From: Josh Law Add a kernel-doc-like comment to damos_commit_dests() documenting its allocation failure contract: on -ENOMEM, the destination structure is left in a partially torn-down state that is safe to deallocate via damon_destroy_scheme(), but must not be reused for further commits. This was unclear from the code alone and led to a separate patch [1] attempting to reset nr_dests on failure. Make the intended usage explicit so future readers do not repeat the confusion. [1] https://lore.kernel.org/20260318214939.36100-1-objecting@objecting.org Signed-off-by: Josh Law Cc: Andrew Morton Reviewed-by: SeongJae Park Signed-off-by: SeongJae Park --- Changes from v1 (https://lore.kernel.org/20260319071332.114595-1-objecting@objecting.org) - Use kernel-doc like comment instead of kernel-doc for static function. - Add a link to the previous discussion. - Update description. - Rebase to latest mm-new. - Collect Reviewed-by: of SJ. mm/damon/core.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 4dae03a37f9ac..df9f5e94e0ddd 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -1060,6 +1060,23 @@ static void damos_set_filters_default_reject(struct damos *s) damos_filters_default_reject(&s->ops_filters); } +/* + * damos_commit_dests() - Copy migration destinations from @src to @dst. + * @dst: Destination structure to update. + * @src: Source structure to copy from. + * + * If the number of destinations has changed, the old arrays in @dst are freed + * and new ones are allocated. On success, @dst contains a full copy of + * @src's arrays and count. + * + * On allocation failure, @dst is left in a partially torn-down state: its + * arrays may be NULL and @nr_dests may not reflect the actual allocation + * sizes. The structure remains safe to deallocate via damon_destroy_scheme(), + * but callers must not reuse @dst for further commits — it should be + * discarded. + * + * Return: 0 on success, -ENOMEM on allocation failure. + */ static int damos_commit_dests(struct damos_migrate_dests *dst, struct damos_migrate_dests *src) { base-commit: 4fbbbf18fd43c2d7b692749b7c853157f901b709 -- 2.47.3