| Message ID | 7ab3bffebe59fb419234a68dec1e4572a2518563.1678962352.git.baolin.wang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/2] mm: compaction: consider the number of scanning compound pages in isolate fail path | expand |
On Thu, Mar 16, 2023 at 07:06:47PM +0800, Baolin Wang wrote: > When trying to isolate a migratable pageblock, it can contain several > normal pages or several hugetlb pages (e.g. CONT-PTE 64K hugetlb on arm64) > in a pageblock. That means we may hold the lru lock of a normal page to > continue to isolate the next hugetlb page by isolate_or_dissolve_huge_page() > in the same migratable pageblock. > > However in the isolate_or_dissolve_huge_page(), it may allocate a new hugetlb > page and dissolve the old one by alloc_and_dissolve_hugetlb_folio() if the > hugetlb's refcount is zero. That means we can still enter the direct compaction > path to allocate a new hugetlb page under the current lru lock, which > may cause possible deadlock. > > To avoid this possible deadlock, we should release the lru lock when trying > to isolate a hugetbl page. Moreover it does not make sense to take the lru > lock to isolate a hugetlb, which is not in the lru list. > > Fixes: 369fa227c219 ("mm: make alloc_contig_range handle free hugetlb pages") > Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> > Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Mel Gorman <mgorman@techsingularity.net>
diff --git a/mm/compaction.c b/mm/compaction.c index 7e645cdfc2e9..3df076716691 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -894,6 +894,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, } if (PageHuge(page) && cc->alloc_contig) { + if (locked) { + unlock_page_lruvec_irqrestore(locked, flags); + locked = NULL; + } + ret = isolate_or_dissolve_huge_page(page, &cc->migratepages); /*
When trying to isolate a migratable pageblock, it can contain several normal pages or several hugetlb pages (e.g. CONT-PTE 64K hugetlb on arm64) in a pageblock. That means we may hold the lru lock of a normal page to continue to isolate the next hugetlb page by isolate_or_dissolve_huge_page() in the same migratable pageblock. However in the isolate_or_dissolve_huge_page(), it may allocate a new hugetlb page and dissolve the old one by alloc_and_dissolve_hugetlb_folio() if the hugetlb's refcount is zero. That means we can still enter the direct compaction path to allocate a new hugetlb page under the current lru lock, which may cause possible deadlock. To avoid this possible deadlock, we should release the lru lock when trying to isolate a hugetbl page. Moreover it does not make sense to take the lru lock to isolate a hugetlb, which is not in the lru list. Fixes: 369fa227c219 ("mm: make alloc_contig_range handle free hugetlb pages") Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> --- Changes from v1: - Collect reviewed tags. Thanks Mike and Vlastimil. --- mm/compaction.c | 5 +++++ 1 file changed, 5 insertions(+)