On Tue, Nov 05, 2024 at 11:10:24AM +0800, Yun Zhou wrote:
> It is necessary to have a different pid_max in different containers.
> For example, multiple containers are running on a host, one of which
> is Android, and its 32 bit bionic libc only accepts pid <= 65535. So
> it requires the global pid_max <= 65535. This will cause configuration
> conflicts with other containers and also limit the maximum number of
> tasks for the entire system.
>
> Signed-off-by: Yun Zhou <yun.z...@windriver.com>
> ---
> - Remove sentinels from ctl_table arrays.
> v1 -
> https://lore.kernel.org/all/20241030052933.1041408-1-yun.z...@windriver.com/
> ---
> include/linux/pid_namespace.h | 1 +
> kernel/pid.c | 12 +++++------
> kernel/pid_namespace.c | 34 ++++++++++++++++++++++++++-----
> kernel/sysctl.c | 9 --------
> kernel/trace/pid_list.c | 2 +-
> kernel/trace/trace.h | 2 --
> kernel/trace/trace_sched_switch.c | 2 +-
> 7 files changed, 38 insertions(+), 24 deletions(-)
...
> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> index d70ab49d5b4a..a5a8254825d5 100644
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -111,6 +111,7 @@ static struct pid_namespace *create_pid_namespace(struct
> user_namespace *user_ns
> ns->user_ns = get_user_ns(user_ns);
> ns->ucounts = ucounts;
> ns->pid_allocated = PIDNS_ADDING;
> + ns->pid_max = parent_pid_ns->pid_max;
> #if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
> ns->memfd_noexec_scope = pidns_memfd_noexec_scope(parent_pid_ns);
> #endif
> @@ -280,19 +281,44 @@ static int pid_ns_ctl_handler(const struct ctl_table
> *table, int write,
>
> return ret;
> }
> +#endif /* CONFIG_CHECKPOINT_RESTORE */
> +
> +static int pid_max_ns_ctl_handler(const struct ctl_table *table, int write,
> + void *buffer, size_t *lenp, loff_t *ppos)
> +{
> + struct pid_namespace *pid_ns = task_active_pid_ns(current);
> + struct ctl_table tmp = *table;
> +
> + if (write && !checkpoint_restore_ns_capable(pid_ns->user_ns))
> + return -EPERM;
> +
> + tmp.data = &pid_ns->pid_max;
> + if (pid_ns->parent)
> + tmp.extra2 = &pid_ns->parent->pid_max;
> +
> + return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
> +}
>
> -extern int pid_max;
> static struct ctl_table pid_ns_ctl_table[] = {
> +#ifdef CONFIG_CHECKPOINT_RESTORE
> {
> .procname = "ns_last_pid",
> .maxlen = sizeof(int),
> .mode = 0666, /* permissions are checked in the handler */
> .proc_handler = pid_ns_ctl_handler,
> .extra1 = SYSCTL_ZERO,
> - .extra2 = &pid_max,
> + .extra2 = &init_pid_ns.pid_max,
> },
> -};
> #endif /* CONFIG_CHECKPOINT_RESTORE */
> + {
> + .procname = "pid_max",
> + .maxlen = sizeof(int),
> + .mode = 0644,
> + .proc_handler = pid_max_ns_ctl_handler,
> + .extra1 = &pid_max_min,
> + .extra2 = &pid_max_max,
> + },
> +};
I see here that the sysctls are without sentinel.
Reviewed-by: Joel Granados <joel.grana...@kernel.org>
--
Joel Granados
