2021-04-28 17:35:14

by Yu Xu

Subject: [PATCH] mm, compaction: avoid isolating pinned tmpfs pages

This makes pinned tmpfs pages bail out early in the process of page
migration, like what pinned anonymous pages do.

Signed-off-by: Xu Yu <[email protected]>
---
mm/compaction.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index e04f4476e68e..78c3b992a1c9 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -964,11 +964,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
}

/*
- * Migration will fail if an anonymous page is pinned in memory,
- * so avoid taking lru_lock and isolating it unnecessarily in an
- * admittedly racy check.
+ * Migration will fail if an anonymous or tmpfs page is pinned
+ * in memory, so avoid taking lru_lock and isolating it
+ * unnecessarily in an admittedly racy check.
*/
- if (!page_mapping(page) &&
+ if (!page_is_file_lru(page) &&
page_count(page) > page_mapcount(page))
goto isolate_fail;

--
2.20.1.2432.ga663e714

2021-04-28 18:11:39

by Yu Xu

Subject: Re: [PATCH] mm, compaction: avoid isolating pinned tmpfs pages

On 4/28/21 10:00 PM, Xu Yu wrote:
> This makes pinned tmpfs pages bail out early in the process of page
> migration, like what pinned anonymous pages do.
>
> Signed-off-by: Xu Yu <[email protected]>
> ---
> mm/compaction.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index e04f4476e68e..78c3b992a1c9 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -964,11 +964,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> }
>
> /*
> - * Migration will fail if an anonymous page is pinned in memory,
> - * so avoid taking lru_lock and isolating it unnecessarily in an
> - * admittedly racy check.
> + * Migration will fail if an anonymous or tmpfs page is pinned
> + * in memory, so avoid taking lru_lock and isolating it
> + * unnecessarily in an admittedly racy check.
> */
> - if (!page_mapping(page) &&
> + if (!page_is_file_lru(page) &&
> page_count(page) > page_mapcount(page))
Sorry, this patch is flawed, since tmpfs page cache takes an extra page
count.

Please ignore this patch.

> goto isolate_fail;
>
>

--
Thanks,
Yu