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authorDavid Hildenbrand <david@redhat.com>2020-10-15 20:09:35 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-16 11:11:18 -0700
commit7fef431be9c9ac255838a9578331567b9dba4477 (patch)
tree28d1ce3435487359938de68bf9a1a57821d610a3
parent293ffa5ebb9c08a77d8de458166c31b4d7b0cd65 (diff)
downloadlinux-7fef431be9c9ac255838a9578331567b9dba4477.tar.bz2
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>
-rw-r--r--mm/page_alloc.c33
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)