it. Set the Fixes: tag accordingly to highlight this backporting dependency.

Link: https://lkml.kernel.org/r/20240530114203.GA1222079@cmpxchg.org Fixes: e0932b6c1f94 ("mm: page_alloc: consolidate free page accounting") Signed-off-by: Johannes Weiner hannes@cmpxchg.org Reported-by: Christoph Hellwig hch@infradead.org Reviewed-by: Zi Yan ziy@nvidia.com Tested-by: Christoph Hellwig hch@lst.de Cc: Andy Shevchenko andriy.shevchenko@linux.intel.com Cc: Baolin Wang baolin.wang@linux.alibaba.com Cc: Mel Gorman mgorman@techsingularity.net Cc: Vlastimil Babka vbabka@suse.cz Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_alloc.c | 50 +++++++++++++++++++++++++++++++++---------------- 1 file changed, 34 insertions(+), 16 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4e2ec54b6a7f..53534165b5ab 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1982,10 +1982,12 @@ int find_suitable_fallback(struct free_area *area, unsigned int order, }

/* - * Reserve a pageblock for exclusive use of high-order atomic allocations if - * there are no empty page blocks that contain a page with a suitable order + * Reserve the pageblock(s) surrounding an allocation request for + * exclusive use of high-order atomic allocations if there are no + * empty page blocks that contain a page with a suitable order */ -static void reserve_highatomic_pageblock(struct page *page, struct zone *zone) +static void reserve_highatomic_pageblock(struct page *page, int order, + struct zone *zone) { int mt; unsigned long max_managed, flags; @@ -2011,10 +2013,17 @@ static void reserve_highatomic_pageblock(struct page *page, struct zone *zone) /* Yoink! */ mt = get_pageblock_migratetype(page); /* Only reserve normal pageblocks (i.e., they can merge with others) */ - if (migratetype_is_mergeable(mt)) - if (move_freepages_block(zone, page, mt, - MIGRATE_HIGHATOMIC) != -1) - zone->nr_reserved_highatomic += pageblock_nr_pages; + if (!migratetype_is_mergeable(mt)) + goto out_unlock; + + if (order < pageblock_order) { + if (move_freepages_block(zone, page, mt, MIGRATE_HIGHATOMIC) == -1) + goto out_unlock; + zone->nr_reserved_highatomic += pageblock_nr_pages; + } else { + change_pageblock_range(page, order, MIGRATE_HIGHATOMIC); + zone->nr_reserved_highatomic += 1 << order; + }

out_unlock: spin_unlock_irqrestore(&zone->lock, flags); @@ -2026,7 +2035,7 @@ static void reserve_highatomic_pageblock(struct page *page, struct zone *zone) * intense memory pressure but failed atomic allocations should be easier * to recover from than an OOM. * - * If @force is true, try to unreserve a pageblock even though highatomic + * If @force is true, try to unreserve pageblocks even though highatomic * pageblock is exhausted. */ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac, @@ -2068,6 +2077,7 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac, * adjust the count once. */ if (is_migrate_highatomic(mt)) { + unsigned long size; /* * It should never happen but changes to * locking could inadvertently allow a per-cpu @@ -2075,9 +2085,9 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac, * while unreserving so be safe and watch for * underflows. */ - zone->nr_reserved_highatomic -= min( - pageblock_nr_pages, - zone->nr_reserved_highatomic); + size = max(pageblock_nr_pages, 1UL << order); + size = min(size, zone->nr_reserved_highatomic); + zone->nr_reserved_highatomic -= size; }

/* @@ -2089,11 +2099,19 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac, * of pageblocks that cannot be completely freed * may increase. */ - ret = move_freepages_block(zone, page, mt, - ac->migratetype); + if (order < pageblock_order) + ret = move_freepages_block(zone, page, mt, + ac->migratetype); + else { + move_to_free_list(page, zone, order, mt, + ac->migratetype); + change_pageblock_range(page, order, + ac->migratetype); + ret = 1; + } /* - * Reserving this block already succeeded, so this should - * not fail on zone boundaries. + * Reserving the block(s) already succeeded, + * so this should not fail on zone boundaries. */ WARN_ON_ONCE(ret == -1); if (ret > 0) { @@ -3440,7 +3458,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, * if the pageblock should be reserved for the future */ if (unlikely(alloc_flags & ALLOC_HIGHATOMIC)) - reserve_highatomic_pageblock(page, zone); + reserve_highatomic_pageblock(page, order, zone);

return page; } else {

From: Kefeng Wang wangkefeng.wang@huawei.com

mainline inclusion from mainline-v6.12-rc1 commit cd5f3193b432cd70cc1c19aba790300dd11ae934 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

The gigantic page size may larger than memory block size, so memory offline always fails in this case after commit b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity"),

offline_pages start_isolate_page_range start_isolate_page_range(isolate_before=true) isolate [isolate_start, isolate_start + pageblock_nr_pages) start_isolate_page_range(isolate_before=false) isolate [isolate_end - pageblock_nr_pages, isolate_end) pageblock __alloc_contig_migrate_range isolate_migratepages_range isolate_migratepages_block isolate_or_dissolve_huge_page if (hstate_is_gigantic(h)) return -ENOMEM;

[ 15.815756] memory offlining [mem 0x3c0000000-0x3c7ffffff] failed due to failure to isolate range

Gigantic PageHuge is bigger than a pageblock, but since it is freed as order-0 pages, its pageblocks after being freed will get to the right free list. There is no need to have special handling code for them in start_isolate_page_range(). For both alloc_contig_range() and memory offline cases, the migration code after start_isolate_page_range() will be able to migrate gigantic PageHuge when possible. Let's clean up start_isolate_page_range() and fix the aforementioned memory offline failure issue all together.

Let's clean up start_isolate_page_range() and fix the aforementioned memory offline failure issue all together.

Link: https://lkml.kernel.org/r/20240820032630.1894770-1-wangkefeng.wang@huawei.co... Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity") Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com Acked-by: David Hildenbrand david@redhat.com Acked-by: Zi Yan ziy@nvidia.com Cc: Matthew Wilcox willy@infradead.org Cc: Oscar Salvador osalvador@suse.de Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_isolation.c | 28 +++------------------------- 1 file changed, 3 insertions(+), 25 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c index b3aae89ed226..cf7f1922fc3e 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -398,30 +398,8 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, unsigned long head_pfn = page_to_pfn(head); unsigned long nr_pages = compound_nr(head);

- if (head_pfn + nr_pages <= boundary_pfn) { - pfn = head_pfn + nr_pages; - continue; - } - -#if defined CONFIG_COMPACTION || defined CONFIG_CMA - if (PageHuge(page)) { - int page_mt = get_pageblock_migratetype(page); - struct compact_control cc = { - .nr_migratepages = 0, - .order = -1, - .zone = page_zone(pfn_to_page(head_pfn)), - .mode = MIGRATE_SYNC, - .ignore_skip_hint = true, - .no_set_skip_hint = true, - .gfp_mask = gfp_flags, - .alloc_contig = true, - }; - INIT_LIST_HEAD(&cc.migratepages); - - ret = __alloc_contig_migrate_range(&cc, head_pfn, - head_pfn + nr_pages, page_mt); - if (ret) - goto failed; + if (head_pfn + nr_pages <= boundary_pfn || + PageHuge(page)) { pfn = head_pfn + nr_pages; continue; } @@ -435,7 +413,7 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags, */ VM_WARN_ON_ONCE_PAGE(PageLRU(page), page); VM_WARN_ON_ONCE_PAGE(__PageMovable(page), page); -#endif + goto failed; }