The patch titled
Subject: thp: limit number of object to scan on deferred_split_scan()
has been added to the -mm tree. Its filename is
thp-limit-number-of-object-to-scan-on-deferred_split_scan.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/thp-limit-number-of-object-to-scan-on-deferred_split_scan.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/thp-limit-number-of-object-to-scan-on-deferred_split_scan.patch
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From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: thp: limit number of object to scan on deferred_split_scan()
If we have a lot of pages in queue to be split, deferred_split_scan()
can spend unreasonable amount of time under spinlock with disabled
interrupts.
Let's cap number of pages to split on scan by sc->nr_to_scan.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reported-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Jerome Marchand <jmarchan@xxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff -puN mm/huge_memory.c~thp-limit-number-of-object-to-scan-on-deferred_split_scan mm/huge_memory.c
--- a/mm/huge_memory.c~thp-limit-number-of-object-to-scan-on-deferred_split_scan
+++ a/mm/huge_memory.c
@@ -3478,17 +3478,19 @@ static unsigned long deferred_split_scan
int split = 0;
spin_lock_irqsave(&pgdata->split_queue_lock, flags);
- list_splice_init(&pgdata->split_queue, &list);
-
/* Take pin on all head pages to avoid freeing them under us */
list_for_each_safe(pos, next, &list) {
page = list_entry((void *)pos, struct page, mapping);
page = compound_head(page);
- /* race with put_compound_page() */
- if (!get_page_unless_zero(page)) {
+ if (get_page_unless_zero(page)) {
+ list_move(page_deferred_list(page), &list);
+ } else {
+ /* We lost race with put_compound_page() */
list_del_init(page_deferred_list(page));
pgdata->split_queue_len--;
}
+ if (!--sc->nr_to_scan)
+ break;
}
spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
mm-softirq-safe-softirq-unsafe-lock-order-detected-in-split_huge_page_to_list.patch
mm-proc-add-workaround-for-old-compilers.patch
thp-change-pmd_trans_huge_lock-interface-to-return-ptl.patch
mlocked-pages-statistics-shows-bogus-value.patch
thp-make-split_queue-per-node.patch
thp-change-deferred_split_count-to-return-number-of-thp-in-queue.patch
thp-limit-number-of-object-to-scan-on-deferred_split_scan.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-2.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-3.patch
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