[PATCH v12 07/10] secretmem: add memcg accounting

[Shakeel Butt]

On Wed, Nov 25, 2020 at 1:51 AM Mike Rapoport <rppt at kernel.org> wrote:
>
> From: Mike Rapoport <rppt at linux.ibm.com>
>
> Account memory consumed by secretmem to memcg. The accounting is updated
> when the memory is actually allocated and freed.
>
> Signed-off-by: Mike Rapoport <rppt at linux.ibm.com>
> Acked-by: Roman Gushchin <guro at fb.com>
> ---
>  mm/filemap.c   |  3 ++-
>  mm/secretmem.c | 36 +++++++++++++++++++++++++++++++++++-
>  2 files changed, 37 insertions(+), 2 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 249cf489f5df..cf7f1dc9f4b8 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -42,6 +42,7 @@
>  #include <linux/psi.h>
>  #include <linux/ramfs.h>
>  #include <linux/page_idle.h>
> +#include <linux/secretmem.h>
>  #include "internal.h"
>
>  #define CREATE_TRACE_POINTS
> @@ -844,7 +845,7 @@ static noinline int __add_to_page_cache_locked(struct page *page,
>         page->mapping = mapping;
>         page->index = offset;
>
> -       if (!huge) {
> +       if (!huge && !page_is_secretmem(page)) {
>                 error = mem_cgroup_charge(page, current->mm, gfp);
>                 if (error)
>                         goto error;
> diff --git a/mm/secretmem.c b/mm/secretmem.c
> index 52a900a135a5..eb6628390444 100644
> --- a/mm/secretmem.c
> +++ b/mm/secretmem.c
> @@ -18,6 +18,7 @@
>  #include <linux/memblock.h>
>  #include <linux/pseudo_fs.h>
>  #include <linux/secretmem.h>
> +#include <linux/memcontrol.h>
>  #include <linux/set_memory.h>
>  #include <linux/sched/signal.h>
>
> @@ -44,6 +45,32 @@ struct secretmem_ctx {
>
>  static struct cma *secretmem_cma;
>
> +static int secretmem_account_pages(struct page *page, gfp_t gfp, int order)
> +{
> +       int err;
> +
> +       err = memcg_kmem_charge_page(page, gfp, order);
> +       if (err)
> +               return err;
> +
> +       /*
> +        * seceremem caches are unreclaimable kernel allocations, so treat
> +        * them as unreclaimable slab memory for VM statistics purposes
> +        */
> +       mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B,
> +                           PAGE_SIZE << order);

Please use mod_lruvec_page_state() instead, so we get the memcg stats too.

BTW I think secretmem deserves a vmstat entry instead of overloading
NR_SLAB_UNRECLAIMABLE_B.

> +
> +       return 0;
> +}
> +
> +static void secretmem_unaccount_pages(struct page *page, int order)
> +{
> +
> +       mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B,
> +                           -PAGE_SIZE << order);
> +       memcg_kmem_uncharge_page(page, order);
> +}
> +
>  static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp)
>  {
>         unsigned long nr_pages = (1 << PMD_PAGE_ORDER);
> @@ -56,10 +83,14 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp)
>         if (!page)
>                 return -ENOMEM;
>
> -       err = set_direct_map_invalid_noflush(page, nr_pages);
> +       err = secretmem_account_pages(page, gfp, PMD_PAGE_ORDER);
>         if (err)
>                 goto err_cma_release;
>
> +       err = set_direct_map_invalid_noflush(page, nr_pages);
> +       if (err)
> +               goto err_memcg_uncharge;
> +
>         addr = (unsigned long)page_address(page);
>         err = gen_pool_add(pool, addr, PMD_SIZE, NUMA_NO_NODE);
>         if (err)
> @@ -76,6 +107,8 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp)
>          * won't fail
>          */
>         set_direct_map_default_noflush(page, nr_pages);
> +err_memcg_uncharge:
> +       secretmem_unaccount_pages(page, PMD_PAGE_ORDER);
>  err_cma_release:
>         cma_release(secretmem_cma, page, nr_pages);
>         return err;
> @@ -302,6 +335,7 @@ static void secretmem_cleanup_chunk(struct gen_pool *pool,
>         int i;
>
>         set_direct_map_default_noflush(page, nr_pages);
> +       secretmem_unaccount_pages(page, PMD_PAGE_ORDER);
>
>         for (i = 0; i < nr_pages; i++)
>                 clear_highpage(page + i);
> --
> 2.28.0
>