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exit: make setting exit_state consistent
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Since commit b191d64 ("pidfd: fix a poll race when setting exit_state")
we unconditionally set exit_state to EXIT_ZOMBIE before calling into
do_notify_parent(). This was done to eliminate a race when querying
exit_state in do_notify_pidfd().
Back then we decided to do the absolute minimal thing to fix this and
not touch the rest of the exit_notify() function where exit_state is
set.
Since this fix has not caused any issues change the setting of
exit_state to EXIT_DEAD in the autoreap case to account for the fact hat
exit_state is set to EXIT_ZOMBIE unconditionally. This fix was planned
but also explicitly requested in [1] and makes the whole code more
consistent.

/* References */
[1]: https://lore.kernel.org/lkml/CAHk-=wigcxGFR2szue4wavJtH5cYTTeNES=toUBVGsmX0rzX+g@mail.gmail.com

Signed-off-by: Christian Brauner <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Cc: Linus Torvalds <[email protected]>
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brauner committed Jul 30, 2019
1 parent 1caf7d5 commit 30b692d
Showing 1 changed file with 3 additions and 2 deletions.
5 changes: 3 additions & 2 deletions kernel/exit.c
Original file line number Diff line number Diff line change
Expand Up @@ -734,9 +734,10 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
autoreap = true;
}

tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
if (tsk->exit_state == EXIT_DEAD)
if (autoreap) {
tsk->exit_state = EXIT_DEAD;
list_add(&tsk->ptrace_entry, &dead);
}

/* mt-exec, de_thread() is waiting for group leader */
if (unlikely(tsk->signal->notify_count < 0))
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