Messages in this thread Patch in this message | | | Date | Wed, 24 Nov 2010 20:09:48 -0500 | From | Dave Jones <> | Subject | rcu_read_lock/unlock protect find_task_by_vpid call in posix_cpu_timer_create |
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=================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- kernel/pid.c:419 invoked rcu_dereference_check() without protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 1 1 lock held by scrashme/20820: #0: (tasklist_lock){.?.?..}, at: [<ffffffff8106e30f>] posix_cpu_timer_create+0x50/0xee
stack backtrace: Pid: 20820, comm: scrashme Not tainted 2.6.37-rc3+ #7 Call Trace: [<ffffffff8107cfd5>] lockdep_rcu_dereference+0x9d/0xa5 [<ffffffff81069d08>] find_task_by_pid_ns+0x44/0x5d [<ffffffff81069d43>] find_task_by_vpid+0x22/0x24 [<ffffffff8106e32d>] posix_cpu_timer_create+0x6e/0xee [<ffffffff8106eb88>] do_cpu_nanosleep+0x83/0x1ad [<ffffffff8106f50a>] posix_cpu_nsleep+0x6d/0xf6 [<ffffffff810f9a64>] ? might_fault+0xa5/0xac [<ffffffff810f9a1b>] ? might_fault+0x5c/0xac [<ffffffff8106bf57>] sys_clock_nanosleep+0x7c/0xcb [<ffffffff81009cb2>] system_call_fastpath+0x16/0x1b
Signed-off-by: Dave Jones <davej@redhat.com>
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index 6842eeb..2658955 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -391,6 +391,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) INIT_LIST_HEAD(&new_timer->it.cpu.entry); read_lock(&tasklist_lock); + rcu_read_lock(); if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) { if (pid == 0) { p = current; @@ -414,6 +415,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) } else { ret = -EINVAL; } + rcu_read_unlock(); read_unlock(&tasklist_lock); return ret;
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