Re: [PATCH v9 6/9] secretmem: add memcg accounting

Roman Gushchin
2020-11-17T19:38:31Z

On Tue, Nov 17, 2020 at 06:29:29PM +0200, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@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@linux.ibm.com>

Hi Mike!

I like this version so much more, thank you for fixing it.
Please, feel free to add
Acked-by: Roman Gushchin <guro@fb.com> .

Thanks!

> ---
> 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 d4c44fc568a4..abf6ecdf70cb 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>
>
> @@ -50,6 +51,32 @@ 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
^^^^^^^^^
secretmem?

> + * them as unreclaimable slab memory for VM statistics purposes
> + */
> + mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B,
> + PAGE_SIZE << order);
> +
> + 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);
> @@ -62,10 +89,14 @@ 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)
> @@ -82,6 +113,8 @@ 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;
> @@ -312,6 +345,7 @@ 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
>