Re: [PATCH] mm/vmscan.c: drop all inode/dentry cache from LRU

[Yafang Shao]

On Fri, May 24, 2019 at 4:06 PM Sahitya Tummala <stummala@xxxxxxxxxxxxxx> wrote:
>
> This is important for the scenario where FBE (file based encryption)
> is enabled. With FBE, the encryption context needed to en/decrypt a file
> will be stored in inode and any inode that is left in the cache after
> drop_caches is done will be a problem. For ex, in Android, drop_caches
> will be used when switching work profiles.
>
> Signed-off-by: Sahitya Tummala <stummala@xxxxxxxxxxxxxx>
> ---
>  mm/vmscan.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index d96c547..b48926f 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -730,7 +730,7 @@ void drop_slab_node(int nid)
>                 do {
>                         freed += shrink_slab(GFP_KERNEL, nid, memcg, 0);
>                 } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
> -       } while (freed > 10);
> +       } while (freed != 0);
>  }

Perhaps that is not enough, because the shrink may stop when scan
count is less than SHRINK_BATCH.
Pls. see do_shrink_slab.

What about set shrinker->batch to 1 in this case ?

Thanks
Yafang