From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Aaron Tomlin <atomlin@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Sterling Alexander <stalexan@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH -mm 2/3] exit: reparent: call forget_original_parent() under tasklist_lock
Date: Thu, 20 Nov 2014 19:34:26 +0100 [thread overview]
Message-ID: <20141120183426.GA10273@redhat.com> (raw)
In-Reply-To: <20141120183400.GA9622@redhat.com>
Shift "release dead children" loop from forget_original_parent() to
its caller, exit_notify(). It is safe to reap them even if our parent
reaps us right after we drop tasklist_lock, those children no longer
have any connection to the exiting task.
And this allows us to avoid write_lock_irq(tasklist_lock) right after
it was released by forget_original_parent(), we can simply call it
with tasklist_lock held.
While at it, move the comment about forget_original_parent() up to
this function.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/exit.c | 47 +++++++++++++++++++++++------------------------
1 files changed, 23 insertions(+), 24 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index 81b62f8..ccf27cb 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -560,19 +560,26 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p,
kill_orphaned_pgrp(p, father);
}
-static void forget_original_parent(struct task_struct *father)
+/*
+ * This does two things:
+ *
+ * A. Make init inherit all the child processes
+ * B. Check to see if any process groups have become orphaned
+ * as a result of our exiting, and if they have any stopped
+ * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
+ */
+static void forget_original_parent(struct task_struct *father,
+ struct list_head *dead)
{
- struct task_struct *p, *t, *n, *reaper;
- LIST_HEAD(dead_children);
+ struct task_struct *p, *t, *reaper;
- write_lock_irq(&tasklist_lock);
if (unlikely(!list_empty(&father->ptraced)))
- exit_ptrace(father, &dead_children);
+ exit_ptrace(father, dead);
/* Can drop and reacquire tasklist_lock */
reaper = find_child_reaper(father);
if (list_empty(&father->children))
- goto unlock;
+ return;
reaper = find_new_reaper(father, reaper);
list_for_each_entry(p, &father->children, sibling) {
@@ -590,16 +597,9 @@ static void forget_original_parent(struct task_struct *father)
* notify anyone anything has happened.
*/
if (!same_thread_group(reaper, father))
- reparent_leader(father, p, &dead_children);
+ reparent_leader(father, p, dead);
}
list_splice_tail_init(&father->children, &reaper->children);
- unlock:
- write_unlock_irq(&tasklist_lock);
-
- list_for_each_entry_safe(p, n, &dead_children, ptrace_entry) {
- list_del_init(&p->ptrace_entry);
- release_task(p);
- }
}
/*
@@ -609,18 +609,12 @@ static void forget_original_parent(struct task_struct *father)
static void exit_notify(struct task_struct *tsk, int group_dead)
{
bool autoreap;
-
- /*
- * This does two things:
- *
- * A. Make init inherit all the child processes
- * B. Check to see if any process groups have become orphaned
- * as a result of our exiting, and if they have any stopped
- * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
- */
- forget_original_parent(tsk);
+ struct task_struct *p, *n;
+ LIST_HEAD(dead);
write_lock_irq(&tasklist_lock);
+ forget_original_parent(tsk, &dead);
+
if (group_dead)
kill_orphaned_pgrp(tsk->group_leader, NULL);
@@ -644,6 +638,11 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
wake_up_process(tsk->signal->group_exit_task);
write_unlock_irq(&tasklist_lock);
+ list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
+ list_del_init(&p->ptrace_entry);
+ release_task(p);
+ }
+
/* If the process is dead, release it - nobody will wait for it */
if (autoreap)
release_task(tsk);
--
1.5.5.1
next prev parent reply other threads:[~2014-11-20 18:34 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-07 20:14 [PATCH 0/4] proc: deuglify task_state() Oleg Nesterov
2014-11-07 20:14 ` [PATCH 1/4] proc: task_state: read cred->group_info outside of task_lock() Oleg Nesterov
2014-11-07 20:14 ` [PATCH 2/4] proc: task_state: deuglify the max_fds calculation Oleg Nesterov
2014-11-07 20:14 ` [PATCH 3/4] proc: task_state: move the main seq_printf() outside of rcu_read_lock() Oleg Nesterov
2014-11-13 18:04 ` Paul E. McKenney
2014-11-07 20:14 ` [PATCH 4/4] proc: task_state: ptrace_parent() doesn't need pid_alive() check Oleg Nesterov
2014-11-10 21:59 ` [PATCH 0/5] exit: reparent zombie fix + cleanups/optimizations Oleg Nesterov
2014-11-10 22:00 ` [PATCH 1/5] sched_show_task: fix unsafe usage of ->real_parent Oleg Nesterov
2014-11-11 10:39 ` Peter Zijlstra
2014-11-10 22:00 ` [PATCH 2/5] exit: reparent: use ->ptrace_entry rather than ->sibling for EXIT_DEAD tasks Oleg Nesterov
2014-11-10 22:00 ` [PATCH 3/5] exit: reparent: cleanup the changing of ->parent Oleg Nesterov
2014-11-10 22:00 ` [PATCH 4/5] exit: reparent: cleanup the usage of reparent_leader() Oleg Nesterov
2014-11-10 22:00 ` [PATCH 5/5] exit: ptrace: shift "reap dead" code from exit_ptrace() to forget_original_parent() Oleg Nesterov
2014-11-14 1:37 ` [PATCH 0/5] exit: more cleanups/optimizations Oleg Nesterov
2014-11-14 1:38 ` [PATCH 1/5] exit: wait: cleanup the ptrace_reparented() checks Oleg Nesterov
2014-11-14 1:38 ` [PATCH 2/5] exit: wait: don't use zombie->real_parent Oleg Nesterov
2014-11-14 1:38 ` [PATCH 3/5] exit: wait: drop tasklist_lock before psig->c* accounting Oleg Nesterov
2014-11-14 1:38 ` [PATCH 4/5] exit: release_task: fix the comment about group leader accounting Oleg Nesterov
2014-11-14 1:38 ` [PATCH 5/5] exit: proc: don't try to flush /proc/tgid/task/tgid Oleg Nesterov
2014-11-18 21:29 ` [PATCH 0/6] exit: find_new_reaper() fixes/cleanups Oleg Nesterov
2014-11-18 21:30 ` [PATCH 1/6] exit: reparent: fix the dead-parent PR_SET_CHILD_SUBREAPER reparenting Oleg Nesterov
2014-11-18 21:30 ` [PATCH 2/6] exit: reparent: fix the cross-namespace " Oleg Nesterov
2014-11-18 21:30 ` [PATCH 3/6] exit: reparent: s/while_each_thread/for_each_thread/ in find_new_reaper() Oleg Nesterov
2014-11-18 21:30 ` [PATCH 4/6] exit: reparent: document the ->has_child_subreaper checks Oleg Nesterov
2014-11-18 21:30 ` [PATCH 5/6] exit: reparent: introduce find_child_reaper() Oleg Nesterov
2014-11-18 21:30 ` [PATCH 6/6] exit: reparent: introduce find_alive_thread() Oleg Nesterov
2014-11-20 18:34 ` [PATCH 0/3] exit: avoid O(n ** 2) thread-list scan on group-exit if possible Oleg Nesterov
2014-11-20 18:34 ` [PATCH -mm 1/3] exit: reparent: avoid find_new_reaper() if no children Oleg Nesterov
2014-11-20 22:37 ` Andrew Morton
2014-11-21 20:01 ` Oleg Nesterov
2014-11-20 18:34 ` Oleg Nesterov [this message]
2014-11-20 18:34 ` [PATCH -mm 3/3] exit: exit_notify: re-use "dead" list to autoreap current Oleg Nesterov
2014-11-24 20:06 ` [PATCH 0/2] exit/pid_ns: comments + simple fix Oleg Nesterov
2014-11-24 20:06 ` [PATCH 1/2] exit: reparent: fix/update the comments in zap_pid_ns_processes() Oleg Nesterov
2014-11-24 20:14 ` Oleg Nesterov
2014-11-24 22:07 ` Eric W. Biederman
2014-11-25 16:57 ` Oleg Nesterov
2014-11-25 17:17 ` Oleg Nesterov
2014-11-24 20:06 ` [PATCH 2/2] exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting Oleg Nesterov
2014-11-24 21:46 ` Eric W. Biederman
2014-11-25 17:07 ` Oleg Nesterov
2014-11-25 17:50 ` Eric W. Biederman
2014-11-25 18:15 ` Oleg Nesterov
2014-11-25 18:43 ` Eric W. Biederman
2014-11-25 18:59 ` Oleg Nesterov
2014-11-24 21:27 ` [PATCH 0/2] exit/pid_ns: comments + simple fix Eric W. Biederman
2014-11-24 21:38 ` Oleg Nesterov
2014-11-24 21:48 ` Eric W. Biederman
2014-11-25 16:57 ` Oleg Nesterov
2014-11-26 23:54 ` [PATCH v2 " Oleg Nesterov
2014-11-26 23:54 ` [PATCH v2 1/2] exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting Oleg Nesterov
2014-11-27 15:44 ` Eric W. Biederman
2014-11-26 23:54 ` [PATCH v2 2/2] exit: pidns: fix/update the comments in zap_pid_ns_processes() Oleg Nesterov
2014-12-01 22:39 ` Andrew Morton
2014-12-01 23:24 ` Oleg Nesterov
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