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Commit c394cc9f authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

[PATCH] introduce TASK_DEAD state 



I am not sure about this patch, I am asking Ingo to take a decision.

task_struct->state == EXIT_DEAD is a very special case, to avoid a confusion
it makes sense to introduce a new state, TASK_DEAD, while EXIT_DEAD should
live only in ->exit_state as documented in sched.h.

Note that this state is not visible to user-space, get_task_state() masks off
unsuitable states.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 55a101f8

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -148,6 +148,7 @@ extern unsigned long weighted_cpuload(const int cpu); 
#define EXIT_DEAD		32

/* in tsk->state again */

#define TASK_NONINTERACTIVE	64

#define TASK_DEAD		128



#define __set_task_state(tsk, state_value)		\

	do { (tsk)->state = (state_value); } while (0)

kernel/exit.c

+1 −1
Original line number Diff line number Diff line
@@ -955,7 +955,7 @@ fastcall NORET_TYPE void do_exit(long code) 


	preempt_disable();

	/* causes final put_task_struct in finish_task_switch(). */

	tsk->state = EXIT_DEAD;

	tsk->state = TASK_DEAD;



	schedule();

	BUG();

kernel/sched.c

+4 −4
Original line number Diff line number Diff line
@@ -1761,10 +1761,10 @@ static inline void finish_task_switch(struct rq *rq, struct task_struct *prev) 


	/*

	 * A task struct has one reference for the use as "current".

	 * If a task dies, then it sets EXIT_DEAD in tsk->state and calls

	 * If a task dies, then it sets TASK_DEAD in tsk->state and calls

	 * schedule one last time. The schedule call will never return, and

	 * the scheduled task must drop that reference.

	 * The test for EXIT_DEAD must occur while the runqueue locks are

	 * The test for TASK_DEAD must occur while the runqueue locks are

	 * still held, otherwise prev could be scheduled on another cpu, die

	 * there before we look at prev->state, and then the reference would

	 * be dropped twice.
@@ -1775,7 +1775,7 @@ static inline void finish_task_switch(struct rq *rq, struct task_struct *prev) 
	finish_lock_switch(rq, prev);

	if (mm)

		mmdrop(mm);

	if (unlikely(prev_state == EXIT_DEAD)) {

	if (unlikely(prev_state == TASK_DEAD)) {

		/*

		 * Remove function-return probe instances associated with this

		 * task and put them back on the free list.
@@ -5153,7 +5153,7 @@ static void migrate_dead(unsigned int dead_cpu, struct task_struct *p) 
	BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD);



	/* Cannot have done final schedule yet: would have vanished. */

	BUG_ON(p->state == EXIT_DEAD);

	BUG_ON(p->state == TASK_DEAD);



	get_task_struct(p);

mm/oom_kill.c

+1 −1
Original line number Diff line number Diff line
@@ -227,7 +227,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints) 
						p->flags & PF_EXITING;

		if (releasing) {

			/* TASK_DEAD tasks have already released their mm */

			if (p->state == EXIT_DEAD)

			if (p->state == TASK_DEAD)

				continue;

			if (p->flags & PF_EXITING && p == current) {

				chosen = p;