The patch titled
From: Oleg Nesterov <oleg@xxxxxxxxxx>
has been added to the -mm tree. Its filename is
do_task_stat-dont-take-tty_mutex.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: From: Oleg Nesterov <oleg@xxxxxxxxxx>
Depends on
tty-signal-tty-locking.patch
->signal->tty is protected by ->siglock, no need to take the global tty_mutex.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/proc/array.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)
diff -puN fs/proc/array.c~do_task_stat-dont-take-tty_mutex fs/proc/array.c
--- a/fs/proc/array.c~do_task_stat-dont-take-tty_mutex
+++ a/fs/proc/array.c
@@ -346,20 +346,13 @@ static int do_task_stat(struct task_stru
sigemptyset(&sigcatch);
cutime = cstime = utime = stime = cputime_zero;
- mutex_lock(&tty_mutex);
rcu_read_lock();
if (lock_task_sighand(task, &flags)) {
struct signal_struct *sig = task->signal;
- struct tty_struct *tty = sig->tty;
- if (tty) {
- /*
- * sig->tty is not stable, but tty_mutex
- * protects us from release_dev(tty)
- */
- barrier();
- tty_pgrp = tty->pgrp;
- tty_nr = new_encode_dev(tty_devnum(tty));
+ if (sig->tty) {
+ tty_pgrp = sig->tty->pgrp;
+ tty_nr = new_encode_dev(tty_devnum(sig->tty));
}
num_threads = atomic_read(&sig->count);
@@ -395,7 +388,6 @@ static int do_task_stat(struct task_stru
unlock_task_sighand(task, &flags);
}
rcu_read_unlock();
- mutex_unlock(&tty_mutex);
if (!whole || num_threads<2)
wchan = get_wchan(task);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
tty-signal-tty-locking.patch
do_task_stat-dont-take-tty_mutex.patch
pidhash-temporary-debug-checks.patch
-
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