lkml.org 
[lkml]   [2018]   [Jul]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v3 bpf-next 01/14] bpf: add ability to charge bpf maps memory dynamically
From
Date
On 07/20/2018 07:45 PM, Roman Gushchin wrote:
> This commits extends existing bpf maps memory charging API
> to support dynamic charging/uncharging.
>
> This is required to account memory used by maps,
> if all entries are created dynamically after
> the map initialization.
>
> Signed-off-by: Roman Gushchin <guro@fb.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Acked-by: Martin KaFai Lau <kafai@fb.com>
> ---
> include/linux/bpf.h | 2 ++
> kernel/bpf/syscall.c | 53 +++++++++++++++++++++++++++++++++++++---------------
> 2 files changed, 40 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 5b5ad95cf339..5a4a256473c3 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -435,6 +435,8 @@ struct bpf_map * __must_check bpf_map_inc(struct bpf_map *map, bool uref);
> void bpf_map_put_with_uref(struct bpf_map *map);
> void bpf_map_put(struct bpf_map *map);
> int bpf_map_precharge_memlock(u32 pages);
> +int bpf_map_charge_memlock(struct bpf_map *map, u32 pages);
> +void bpf_map_uncharge_memlock(struct bpf_map *map, u32 pages);
> void *bpf_map_area_alloc(size_t size, int numa_node);
> void bpf_map_area_free(void *base);
> void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr);
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index d10ecd78105f..cee452a19538 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -181,32 +181,55 @@ int bpf_map_precharge_memlock(u32 pages)
> return 0;
> }
>
> -static int bpf_map_charge_memlock(struct bpf_map *map)
> +static int bpf_charge_memlock(struct user_struct *user, u32 pages)
> {
> - struct user_struct *user = get_current_user();
> - unsigned long memlock_limit;
> + unsigned long memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
>
> - memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> + if (atomic_long_add_return(pages, &user->locked_vm) > memlock_limit) {
> + atomic_long_sub(pages, &user->locked_vm);
> + return -EPERM;
> + }
> + return 0;
> +}
>
> - atomic_long_add(map->pages, &user->locked_vm);
> +static int bpf_map_init_memlock(struct bpf_map *map)
> +{
> + struct user_struct *user = get_current_user();
> + int ret;
>
> - if (atomic_long_read(&user->locked_vm) > memlock_limit) {
> - atomic_long_sub(map->pages, &user->locked_vm);
> + ret = bpf_charge_memlock(user, map->pages);
> + if (ret) {
> free_uid(user);
> - return -EPERM;
> + return ret;
> }
> map->user = user;
> - return 0;
> + return ret;
> }
>
> -static void bpf_map_uncharge_memlock(struct bpf_map *map)
> +static void bpf_map_release_memlock(struct bpf_map *map)
> {
> struct user_struct *user = map->user;
> -
> - atomic_long_sub(map->pages, &user->locked_vm);
> + atomic_long_sub(map->pages, &map->user->locked_vm);

Just a small nit since you're respinning anyway, could you also make a
proper destructor for the bpf_charge_memlock(), so we have a bpf_uncharge_memlock()
which this one here would be calling as well as ...

> free_uid(user);
> }
>
> +int bpf_map_charge_memlock(struct bpf_map *map, u32 pages)
> +{
> + int ret;
> +
> + ret = bpf_charge_memlock(map->user, pages);
> + if (ret)
> + return ret;
> + map->pages += pages;
> + return ret;
> +}
> +
> +void bpf_map_uncharge_memlock(struct bpf_map *map, u32 pages)
> +{
> + atomic_long_sub(pages, &map->user->locked_vm);

... this one, so we hide the details there.

> + map->pages -= pages;
> +}
> +
> static int bpf_map_alloc_id(struct bpf_map *map)
> {
> int id;
> @@ -256,7 +279,7 @@ static void bpf_map_free_deferred(struct work_struct *work)
> {
> struct bpf_map *map = container_of(work, struct bpf_map, work);
>
> - bpf_map_uncharge_memlock(map);
> + bpf_map_release_memlock(map);
> security_bpf_map_free(map);
> /* implementation dependent freeing */
> map->ops->map_free(map);
> @@ -492,7 +515,7 @@ static int map_create(union bpf_attr *attr)
> if (err)
> goto free_map_nouncharge;
>
> - err = bpf_map_charge_memlock(map);
> + err = bpf_map_init_memlock(map);
> if (err)
> goto free_map_sec;
>
> @@ -515,7 +538,7 @@ static int map_create(union bpf_attr *attr)
> return err;
>
> free_map:
> - bpf_map_uncharge_memlock(map);
> + bpf_map_release_memlock(map);
> free_map_sec:
> security_bpf_map_free(map);
> free_map_nouncharge:
>

\
 
 \ /
  Last update: 2018-07-27 20:02    [W:0.211 / U:4.604 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site