The patch titled
set EXIT_DEAD state in do_exit(), not in schedule()
has been added to the -mm tree. Its filename is
set-exit_dead-state-in-do_exit-not-in-schedule.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: set EXIT_DEAD state in do_exit(), not in schedule()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
schedule() checks PF_DEAD on every context switch and sets ->state = EXIT_DEAD
to ensure that the exiting task will be deactivated. Note that this EXIT_DEAD
is in fact a "random" value, we can use any bit except normal TASK_XXX values.
It is better to set this state in do_exit() along with PF_DEAD flag and remove
that check in schedule().
We are safe wrt concurrent try_to_wake_up() (for example ptrace, tkill), it
can not change task's ->state: the 'state' argument of try_to_wake_up() can't
have EXIT_DEAD bit. And in case when try_to_wake_up() sees a stale value of
->state == TASK_RUNNING it will do nothing.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/exit.c | 1 +
kernel/sched.c | 3 ---
2 files changed, 1 insertion(+), 3 deletions(-)
diff -puN kernel/exit.c~set-exit_dead-state-in-do_exit-not-in-schedule kernel/exit.c
--- a/kernel/exit.c~set-exit_dead-state-in-do_exit-not-in-schedule
+++ a/kernel/exit.c
@@ -958,6 +958,7 @@ fastcall NORET_TYPE void do_exit(long co
preempt_disable();
BUG_ON(tsk->flags & PF_DEAD);
tsk->flags |= PF_DEAD;
+ tsk->state = EXIT_DEAD;
schedule();
BUG();
diff -puN kernel/sched.c~set-exit_dead-state-in-do_exit-not-in-schedule kernel/sched.c
--- a/kernel/sched.c~set-exit_dead-state-in-do_exit-not-in-schedule
+++ a/kernel/sched.c
@@ -3311,9 +3311,6 @@ need_resched_nonpreemptible:
spin_lock_irq(&rq->lock);
- if (unlikely(prev->flags & PF_DEAD))
- prev->state = EXIT_DEAD;
-
switch_count = &prev->nivcsw;
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
switch_count = &prev->nvcsw;
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
for-2618-revert-drop-tasklist-lock-in-do_sched_setscheduler.patch
futex_find_get_task-remove-an-obscure-exit_zombie-check.patch
pid-implement-transfer_pid-and-use-it-to-simplify-de_thread.patch
pid-remove-temporary-debug-code-in-attach_pid.patch
rtmutex-clean-up-and-remove-some-extra-spinlocks.patch
rtmutex-clean-up-and-remove-some-extra-spinlocks-more.patch
elf_core_dump-dont-take-tasklist_lock.patch
elf_fdpic_core_dump-dont-take-tasklist_lock.patch
has_stopped_jobs-cleanup.patch
__dequeue_signal-cleanup.patch
do_sched_setscheduler-dont-take-tasklist_lock.patch
introduce-is_rt_policy-helper.patch
sched_setscheduler-fix-policy-checks.patch
reparent_to_init-use-has_rt_policy.patch
copy_process-cosmetic-ioprio-tweak.patch
futex_find_get_task-dont-take-tasklist_lock.patch
sys_get_robust_list-dont-take-tasklist_lock.patch
set-exit_dead-state-in-do_exit-not-in-schedule.patch
kill-pf_dead-flag.patch
introduce-task_dead-state.patch
simplify-pid-iterators.patch
pidhash-temporary-debug-checks.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
