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author | 2020-10-15 20:09:35 -0700 | |
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committer | 2020-10-16 11:11:18 -0700 | |
commit | 7fef431be9c9ac255838a9578331567b9dba4477 (patch) | |
tree | 28d1ce3435487359938de68bf9a1a57821d610a3 /mm/page_alloc.c | |
parent | mm/page_alloc: move pages to tail in move_to_free_list() (diff) | |
download | linux-7fef431be9c9ac255838a9578331567b9dba4477.tar.gz linux-7fef431be9c9ac255838a9578331567b9dba4477.tar.bz2 linux-7fef431be9c9ac255838a9578331567b9dba4477.zip |
mm/page_alloc: place pages to tail in __free_pages_core()
__free_pages_core() is used when exposing fresh memory to the buddy during
system boot and when onlining memory in generic_online_page().
generic_online_page() is used in two cases:
1. Direct memory onlining in online_pages().
2. Deferred memory onlining in memory-ballooning-like mechanisms (HyperV
balloon and virtio-mem), when parts of a section are kept
fake-offline to be fake-onlined later on.
In 1, we already place pages to the tail of the freelist. Pages will be
freed to MIGRATE_ISOLATE lists first and moved to the tail of the
freelists via undo_isolate_page_range().
In 2, we currently don't implement a proper rule. In case of virtio-mem,
where we currently always online MAX_ORDER - 1 pages, the pages will be
placed to the HEAD of the freelist - undesireable. While the hyper-v
balloon calls generic_online_page() with single pages, usually it will
call it on successive single pages in a larger block.
The pages are fresh, so place them to the tail of the freelist and avoid
the PCP. In __free_pages_core(), remove the now superflouos call to
set_page_refcounted() and add a comment regarding page initialization and
the refcount.
Note: In 2. we currently don't shuffle. If ever relevant (page shuffling
is usually of limited use in virtualized environments), we might want to
shuffle after a sequence of generic_online_page() calls in the relevant
callers.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Link: https://lkml.kernel.org/r/20201005121534.15649-5-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r-- | mm/page_alloc.c | 33 |
1 files changed, 23 insertions, 10 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ea7b697bcf6c..3b032dac62e6 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -275,7 +275,8 @@ bool pm_suspended_storage(void) unsigned int pageblock_order __read_mostly; #endif -static void __free_pages_ok(struct page *page, unsigned int order); +static void __free_pages_ok(struct page *page, unsigned int order, + fpi_t fpi_flags); /* * results with 256, 32 in the lowmem_reserve sysctl: @@ -687,7 +688,7 @@ out: void free_compound_page(struct page *page) { mem_cgroup_uncharge(page); - __free_pages_ok(page, compound_order(page)); + __free_pages_ok(page, compound_order(page), FPI_NONE); } void prep_compound_page(struct page *page, unsigned int order) @@ -1423,14 +1424,14 @@ static void free_pcppages_bulk(struct zone *zone, int count, static void free_one_page(struct zone *zone, struct page *page, unsigned long pfn, unsigned int order, - int migratetype) + int migratetype, fpi_t fpi_flags) { spin_lock(&zone->lock); if (unlikely(has_isolate_pageblock(zone) || is_migrate_isolate(migratetype))) { migratetype = get_pfnblock_migratetype(page, pfn); } - __free_one_page(page, pfn, zone, order, migratetype, FPI_NONE); + __free_one_page(page, pfn, zone, order, migratetype, fpi_flags); spin_unlock(&zone->lock); } @@ -1508,7 +1509,8 @@ void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end) } } -static void __free_pages_ok(struct page *page, unsigned int order) +static void __free_pages_ok(struct page *page, unsigned int order, + fpi_t fpi_flags) { unsigned long flags; int migratetype; @@ -1520,7 +1522,8 @@ static void __free_pages_ok(struct page *page, unsigned int order) migratetype = get_pfnblock_migratetype(page, pfn); local_irq_save(flags); __count_vm_events(PGFREE, 1 << order); - free_one_page(page_zone(page), page, pfn, order, migratetype); + free_one_page(page_zone(page), page, pfn, order, migratetype, + fpi_flags); local_irq_restore(flags); } @@ -1530,6 +1533,11 @@ void __free_pages_core(struct page *page, unsigned int order) struct page *p = page; unsigned int loop; + /* + * When initializing the memmap, __init_single_page() sets the refcount + * of all pages to 1 ("allocated"/"not free"). We have to set the + * refcount of all involved pages to 0. + */ prefetchw(p); for (loop = 0; loop < (nr_pages - 1); loop++, p++) { prefetchw(p + 1); @@ -1540,8 +1548,12 @@ void __free_pages_core(struct page *page, unsigned int order) set_page_count(p, 0); atomic_long_add(nr_pages, &page_zone(page)->managed_pages); - set_page_refcounted(page); - __free_pages(page, order); + + /* + * Bypass PCP and place fresh pages right to the tail, primarily + * relevant for memory onlining. + */ + __free_pages_ok(page, order, FPI_TO_TAIL); } #ifdef CONFIG_NEED_MULTIPLE_NODES @@ -3168,7 +3180,8 @@ static void free_unref_page_commit(struct page *page, unsigned long pfn) */ if (migratetype >= MIGRATE_PCPTYPES) { if (unlikely(is_migrate_isolate(migratetype))) { - free_one_page(zone, page, pfn, 0, migratetype); + free_one_page(zone, page, pfn, 0, migratetype, + FPI_NONE); return; } migratetype = MIGRATE_MOVABLE; @@ -4991,7 +5004,7 @@ static inline void free_the_page(struct page *page, unsigned int order) if (order == 0) /* Via pcp? */ free_unref_page(page); else - __free_pages_ok(page, order); + __free_pages_ok(page, order, FPI_NONE); } void __free_pages(struct page *page, unsigned int order) |