[kernel] r15922 - in dists/lenny/linux-2.6/debian: . patches/bugfix/all patches/features/all/openvz patches/series
Ben Hutchings
benh at alioth.debian.org
Fri Jul 2 01:13:00 UTC 2010
Author: benh
Date: Fri Jul 2 01:12:56 2010
New Revision: 15922
Log:
pid_ns: Ensure that child_reaper is always valid (Closes: #570350)
Added:
dists/lenny/linux-2.6/debian/patches/bugfix/all/pid_ns-change-child_reaper-when-init-group_leader-exits.patch
dists/lenny/linux-2.6/debian/patches/bugfix/all/pid_ns-zap_pid_ns_processes-fix-the-child_reaper.patch
dists/lenny/linux-2.6/debian/patches/series/25
Modified:
dists/lenny/linux-2.6/debian/changelog
dists/lenny/linux-2.6/debian/patches/features/all/openvz/0073-pidns-zap-ve-process-only-when-killing-ve-s-init-pi.patch
dists/lenny/linux-2.6/debian/patches/features/all/openvz/openvz.patch
Modified: dists/lenny/linux-2.6/debian/changelog
==============================================================================
--- dists/lenny/linux-2.6/debian/changelog Thu Jul 1 11:32:59 2010 (r15921)
+++ dists/lenny/linux-2.6/debian/changelog Fri Jul 2 01:12:56 2010 (r15922)
@@ -1,3 +1,10 @@
+linux-2.6 (2.6.26-25) UNRELEASED; urgency=low
+
+ [ Ben Hutchings ]
+ * pid_ns: Ensure that child_reaper is always valid (Closes: #570350)
+
+ -- Ben Hutchings <ben at decadent.org.uk> Fri, 02 Jul 2010 01:36:02 +0100
+
linux-2.6 (2.6.26-24) stable; urgency=high
[ Ben Hutchings ]
Added: dists/lenny/linux-2.6/debian/patches/bugfix/all/pid_ns-change-child_reaper-when-init-group_leader-exits.patch
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ dists/lenny/linux-2.6/debian/patches/bugfix/all/pid_ns-change-child_reaper-when-init-group_leader-exits.patch Fri Jul 2 01:12:56 2010 (r15922)
@@ -0,0 +1,165 @@
+From: Oleg Nesterov <oleg at tv-sign.ru>
+Date: Tue, 2 Sep 2008 14:35:49 -0700
+Subject: [PATCH 2/2] pid_ns: (BUG 11391) change ->child_reaper when init->group_leader exits
+
+commit 950bbabb5a804690a0201190de5c22837f72f83f upstream.
+
+We don't change pid_ns->child_reaper when the main thread of the
+subnamespace init exits. As Robert Rex <robert.rex at exasol.com> pointed
+out this is wrong.
+
+Yes, the re-parenting itself works correctly, but if the reparented task
+exits it needs ->parent->nsproxy->pid_ns in do_notify_parent(), and if the
+main thread is zombie its ->nsproxy was already cleared by
+exit_task_namespaces().
+
+Introduce the new function, find_new_reaper(), which finds the new
+->parent for the re-parenting and changes ->child_reaper if needed. Kill
+the now unneeded exit_child_reaper().
+
+Also move the changing of ->child_reaper from zap_pid_ns_processes() to
+find_new_reaper(), this consolidates the games with ->child_reaper and
+makes it stable under tasklist_lock.
+
+Addresses http://bugzilla.kernel.org/show_bug.cgi?id=11391
+
+Reported-by: Robert Rex <robert.rex at exasol.com>
+Signed-off-by: Oleg Nesterov <oleg at tv-sign.ru>
+Acked-by: Serge Hallyn <serue at us.ibm.com>
+Acked-by: Pavel Emelyanov <xemul at openvz.org>
+Acked-by: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
+Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
+[bwh: Adjust context for 2.6.26]
+---
+ kernel/exit.c | 78 +++++++++++++++++++++---------------------------
+ kernel/pid_namespace.c | 6 ----
+ 2 files changed, 34 insertions(+), 50 deletions(-)
+
+diff --git a/kernel/exit.c b/kernel/exit.c
+index 75c6473..25ed2ad 100644
+--- a/kernel/exit.c
++++ b/kernel/exit.c
+@@ -758,23 +758,48 @@ static void reparent_thread(struct task_struct *p, struct task_struct *father)
+ * the child reaper process (ie "init") in our pid
+ * space.
+ */
++static struct task_struct *find_new_reaper(struct task_struct *father)
++{
++ struct pid_namespace *pid_ns = task_active_pid_ns(father);
++ struct task_struct *thread;
++
++ thread = father;
++ while_each_thread(father, thread) {
++ if (thread->flags & PF_EXITING)
++ continue;
++ if (unlikely(pid_ns->child_reaper == father))
++ pid_ns->child_reaper = thread;
++ return thread;
++ }
++
++ if (unlikely(pid_ns->child_reaper == father)) {
++ write_unlock_irq(&tasklist_lock);
++ if (unlikely(pid_ns == &init_pid_ns))
++ panic("Attempted to kill init!");
++
++ zap_pid_ns_processes(pid_ns);
++ write_lock_irq(&tasklist_lock);
++ /*
++ * We can not clear ->child_reaper or leave it alone.
++ * There may by stealth EXIT_DEAD tasks on ->children,
++ * forget_original_parent() must move them somewhere.
++ */
++ pid_ns->child_reaper = init_pid_ns.child_reaper;
++ }
++
++ return pid_ns->child_reaper;
++}
++
+ static void forget_original_parent(struct task_struct *father)
+ {
+- struct task_struct *p, *n, *reaper = father;
++ struct task_struct *p, *n, *reaper;
+ struct list_head ptrace_dead;
+
+ INIT_LIST_HEAD(&ptrace_dead);
+
+ write_lock_irq(&tasklist_lock);
++ reaper = find_new_reaper(father);
+
+- do {
+- reaper = next_thread(reaper);
+- if (reaper == father) {
+- reaper = task_child_reaper(father);
+- break;
+- }
+- } while (reaper->flags & PF_EXITING);
+-
+ /*
+ * There are only two places where our children can be:
+ *
+@@ -929,39 +954,6 @@ static void check_stack_usage(void)
+ static inline void check_stack_usage(void) {}
+ #endif
+
+-static inline void exit_child_reaper(struct task_struct *tsk)
+-{
+- if (likely(tsk->group_leader != task_child_reaper(tsk)))
+- return;
+-
+- if (tsk->nsproxy->pid_ns == &init_pid_ns)
+- panic("Attempted to kill init!");
+-
+- /*
+- * @tsk is the last thread in the 'cgroup-init' and is exiting.
+- * Terminate all remaining processes in the namespace and reap them
+- * before exiting @tsk.
+- *
+- * Note that @tsk (last thread of cgroup-init) may not necessarily
+- * be the child-reaper (i.e main thread of cgroup-init) of the
+- * namespace i.e the child_reaper may have already exited.
+- *
+- * Even after a child_reaper exits, we let it inherit orphaned children,
+- * because, pid_ns->child_reaper remains valid as long as there is
+- * at least one living sub-thread in the cgroup init.
+-
+- * This living sub-thread of the cgroup-init will be notified when
+- * a child inherited by the 'child-reaper' exits (do_notify_parent()
+- * uses __group_send_sig_info()). Further, when reaping child processes,
+- * do_wait() iterates over children of all living sub threads.
+-
+- * i.e even though 'child_reaper' thread is listed as the parent of the
+- * orphaned children, any living sub-thread in the cgroup-init can
+- * perform the role of the child_reaper.
+- */
+- zap_pid_ns_processes(tsk->nsproxy->pid_ns);
+-}
+-
+ NORET_TYPE void do_exit(long code)
+ {
+ struct task_struct *tsk = current;
+@@ -1024,7 +1016,6 @@ NORET_TYPE void do_exit(long code)
+ }
+ group_dead = atomic_dec_and_test(&tsk->signal->live);
+ if (group_dead) {
+- exit_child_reaper(tsk);
+ hrtimer_cancel(&tsk->signal->real_timer);
+ exit_itimers(tsk->signal);
+ }
+diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
+index 598f1ee..fab8ea8 100644
+--- a/kernel/pid_namespace.c
++++ b/kernel/pid_namespace.c
+@@ -182,12 +182,6 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
+ rc = sys_wait4(-1, NULL, __WALL, NULL);
+ } while (rc != -ECHILD);
+
+- /*
+- * We can not clear ->child_reaper or leave it alone.
+- * There may by stealth EXIT_DEAD tasks on ->children,
+- * forget_original_parent() must move them somewhere.
+- */
+- pid_ns->child_reaper = init_pid_ns.child_reaper;
+ return;
+ }
+
Added: dists/lenny/linux-2.6/debian/patches/bugfix/all/pid_ns-zap_pid_ns_processes-fix-the-child_reaper.patch
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ dists/lenny/linux-2.6/debian/patches/bugfix/all/pid_ns-zap_pid_ns_processes-fix-the-child_reaper.patch Fri Jul 2 01:12:56 2010 (r15922)
@@ -0,0 +1,57 @@
+From: Oleg Nesterov <oleg at tv-sign.ru>
+Date: Tue, 2 Sep 2008 14:35:48 -0700
+Subject: [PATCH 1/2] pid_ns: zap_pid_ns_processes: fix the ->child_reaper changing
+
+commit add0d4dfd660e9e4fd0af3eac3cad23583c9558f upstream.
+
+zap_pid_ns_processes() sets pid_ns->child_reaper = NULL, this is wrong.
+
+Yes, we have already killed all tasks in this namespace, and sys_wait4()
+doesn't see any child. But this doesn't mean ->children list is empty, we
+may have EXIT_DEAD tasks which are not visible to do_wait(). In that case
+the subsequent forget_original_parent() will crash the kernel because it
+will try to re-parent these tasks to the NULL reaper.
+
+Even if there are no childs, it is not good that forget_original_parent()
+uses reaper == NULL.
+
+Change the code to set ->child_reaper = init_pid_ns.child_reaper instead.
+We could use pid_ns->parent->child_reaper as well, I think this does not
+really matter. These EXIT_DEAD tasks are not visible to the new ->parent
+after re-parenting, they will silently do release_task() eventually.
+
+Note that we must change ->child_reaper, otherwise
+forget_original_parent() will use reaper == father, and in that case we
+will hit the (correct) BUG_ON(!list_empty(&father->children)).
+
+Signed-off-by: Oleg Nesterov <oleg at tv-sign.ru>
+Acked-by: Serge Hallyn <serue at us.ibm.com>
+Acked-by: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
+Acked-by: Pavel Emelyanov <xemul at openvz.org>
+Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
+[bwh: Adjust context for 2.6.26]
+---
+ kernel/pid_namespace.c | 9 ++++++---
+ 1 files changed, 6 insertions(+), 3 deletions(-)
+
+diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
+index ea567b7..598f1ee 100644
+--- a/kernel/pid_namespace.c
++++ b/kernel/pid_namespace.c
+@@ -182,9 +182,12 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
+ rc = sys_wait4(-1, NULL, __WALL, NULL);
+ } while (rc != -ECHILD);
+
+-
+- /* Child reaper for the pid namespace is going away */
+- pid_ns->child_reaper = NULL;
++ /*
++ * We can not clear ->child_reaper or leave it alone.
++ * There may by stealth EXIT_DEAD tasks on ->children,
++ * forget_original_parent() must move them somewhere.
++ */
++ pid_ns->child_reaper = init_pid_ns.child_reaper;
+ return;
+ }
+
Modified: dists/lenny/linux-2.6/debian/patches/features/all/openvz/0073-pidns-zap-ve-process-only-when-killing-ve-s-init-pi.patch
==============================================================================
--- dists/lenny/linux-2.6/debian/patches/features/all/openvz/0073-pidns-zap-ve-process-only-when-killing-ve-s-init-pi.patch Thu Jul 1 11:32:59 2010 (r15921)
+++ dists/lenny/linux-2.6/debian/patches/features/all/openvz/0073-pidns-zap-ve-process-only-when-killing-ve-s-init-pi.patch Fri Jul 2 01:12:56 2010 (r15922)
@@ -1,13 +1,15 @@
-From d876c93aa8cbd06f47e3669f5d8fcec1afc77ed4 Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov <khlebnikov at openvz.org>
Date: Tue, 10 Mar 2009 14:31:18 +0300
Subject: [PATCH] pidns: zap ve process only when killing ve's init pid-ns
+commit d876c93aa8cbd06f47e3669f5d8fcec1afc77ed4 upstream.
+
This prevents task genocide when zapping nested pid-ns in same ve,
and affects ve0 only.
Signed-off-by: Konstantin Khlebnikov <khlebnikov at openvz.org>
Signed-off-by: Pavel Emelyanov <xemul at openvz.org>
+[bwh: Adjust context]
---
kernel/pid_namespace.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
@@ -24,8 +26,5 @@
+ if (get_exec_env()->ve_ns->pid_ns == pid_ns)
+ zap_ve_processes(get_exec_env());
#endif
- /* Child reaper for the pid namespace is going away */
- pid_ns->child_reaper = NULL;
---
-1.6.2
-
+ return;
+ }
Modified: dists/lenny/linux-2.6/debian/patches/features/all/openvz/openvz.patch
==============================================================================
--- dists/lenny/linux-2.6/debian/patches/features/all/openvz/openvz.patch Thu Jul 1 11:32:59 2010 (r15921)
+++ dists/lenny/linux-2.6/debian/patches/features/all/openvz/openvz.patch Fri Jul 2 01:12:56 2010 (r15922)
@@ -58959,6 +58959,23 @@
static void
reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
+@@ -764,7 +784,7 @@ static struct task_struct *find_new_reaper(struct task_struct *father)
+ struct task_struct *thread;
+
+ thread = father;
+- while_each_thread(father, thread) {
++ while_each_thread_ve(father, thread) {
+ if (thread->flags & PF_EXITING)
+ continue;
+ if (unlikely(pid_ns->child_reaper == father))
+@@ -778,6 +798,7 @@ static struct task_struct *find_new_reaper(struct task_struct *father)
+ panic("Attempted to kill init!");
+
+ zap_pid_ns_processes(pid_ns);
++ (void)virtinfo_gencall(VIRTINFO_DOEXIT, NULL);
+ write_lock_irq(&tasklist_lock);
+ /*
+ * We can not clear ->child_reaper or leave it alone.
@@ -864,6 +884,10 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
!capable(CAP_KILL))
tsk->exit_signal = SIGCHLD;
@@ -58978,14 +58995,6 @@
/* mt-exec, de_thread() is waiting for us */
if (thread_group_leader(tsk) &&
-@@ -953,6 +978,7 @@ static inline void exit_child_reaper(struct task_struct *tsk)
- * perform the role of the child_reaper.
- */
- zap_pid_ns_processes(tsk->nsproxy->pid_ns);
-+ (void)virtinfo_gencall(VIRTINFO_DOEXIT, NULL);
- }
-
- NORET_TYPE void do_exit(long code)
@@ -1023,12 +1049,14 @@ NORET_TYPE void do_exit(long code)
}
acct_collect(code, group_dead);
@@ -60678,15 +60687,15 @@
{
int nr;
@@ -183,6 +340,9 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
+ rc = sys_wait4(-1, NULL, __WALL, NULL);
} while (rc != -ECHILD);
-
+#ifdef CONFIG_VE
+ zap_ve_processes(get_exec_env());
+#endif
- /* Child reaper for the pid namespace is going away */
- pid_ns->child_reaper = NULL;
return;
+ }
+
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index dbd8398..f331727 100644
--- a/kernel/posix-timers.c
Added: dists/lenny/linux-2.6/debian/patches/series/25
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ dists/lenny/linux-2.6/debian/patches/series/25 Fri Jul 2 01:12:56 2010 (r15922)
@@ -0,0 +1,2 @@
++ bugfix/all/pid_ns-zap_pid_ns_processes-fix-the-child_reaper.patch
++ bugfix/all/pid_ns-change-child_reaper-when-init-group_leader-exits.patch
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