2021-07-27 05:39:04

by Vasily Averin

Subject: [PATCH v7 08/10] memcg: enable accounting for posix_timers_cache slab

A program may create multiple interval timers using timer_create().
For each timer the kernel preallocates a "queued real-time signal",
Consequently, the number of timers is limited by the RLIMIT_SIGPENDING
resource limit. The allocated object is quite small, ~250 bytes,
but even the default signal limits allow to consume up to 100 megabytes
per user.

It makes sense to account for them to limit the host's memory consumption
from inside the memcg-limited container.

Signed-off-by: Vasily Averin <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
---
kernel/time/posix-timers.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index dd5697d..7363f81 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -273,8 +273,8 @@ static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
static __init int init_posix_timers(void)
{
posix_timers_cache = kmem_cache_create("posix_timers_cache",
- sizeof (struct k_itimer), 0, SLAB_PANIC,
- NULL);
+ sizeof(struct k_itimer), 0,
+ SLAB_PANIC | SLAB_ACCOUNT, NULL);
return 0;
}
__initcall(init_posix_timers);
--
1.8.3.1

2021-07-27 22:35:26

by Shakeel Butt

Subject: Re: [PATCH v7 08/10] memcg: enable accounting for posix_timers_cache slab

On Mon, Jul 26, 2021 at 10:34 PM Vasily Averin <[email protected]> wrote:
>
> A program may create multiple interval timers using timer_create().
> For each timer the kernel preallocates a "queued real-time signal",
> Consequently, the number of timers is limited by the RLIMIT_SIGPENDING
> resource limit. The allocated object is quite small, ~250 bytes,
> but even the default signal limits allow to consume up to 100 megabytes
> per user.
>
> It makes sense to account for them to limit the host's memory consumption
> from inside the memcg-limited container.
>
> Signed-off-by: Vasily Averin <[email protected]>
> Reviewed-by: Thomas Gleixner <[email protected]>

Reviewed-by: Shakeel Butt <[email protected]>