The patch titled
__exit_signal: don't take rcu lock
has been added to the -mm tree. Its filename is
__exit_signal-dont-take-rcu-lock.patch
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See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: __exit_signal: don't take rcu lock
From: Oleg Nesterov <oleg@xxxxxxxxxx>
There is no reason for rcu_read_lock() in __exit_signal(). tsk->sighand
can only be changed if tsk does exec, obviously this is not possible.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 2 --
1 file changed, 2 deletions(-)
diff -puN kernel/exit.c~__exit_signal-dont-take-rcu-lock kernel/exit.c
--- a/kernel/exit.c~__exit_signal-dont-take-rcu-lock
+++ a/kernel/exit.c
@@ -84,7 +84,6 @@ static void __exit_signal(struct task_st
BUG_ON(!sig);
BUG_ON(!atomic_read(&sig->count));
- rcu_read_lock();
sighand = rcu_dereference(tsk->sighand);
spin_lock(&sighand->siglock);
@@ -135,7 +134,6 @@ static void __exit_signal(struct task_st
tsk->signal = NULL;
tsk->sighand = NULL;
spin_unlock(&sighand->siglock);
- rcu_read_unlock();
__cleanup_sighand(sighand);
clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
vt-fix-vc_resize-locking.patch
uml-activate_mm-remove-the-dead-pf_borrowed_mm-check.patch
posix-timers-timer_delete-remove-the-bogus-it_process-=-null-check.patch
posix-timers-release_posix_timer-kill-the-bogus-put_task_struct-it_process.patch
signals-collect_signal-remove-the-unneeded-sigismember-check.patch
signals-collect_signal-simplify-the-still_pending-logic.patch
signals-change-collect_signal-to-return-void.patch
__exit_signal-dont-take-rcu-lock.patch
signals-dequeue_signal-dont-check-signal_group_exit-when-setting-signal_stop_dequeued.patch
signals-do_signal_stop-kill-the-signal_unkillable-check.patch
coredump-zap_threads-comments-use-while_each_thread.patch
distinct-tgid-tid-i-o-statistics.patch
--
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