The patch titled
do_task_stat: don't take rcu_read_lock()
has been added to the -mm tree. Its filename is
do_task_stat-dont-take-rcu_read_lock.patch
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See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: do_task_stat: don't take rcu_read_lock()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
lock_task_sighand() was changed, and do_task_stat() doesn't need
rcu_read_lock any longer. sighand->siglock protects all "interesting"
fields.
Except: it doesn't protect ->tty->pgrp, but neither does rcu_read_lock(), this
should be fixed.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/array.c | 2 --
1 file changed, 2 deletions(-)
diff -puN fs/proc/array.c~do_task_stat-dont-take-rcu_read_lock fs/proc/array.c
--- a/fs/proc/array.c~do_task_stat-dont-take-rcu_read_lock
+++ a/fs/proc/array.c
@@ -425,7 +425,6 @@ static int do_task_stat(struct seq_file
cutime = cstime = utime = stime = cputime_zero;
cgtime = gtime = cputime_zero;
- rcu_read_lock();
if (lock_task_sighand(task, &flags)) {
struct signal_struct *sig = task->signal;
@@ -469,7 +468,6 @@ static int do_task_stat(struct seq_file
unlock_task_sighand(task, &flags);
}
- rcu_read_unlock();
if (!whole || num_threads < 2)
wchan = get_wchan(task);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
kthread-synchronization-issues.patch
kthread-add-a-missing-memory-barrier-to-kthread_stop.patch
kthread-call-wake_up_process-without-the-lock-being-held.patch
mmap_region-cleanup-the-final-vma_merge-related-code.patch
remove-unused-variable-from-send_signal.patch
turn-legacy_queue-macro-into-static-inline-function.patch
consolidate-checking-for-ignored-legacy-signals.patch
consolidate-checking-for-ignored-legacy-signals-simplify.patch
signals-do_signal_stop-use-signal_group_exit.patch
signals-do_group_exit-use-signal_group_exit-more-consistently.patch
lock_task_sighand-add-rcu-lock-unlock.patch
k_getrusage-dont-take-rcu_read_lock.patch
do_task_stat-dont-take-rcu_read_lock.patch
workqueues-shrink-cpu_populated_map-when-cpu-dies.patch
workqueues-shrink-cpu_populated_map-when-cpu-dies-fix.patch
cleanup_workqueue_thread-remove-the-unneeded-cpu-parameter.patch
simplify-cpu_hotplug_begin-put_online_cpus.patch
timers-simplify-lockdep-stuff.patch
hrtimers-simplify-lockdep-stuff.patch
kill-double_spin_lock.patch
redo-locking-of-tty-pgrp.patch
procfs-task-exe-symlink.patch
procfs-task-exe-symlink-fix.patch
procfs-task-exe-symlink-fix-2.patch
free_pidmap-turn-it-into-free_pidmapstruct-upid.patch
put_pid-make-sure-we-dont-free-the-live-pid.patch
-
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