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| author | SeongJae Park <sj@kernel.org> | 2026-05-22 08:40:13 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-06-04 14:45:00 -0700 |
| commit | b23dbda659b645482e3234ad10773d991a288e2f (patch) | |
| tree | c8f5bfedbd97d9f0e9a65dd7c95d0460454685f3 | |
| parent | ce71e5aa8dc83e703a5301644cef57dfc3caaf44 (diff) | |
| download | linux-b23dbda659b645482e3234ad10773d991a288e2f.tar.gz linux-b23dbda659b645482e3234ad10773d991a288e2f.zip | |
mm/damon/core: do not use region out of a loop in damon_set_regions()
damon_set_regions() assumes the DAMON region iterator is referencing the
last region after the region iteration loop is completed. The code is
indeed implemented in the way, but that is not a documented safe behavior.
Hence it is unreliable and difficult to read. Cleanup the code to avoid
the case.
No behavioral change is intended.
Link: https://lore.kernel.org/20260522154026.80546-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/damon/core.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/damon/core.c b/mm/damon/core.c index 8360cb4c506e..c9946ac8e279 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -374,6 +374,7 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, for (i = 0; i < nr_ranges; i++) { struct damon_region *first = NULL, *last, *newr; struct damon_addr_range *range; + bool insert_before_r = false; range = &ranges[i]; /* Get the first/last regions intersecting with the range */ @@ -383,8 +384,10 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, first = r; last = r; } - if (r->ar.start >= range->end) + if (r->ar.start >= range->end) { + insert_before_r = true; break; + } } if (!first) { /* no region intersects with this range */ @@ -394,7 +397,11 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, ALIGN(range->end, min_region_sz)); if (!newr) return -ENOMEM; - damon_insert_region(newr, damon_prev_region(r), r, t); + if (insert_before_r) + damon_insert_region(newr, damon_prev_region(r), + r, t); + else + damon_add_region(newr, t); } else { /* resize intersecting regions to fit in this range */ first->ar.start = ALIGN_DOWN(range->start, |