The patch titled
make kernel threads invisible to /sbin/init
has been added to the -mm tree. Its filename is
make-kernel-threads-invisible-to-sbin-init.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: make kernel threads invisible to /sbin/init
From: Oleg Nesterov <oleg@xxxxxxxxxx>
1. rename reparent_to_init() to reparent_kthread() and export it
2. use init_pid_ns.child_reaper instead of child_reaper(current)
3. set ->exit_signal = -1, so init can't see us and we don't use
it to reap the task.
4. add reparent_kthread() to kthread() and stopmachine()
See also
http://marc.info/?t=117580282200003&r=1
http://marc.info/?t=95299284800003&r=1
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Robin Holt <holt@xxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sched.h | 1 +
kernel/exit.c | 16 ++++++++--------
kernel/kthread.c | 1 +
kernel/stop_machine.c | 1 +
4 files changed, 11 insertions(+), 8 deletions(-)
diff -puN include/linux/sched.h~make-kernel-threads-invisible-to-sbin-init include/linux/sched.h
--- a/include/linux/sched.h~make-kernel-threads-invisible-to-sbin-init
+++ a/include/linux/sched.h
@@ -1404,6 +1404,7 @@ extern void exit_itimers(struct signal_s
extern NORET_TYPE void do_group_exit(int);
+extern void reparent_kthread(void);
extern void daemonize(const char *, ...);
extern int allow_signal(int);
extern int disallow_signal(int);
diff -puN kernel/exit.c~make-kernel-threads-invisible-to-sbin-init kernel/exit.c
--- a/kernel/exit.c~make-kernel-threads-invisible-to-sbin-init
+++ a/kernel/exit.c
@@ -257,7 +257,7 @@ static int has_stopped_jobs(struct pid *
}
/**
- * reparent_to_init - Reparent the calling kernel thread to the init task of the pid space that the thread belongs to.
+ * reparent_kthread - Reparent the calling kernel thread to the init task of the pid space that the thread belongs to.
*
* If a kernel thread is launched as a result of a system call, or if
* it ever exits, it should generally reparent itself to init so that
@@ -266,20 +266,20 @@ static int has_stopped_jobs(struct pid *
* The various task state such as scheduling policy and priority may have
* been inherited from a user process, so we reset them to sane values here.
*
- * NOTE that reparent_to_init() gives the caller full capabilities.
+ * NOTE that reparent_kthread() gives the caller full capabilities.
*/
-static void reparent_to_init(void)
+void reparent_kthread(void)
{
write_lock_irq(&tasklist_lock);
ptrace_unlink(current);
remove_parent(current);
- current->parent = child_reaper(current);
- current->real_parent = child_reaper(current);
+ current->parent = init_pid_ns.child_reaper;
+ current->real_parent = current->parent;
add_parent(current);
- /* Set the exit signal to SIGCHLD so we signal init on exit */
- current->exit_signal = SIGCHLD;
+ /* make the task auto-reap */
+ current->exit_signal = -1;
security_task_reparent_to_init(current);
write_unlock_irq(&tasklist_lock);
@@ -393,7 +393,7 @@ void daemonize(const char *name, ...)
current->files = init_task.files;
atomic_inc(¤t->files->count);
- reparent_to_init();
+ reparent_kthread();
if (!has_rt_policy(current) && (task_nice(current) < 0))
set_user_nice(current, 0);
diff -puN kernel/kthread.c~make-kernel-threads-invisible-to-sbin-init kernel/kthread.c
--- a/kernel/kthread.c~make-kernel-threads-invisible-to-sbin-init
+++ a/kernel/kthread.c
@@ -82,6 +82,7 @@ static int kthread(void *_create)
sigset_t blocked;
int ret = -EINTR;
+ reparent_kthread();
kthread_exit_files();
/* Copy data: it's on keventd's stack */
diff -puN kernel/stop_machine.c~make-kernel-threads-invisible-to-sbin-init kernel/stop_machine.c
--- a/kernel/stop_machine.c~make-kernel-threads-invisible-to-sbin-init
+++ a/kernel/stop_machine.c
@@ -34,6 +34,7 @@ static int stopmachine(void *cpu)
int irqs_disabled = 0;
int prepared = 0;
+ reparent_kthread();
set_cpus_allowed(current, cpumask_of_cpu((int)(long)cpu));
/* Ack: we are alive */
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
git-dvb.patch
smaps-add-clear_refs-file-to-clear-reference-fix.patch
fix-refrigerator-vs-thaw_process-race.patch
doc-atomic_add_unless-doesnt-imply-mb-on-failure.patch
clone-flag-clone_parent_tidptr-leaves-invalid-results-in-memory.patch
allow-access-to-proc-pid-fd-after-setuid.patch
freezer-task-exit_state-should-be-treated-as-bolean.patch
softlockup-trivial-s-99-max_rt_prio.patch
fix-race-between-proc_get_inode-and-remove_proc_entry.patch
getrusage-fill-ru_inblock-and-ru_oublock-fields-if-possible.patch
futex-restartable-futex_wait.patch
futex-restartable-futex_wait-fix.patch
add-support-for-deferrable-timers-respun.patch
add-support-for-deferrable-timers-respun-tidy.patch
add-support-for-deferrable-timers-respun-fix.patch
add-a-new-deferrable-delayed-work-init.patch
reimplement-flush_workqueue.patch
implement-flush_work.patch
implement-flush_work-sanity.patch
implement-flush_work_keventd.patch
flush_workqueue-use-preempt_disable-to-hold-off-cpu-hotplug.patch
flush_cpu_workqueue-dont-flush-an-empty-worklist.patch
aio-use-flush_work.patch
kblockd-use-flush_work.patch
relayfs-use-flush_keventd_work.patch
tg3-use-flush_keventd_work.patch
e1000-use-flush_keventd_work.patch
libata-use-flush_work.patch
phy-use-flush_work.patch
call-cpu_chain-with-cpu_down_failed-if-cpu_down_prepare-failed.patch
slab-use-cpu_lock_.patch
workqueue-fix-freezeable-workqueues-implementation.patch
workqueue-fix-flush_workqueue-vs-cpu_dead-race.patch
workqueue-dont-clear-cwq-thread-until-it-exits.patch
workqueue-dont-migrate-pending-works-from-the-dead-cpu.patch
workqueue-kill-run_scheduled_work.patch
workqueue-dont-save-interrupts-in-run_workqueue.patch
workqueue-make-cancel_rearming_delayed_workqueue-work-on-idle-dwork.patch
workqueue-introduce-cpu_singlethread_map.patch
workqueue-introduce-workqueue_struct-singlethread.patch
workqueue-make-init_workqueues-__init.patch
make-queue_delayed_work-friendly-to-flush_fork.patch
unify-queue_delayed_work-and-queue_delayed_work_on.patch
workqueue-introduce-wq_per_cpu-helper.patch
make-cancel_rearming_delayed_work-work-on-any-workqueue-not-just-keventd_wq.patch
ipvs-flush-defense_work-before-module-unload.patch
workqueue-kill-noautorel-works.patch
worker_thread-dont-play-with-signals.patch
worker_thread-fix-racy-try_to_freeze-usage.patch
zap_other_threads-remove-unneeded-exit_signal-change.patch
slab-shutdown-cache_reaper-when-cpu-goes-down.patch
unify-flush_work-flush_work_keventd-and-rename-it-to-cancel_work_sync.patch
____call_usermodehelper-dont-flush_signals.patch
freezer-read-pf_borrowed_mm-in-a-nonracy-way.patch
freezer-close-theoretical-race-between-refrigerator-and-thaw_tasks.patch
freezer-remove-pf_nofreeze-from-rcutorture-thread.patch
freezer-remove-pf_nofreeze-from-bluetooth-threads.patch
freezer-add-try_to_freeze-calls-to-all-kernel-threads.patch
freezer-fix-vfork-problem.patch
freezer-take-kernel_execve-into-consideration.patch
reduce-reparent_to_init.patch
make-kernel-threads-invisible-to-sbin-init.patch
reparent-kernel-threads-to-swapper.patch
only-send-pdeath_signal-when-getppid-changes.patch
dont-init-pgrp-and-__session-in-init_signals.patch
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