Thread (13 messages) read the whole thread 13 messages, 5 authors, 2021-03-04
STALE1977d REVIEWED: 2 (1M)

Revision v5 of 5 in this series; 2 review trailers.

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[PATCH v5 2/5] hugetlg: Break earlier in add_reservation_in_range() when we can

From: Peter Xu <peterx@redhat.com>
Date: 2021-02-17 23:37:46
Also in: lkml
Subsystem: hugetlb subsystem, memory management, the rest · Maintainers: Muchun Song, Oscar Salvador, Andrew Morton, Linus Torvalds

All the regions maintained in hugetlb reserved map is inclusive on "from" but
exclusive on "to".  We can break earlier even if rg->from==t because it already
means no possible intersection.

This does not need a Fixes in all cases because when it happens (rg->from==t)
we'll not break out of the loop while we should, however the next thing we'd do
is still add the last file_region we'd need and quit the loop in the next
round.  So this change is not a bugfix (since the old code should still run
okay iiuc), but we'd better still touch it up to make it logically sane.

Reviewed-by: Mike Kravetz <redacted>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 mm/hugetlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e302ed715839..2ba4ea4ab46e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -387,7 +387,7 @@ static long add_reservation_in_range(struct resv_map *resv, long f, long t,
 		/* When we find a region that starts beyond our range, we've
 		 * finished.
 		 */
-		if (rg->from > t)
+		if (rg->from >= t)
 			break;
 
 		/* Add an entry for last_accounted_offset -> rg->from, and
-- 
2.26.2

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