The patch titled
futex_find_get_task(): don't take tasklist_lock
has been added to the -mm tree. Its filename is
futex_find_get_task-dont-take-tasklist_lock.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: futex_find_get_task(): don't take tasklist_lock
From: Oleg Nesterov <oleg@xxxxxxxxxx>
It is ok to do find_task_by_pid() + get_task_struct() under
rcu_read_lock(), we cand drop tasklist_lock.
Note that testing of ->exit_state is racy with or without tasklist anyway.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/futex.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN kernel/futex.c~futex_find_get_task-dont-take-tasklist_lock kernel/futex.c
--- a/kernel/futex.c~futex_find_get_task-dont-take-tasklist_lock
+++ a/kernel/futex.c
@@ -389,7 +389,7 @@ static struct task_struct * futex_find_g
{
struct task_struct *p;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_task_by_pid(pid);
if (!p)
goto out_unlock;
@@ -403,7 +403,7 @@ static struct task_struct * futex_find_g
}
get_task_struct(p);
out_unlock:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return p;
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
for-2618-revert-drop-tasklist-lock-in-do_sched_setscheduler.patch
pid-implement-transfer_pid-and-use-it-to-simplify-de_thread.patch
pid-remove-temporary-debug-code-in-attach_pid.patch
rtmutex-clean-up-and-remove-some-extra-spinlocks.patch
rtmutex-clean-up-and-remove-some-extra-spinlocks-more.patch
elf_core_dump-dont-take-tasklist_lock.patch
elf_fdpic_core_dump-dont-take-tasklist_lock.patch
has_stopped_jobs-cleanup.patch
__dequeue_signal-cleanup.patch
do_sched_setscheduler-dont-take-tasklist_lock.patch
introduce-is_rt_policy-helper.patch
sched_setscheduler-fix-policy-checks.patch
reparent_to_init-use-has_rt_policy.patch
copy_process-cosmetic-ioprio-tweak.patch
futex_find_get_task-remove-an-obscure-exit_zombie-check.patch
futex_find_get_task-dont-take-tasklist_lock.patch
sys_get_robust_list-dont-take-tasklist_lock.patch
simplify-pid-iterators.patch
pidhash-temporary-debug-checks.patch
-
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