2023-08-04 03:58:36

by Kemeng Shi

Subject: [PATCH v3 4/8] mm/compaction: correct comment of fast_find_migrateblock in isolate_migratepages

After 90ed667c03fe5 ("Revert "Revert "mm/compaction: fix set skip in
fast_find_migrateblock"""), we remove skip set in fast_find_migrateblock.
Correct comment that fast_find_block is used to avoid isolation_suitable
check for pageblock returned from fast_find_migrateblock because
fast_find_migrateblock will mark found pageblock skipped.
Instead, comment that fast_find_block is used to avoid a redundant check
of fast found pageblock which is already checked skip flag inside
fast_find_migrateblock.

Signed-off-by: Kemeng Shi <[email protected]>
---
mm/compaction.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 9a2f0bd5394a..4bf2dc936add 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1988,9 +1988,9 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc)
block_start_pfn = cc->zone->zone_start_pfn;

/*
- * fast_find_migrateblock marks a pageblock skipped so to avoid
- * the isolation_suitable check below, check whether the fast
- * search was successful.
+ * fast_find_migrateblock() has already ensured the pageblock is not
+ * set with a skipped flag, so to avoid the isolation_suitable check
+ * below again, check whether the fast search was successful.
*/
fast_find_block = low_pfn != cc->migrate_pfn && !cc->fast_search_fail;

--
2.30.0

2023-08-07 09:58:16

by Baolin Wang

Subject: Re: [PATCH v3 4/8] mm/compaction: correct comment of fast_find_migrateblock in isolate_migratepages

On 8/4/2023 7:04 PM, Kemeng Shi wrote:
> After 90ed667c03fe5 ("Revert "Revert "mm/compaction: fix set skip in
> fast_find_migrateblock"""), we remove skip set in fast_find_migrateblock.
> Correct comment that fast_find_block is used to avoid isolation_suitable
> check for pageblock returned from fast_find_migrateblock because
> fast_find_migrateblock will mark found pageblock skipped.
> Instead, comment that fast_find_block is used to avoid a redundant check
> of fast found pageblock which is already checked skip flag inside
> fast_find_migrateblock.
>
> Signed-off-by: Kemeng Shi <[email protected]>

LGTM.
Reviewed-by: Baolin Wang <[email protected]>

> ---
> mm/compaction.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 9a2f0bd5394a..4bf2dc936add 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -1988,9 +1988,9 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc)
> block_start_pfn = cc->zone->zone_start_pfn;
>
> /*
> - * fast_find_migrateblock marks a pageblock skipped so to avoid
> - * the isolation_suitable check below, check whether the fast
> - * search was successful.
> + * fast_find_migrateblock() has already ensured the pageblock is not
> + * set with a skipped flag, so to avoid the isolation_suitable check
> + * below again, check whether the fast search was successful.
> */
> fast_find_block = low_pfn != cc->migrate_pfn && !cc->fast_search_fail;
>