diff options
| author | Gavin Shan <gshan@redhat.com> | 2022-11-24 17:55:23 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-11-30 14:49:41 -0800 |
| commit | 829ae0f81ce093d674ff2256f66a714753e9ce32 (patch) | |
| tree | ab3125d823307a8246a51cb411b4c12600f244f7 | |
| parent | 4aaf269c768dbacd6268af73fda2ffccaa3f1d88 (diff) | |
| download | linux-loongson-829ae0f81ce093d674ff2256f66a714753e9ce32.tar.gz | |
mm: migrate: fix THP's mapcount on isolation
The issue is reported when removing memory through virtio_mem device. The
transparent huge page, experienced copy-on-write fault, is wrongly
regarded as pinned. The transparent huge page is escaped from being
isolated in isolate_migratepages_block(). The transparent huge page can't
be migrated and the corresponding memory block can't be put into offline
state.
Fix it by replacing page_mapcount() with total_mapcount(). With this, the
transparent huge page can be isolated and migrated, and the memory block
can be put into offline state. Besides, The page's refcount is increased
a bit earlier to avoid the page is released when the check is executed.
Link: https://lkml.kernel.org/r/20221124095523.31061-1-gshan@redhat.com
Fixes: 1da2f328fa64 ("mm,thp,compaction,cma: allow THP migration for CMA allocations")
Signed-off-by: Gavin Shan <gshan@redhat.com>
Reported-by: Zhenyu Zhang <zhenyzha@redhat.com>
Tested-by: Zhenyu Zhang <zhenyzha@redhat.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org> [5.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/compaction.c | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/mm/compaction.c b/mm/compaction.c index c51f7f545afe9..1f6da31dd9a50 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -985,28 +985,28 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, } /* + * Be careful not to clear PageLRU until after we're + * sure the page is not being freed elsewhere -- the + * page release code relies on it. + */ + if (unlikely(!get_page_unless_zero(page))) + goto isolate_fail; + + /* * Migration will fail if an anonymous page is pinned in memory, * so avoid taking lru_lock and isolating it unnecessarily in an * admittedly racy check. */ mapping = page_mapping(page); - if (!mapping && page_count(page) > page_mapcount(page)) - goto isolate_fail; + if (!mapping && (page_count(page) - 1) > total_mapcount(page)) + goto isolate_fail_put; /* * Only allow to migrate anonymous pages in GFP_NOFS context * because those do not depend on fs locks. */ if (!(cc->gfp_mask & __GFP_FS) && mapping) - goto isolate_fail; - - /* - * Be careful not to clear PageLRU until after we're - * sure the page is not being freed elsewhere -- the - * page release code relies on it. - */ - if (unlikely(!get_page_unless_zero(page))) - goto isolate_fail; + goto isolate_fail_put; /* Only take pages on LRU: a check now makes later tests safe */ if (!PageLRU(page)) |