The patch titled Subject: sysctl: add the kernel.ns_last_pid control has been removed from the -mm tree. Its filename was sysctl-add-the-kernelns_last_pid-control.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ From: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Subject: sysctl: add the kernel.ns_last_pid control The sysctl works on the current task's pid namespace, getting and setting its last_pid field. Writing is allowed for CAP_SYS_ADMIN-capable tasks thus making it possible to create a task with desired pid value. This ability is required badly for the checkpoint/restore in userspace. This approach suits all the parties for now. Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Serge Hallyn <serue@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/sysctl/kernel.txt | 8 +++++++ kernel/pid.c | 4 ++- kernel/pid_namespace.c | 31 ++++++++++++++++++++++++++++++ 3 files changed, 42 insertions(+), 1 deletion(-) diff -puN Documentation/sysctl/kernel.txt~sysctl-add-the-kernelns_last_pid-control Documentation/sysctl/kernel.txt --- a/Documentation/sysctl/kernel.txt~sysctl-add-the-kernelns_last_pid-control +++ a/Documentation/sysctl/kernel.txt @@ -415,6 +415,14 @@ PIDs of value pid_max or larger are not ============================================================== +ns_last_pid: + +The last pid allocated in the current (the one task using this sysctl +lives in) pid namespace. When selecting a pid for a next task on fork +kernel tries to allocate a number starting from this one. + +============================================================== + powersave-nap: (PPC only) If set, Linux-PPC will use the 'nap' mode of powersaving, diff -puN kernel/pid.c~sysctl-add-the-kernelns_last_pid-control kernel/pid.c --- a/kernel/pid.c~sysctl-add-the-kernelns_last_pid-control +++ a/kernel/pid.c @@ -137,7 +137,9 @@ static int pid_before(int base, int a, i } /* - * We might be racing with someone else trying to set pid_ns->last_pid. + * We might be racing with someone else trying to set pid_ns->last_pid + * at the pid allocation time (there's also a sysctl for this, but racing + * with this one is OK, see comment in kernel/pid_namespace.c about it). * We want the winner to have the "later" value, because if the * "earlier" value prevails, then a pid may get reused immediately. * diff -puN kernel/pid_namespace.c~sysctl-add-the-kernelns_last_pid-control kernel/pid_namespace.c --- a/kernel/pid_namespace.c~sysctl-add-the-kernelns_last_pid-control +++ a/kernel/pid_namespace.c @@ -191,9 +191,40 @@ void zap_pid_ns_processes(struct pid_nam return; } +static int pid_ns_ctl_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + struct ctl_table tmp = *table; + + if (write && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + /* + * Writing directly to ns' last_pid field is OK, since this field + * is volatile in a living namespace anyway and a code writing to + * it should synchronize its usage with external means. + */ + + tmp.data = ¤t->nsproxy->pid_ns->last_pid; + return proc_dointvec(&tmp, write, buffer, lenp, ppos); +} + +static struct ctl_table pid_ns_ctl_table[] = { + { + .procname = "ns_last_pid", + .maxlen = sizeof(int), + .mode = 0666, /* permissions are checked in the handler */ + .proc_handler = pid_ns_ctl_handler, + }, + { } +}; + +static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } }; + static __init int pid_namespaces_init(void) { pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); + register_sysctl_paths(kern_path, pid_ns_ctl_table); return 0; } _ Patches currently in -mm which might be from xemul@xxxxxxxxxxxxx are origin.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html