Messages in this thread | | | Date | Sun, 7 Oct 2012 14:20:34 +0400 | From | Andrew Vagin <> | Subject | Re: [PATCH] [RFC] pidns: don't zap processes several times |
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The test program is attached.
On Sun, Oct 07, 2012 at 01:49:18PM +0400, Andrew Vagin wrote: > I wrote a test program. It does clone(CLONE_NEWPID | CLONE_VM) and > sleep(), a new task repeates the same actions. This program creates > 4000 tasks. When I tried to kill all this processes, a system was > inaccessible for some minutes. > > The system is inaccessible, because each process calls > zap_pid_ns_processes, which tries to kill subprocesses under > tasklist_lock. The most time are required for find_vpid(). > > I suggest to mark sub-namespaces in zap_pid_ns_processes. > zap_pid_ns_processes for marked pidns doesn't kill tasks, > it only waits them. > > I am not sure, that this idea is correct, but it helps. > > Maybe we should restrict depth of pidns? > Why can't we enumerate task->children instead of using find_vpid()? > > Cc: Oleg Nesterov <oleg@redhat.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Serge Hallyn <serge.hallyn@canonical.com> > Cc: Paul Gortmaker <paul.gortmaker@windriver.com> > Cc: "Eric W. Biederman" <ebiederm@xmission.com> > Cc: Vasiliy Kulikov <segoon@openwall.com> > Cc: Cyrill Gorcunov <gorcunov@openvz.org> > Cc: Pavel Emelyanov <xemul@parallels.com> > Signed-off-by: Andrew Vagin <avagin@openvz.org> > --- > include/linux/pid_namespace.h | 1 + > kernel/pid_namespace.c | 14 ++++++++++++-- > 2 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h > index 00474b0..28073a0 100644 > --- a/include/linux/pid_namespace.h > +++ b/include/linux/pid_namespace.h > @@ -34,6 +34,7 @@ struct pid_namespace { > kgid_t pid_gid; > int hide_pid; > int reboot; /* group exit code if this pidns was rebooted */ > + atomic_t zapped; /* non zero if all process were killed */ > }; > > extern struct pid_namespace init_pid_ns; > diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c > index b051fa6..7db7dcd 100644 > --- a/kernel/pid_namespace.c > +++ b/kernel/pid_namespace.c > @@ -177,21 +177,31 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) > * maintain a tasklist for each pid namespace. > * > */ > + > + if (atomic_read(&pid_ns->zapped)) > + goto wait; /* All processes were already killed */ > + > read_lock(&tasklist_lock); > nr = next_pidmap(pid_ns, 1); > while (nr > 0) { > rcu_read_lock(); > > task = pid_task(find_vpid(nr), PIDTYPE_PID); > - if (task && !__fatal_signal_pending(task)) > + if (task && !__fatal_signal_pending(task)) { > + struct pid_namespace *ns; > + > send_sig_info(SIGKILL, SEND_SIG_FORCED, task); > + ns = task_active_pid_ns(task); > + if (unlikely(ns->child_reaper == task)) > + atomic_set(&ns->zapped, 1); > + } > > rcu_read_unlock(); > > nr = next_pidmap(pid_ns, nr); > } > read_unlock(&tasklist_lock); > - > +wait: > /* Firstly reap the EXIT_ZOMBIE children we may have. */ > do { > clear_thread_flag(TIF_SIGPENDING); > -- > 1.7.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ #define _GNU_SOURCE #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> #include <sched.h>
struct args { char body[1024]; char ptr[0]; };
static i = 0;
static int ns_exec(void *_arg) { pid_t pid; int status; struct args *args = malloc(sizeof(struct args));
if (args == NULL) { printf("Can't allocate memory\n"); return 1; }
if (i++ > 4000) return 0;
pid = clone(ns_exec, args->ptr, CLONE_NEWPID | CLONE_VM | SIGCHLD, NULL); if (pid == -1) { printf("clone() failed: %m\n"); return 1; }
while (1) sleep(1000);
return 0; }
int main(int argc, char **argv) { ns_exec(NULL); return 0; }
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