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authorBaolin Wang <baolin.wang@linux.alibaba.com>2023-03-16 19:06:47 +0800
committerAndrew Morton <akpm@linux-foundation.org>2023-04-05 19:42:50 -0700
commit1c06b6a599b5b7be74a6baffafa00b0f70cbe523 (patch)
treeaed24bb201db0eef17bda869537ac711bd8ee356 /mm/compaction.c
parent56d48d8dbefb1cae3aeae54284f7d6f52a41ec23 (diff)
mm: compaction: fix the possible deadlock when isolating hugetlb pages
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. Link: https://lkml.kernel.org/r/7ab3bffebe59fb419234a68dec1e4572a2518563.1678962352.git.baolin.wang@linux.alibaba.com 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> Cc: Oscar Salvador <osalvador@suse.de> Cc: William Lam <william.lam@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/compaction.c')
-rw-r--r--mm/compaction.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 0bddf869bbeb..e689d66cedf4 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);
/*