The patch titled
pgrp: will_become_orphaned_pgrp: partially fix insufficient ->exit_state check
has been added to the -mm tree. Its filename is
will_become_orphaned_pgrp-partially-fix-insufficient-exit_state-check.patch
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: pgrp: will_become_orphaned_pgrp: partially fix insufficient ->exit_state check
From: Oleg Nesterov <oleg@xxxxxxxxxx>
p->exit_state != 0 doesn't mean this process is dead, it may have sub-threads.
Change the code to use "p->exit_state && thread_group_empty(p)" instead.
Without this patch, ^Z doesn't deliver SIGTSTP to the foreground process if
the main thread has exited.
However, the new check is not perfect too. There is a window when
exit_notify() drops tasklist and before release_task(). Suppose that the last
(non-leader) thread exits. This means that entire group exits, but
thread_group_empty() is not true yet.
As Eric pointed out, is_global_init() is wrong as well, but I did not dare to
do other changes.
Just for the record, has_stopped_jobs() is absolutely wrong too. But we can't
fix it now, we should first fix SIGNAL_STOP_STOPPED issues.
And. Even with this patch ^Z doesn't play well with the dead main thread.
The task is stopped correctly but do_wait(WSTOPPED) can't see it. This is
another unrelated issue, will be (hopefully) fixed separately.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff -puN kernel/exit.c~will_become_orphaned_pgrp-partially-fix-insufficient-exit_state-check kernel/exit.c
--- a/kernel/exit.c~will_become_orphaned_pgrp-partially-fix-insufficient-exit_state-check
+++ a/kernel/exit.c
@@ -214,20 +214,19 @@ struct pid *session_of_pgrp(struct pid *
static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
{
struct task_struct *p;
- int ret = 1;
do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
- if (p == ignored_task
- || p->exit_state
- || is_global_init(p->real_parent))
+ if ((p == ignored_task) ||
+ (p->exit_state && thread_group_empty(p)) ||
+ is_global_init(p->real_parent))
continue;
+
if (task_pgrp(p->real_parent) != pgrp &&
- task_session(p->real_parent) == task_session(p)) {
- ret = 0;
- break;
- }
+ task_session(p->real_parent) == task_session(p))
+ return 0;
} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
- return ret; /* (sighing) "Often!" */
+
+ return 1;
}
int is_current_pgrp_orphaned(void)
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
git-hrt.patch
kthread-call-wake_up_process-without-the-lock-being-held.patch
documentation-atomic_add_unless-doesnt-imply-mb-on-failure-fix.patch
mmap_region-cleanup-the-final-vma_merge-related-code.patch
remove-unused-variable-from-send_signal.patch
turn-legacy_queue-macro-into-static-inline-function.patch
consolidate-checking-for-ignored-legacy-signals.patch
consolidate-checking-for-ignored-legacy-signals-simplify.patch
signals-do_signal_stop-use-signal_group_exit.patch
signals-do_group_exit-use-signal_group_exit-more-consistently.patch
lock_task_sighand-add-rcu-lock-unlock.patch
k_getrusage-dont-take-rcu_read_lock.patch
do_task_stat-dont-take-rcu_read_lock.patch
signals-consolidate-checks-for-whether-or-not-to-ignore-a-signal.patch
signals-clean-dequeue_signal-from-excess-checks-and-assignments.patch
signals-consolidate-send_sigqueue-and-send_group_sigqueue.patch
signals-cleanup-security_task_kill-usage-implementation.patch
introduce-kill_orphaned_pgrp-helper.patch
will_become_orphaned_pgrp-partially-fix-insufficient-exit_state-check.patch
exit_notify-fix-kill_orphaned_pgrp-usage-with-mt-exit.patch
workqueues-shrink-cpu_populated_map-when-cpu-dies.patch
workqueues-shrink-cpu_populated_map-when-cpu-dies-fix.patch
cleanup_workqueue_thread-remove-the-unneeded-cpu-parameter.patch
simplify-cpu_hotplug_begin-put_online_cpus.patch
redo-locking-of-tty-pgrp.patch
resume-tty-on-susp-and-fix-crnl-order-in-n_tty-line-discipline.patch
procfs-task-exe-symlink.patch
procfs-task-exe-symlink-fix.patch
procfs-task-exe-symlink-fix-2.patch
free_pidmap-turn-it-into-free_pidmapstruct-upid.patch
put_pid-make-sure-we-dont-free-the-live-pid.patch
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