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authorZi Yan <ziy@nvidia.com>2022-05-26 19:15:31 -0400
committerakpm <akpm@linux-foundation.org>2022-05-27 09:33:43 -0700
commit86d28b0709279ccc636ef9ba267b7f3bcef79a4b (patch)
tree3d9a9a1eb1b438d7d01b6754540a4f25598658f0 /mm
parent9b209e557d698f24317d2619d8628b98b6728e4f (diff)
downloadlinux-86d28b0709279ccc636ef9ba267b7f3bcef79a4b.tar.bz2
mm: split free page with properly free memory accounting and without race
In isolate_single_pageblock(), free pages are checked without holding zone lock, but they can go away in split_free_page() when zone lock is held. Check the free page and its order again in split_free_page() when zone lock is held. Recheck the page if the free page is gone under zone lock. In addition, in split_free_page(), the free page was deleted from the page list without changing free page accounting. Add the missing free page accounting code. Fix the type of order parameter in split_free_page(). Link: https://lore.kernel.org/lkml/20220525103621.987185e2ca0079f7b97b856d@linux-foundation.org/ Link: https://lkml.kernel.org/r/20220526231531.2404977-2-zi.yan@sent.com Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity") Signed-off-by: Zi Yan <ziy@nvidia.com> Reported-by: Doug Berger <opendmb@gmail.com> Link: https://lore.kernel.org/linux-mm/c3932a6f-77fe-29f7-0c29-fe6b1c67ab7b@gmail.com/ Cc: David Hildenbrand <david@redhat.com> Cc: Qian Cai <quic_qiancai@quicinc.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Eric Ren <renzhengeek@gmail.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michael Walle <michael@walle.cc> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/internal.h4
-rw-r--r--mm/page_alloc.c24
-rw-r--r--mm/page_isolation.c10
3 files changed, 29 insertions, 9 deletions
diff --git a/mm/internal.h b/mm/internal.h
index 64e61b032dac..c0f8fbe0445b 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -374,8 +374,8 @@ extern void *memmap_alloc(phys_addr_t size, phys_addr_t align,
phys_addr_t min_addr,
int nid, bool exact_nid);
-void split_free_page(struct page *free_page,
- int order, unsigned long split_pfn_offset);
+int split_free_page(struct page *free_page,
+ unsigned int order, unsigned long split_pfn_offset);
#if defined CONFIG_COMPACTION || defined CONFIG_CMA
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bc93a82e51e6..6f6e4649ac21 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1100,30 +1100,44 @@ done_merging:
* @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.
*/
-void split_free_page(struct page *free_page,
- int order, unsigned long split_pfn_offset)
+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;
+ return ret;
spin_lock_irqsave(&zone->lock, flags);
+
+ if (!PageBuddy(free_page) || buddy_order(free_page) != order) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ mt = get_pageblock_migratetype(free_page);
+ 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(int,
+ 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,
@@ -1134,7 +1148,9 @@ void split_free_page(struct page *free_page,
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,
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index fbd820b21292..6021f8444b5a 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -371,9 +371,13 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
if (PageBuddy(page)) {
int order = buddy_order(page);
- if (pfn + (1UL << order) > boundary_pfn)
- split_free_page(page, order, boundary_pfn - pfn);
- pfn += (1UL << order);
+ if (pfn + (1UL << order) > boundary_pfn) {
+ /* free page changed before split, check it again */
+ if (split_free_page(page, order, boundary_pfn - pfn))
+ continue;
+ }
+
+ pfn += 1UL << order;
continue;
}
/*