On Tue, Feb 9, 2021 at 12:43 PM Roman Gushchin [off-list ref] wrote:

On Tue, Feb 09, 2021 at 09:46:38AM -0800, Yang Shi wrote:

quoted

Both memcg_shrinker_map_size and shrinker_nr_max is maintained, but actually the
map size can be calculated via shrinker_nr_max, so it seems unnecessary to keep both.
Remove memcg_shrinker_map_size since shrinker_nr_max is also used by iterating the
bit map.

Acked-by: Kirill Tkhai <redacted>
Signed-off-by: Yang Shi <redacted>
---
 mm/vmscan.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index e4ddaaaeffe2..641077b09e5d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c

@@ -185,8 +185,10 @@ static LIST_HEAD(shrinker_list);
 static DECLARE_RWSEM(shrinker_rwsem);

 #ifdef CONFIG_MEMCG
+static int shrinker_nr_max;

-static int memcg_shrinker_map_size;
+#define NR_MAX_TO_SHR_MAP_SIZE(nr_max) \
+     (DIV_ROUND_UP(nr_max, BITS_PER_LONG) * sizeof(unsigned long))

How about something like this?

static inline int shrinker_map_size(int nr_items)
{
        return DIV_ROUND_UP(nr_items, BITS_PER_LONG) * sizeof(unsigned long);
}

I think it look less cryptic.

OK, I don't have a strong opinion for either one (inline function or
macro). If no one objects this I could do it in the new version.

The rest of the patch looks good to me.

Thanks!