From: Greg Kroah-Hartman Date: Tue, 7 Feb 2012 01:05:36 +0000 (-0800) Subject: 3.0-stable patches X-Git-Tag: v3.0.21~18 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8932afdab86b507be03600bf02be15816755e91a;p=thirdparty%2Fkernel%2Fstable-queue.git 3.0-stable patches added patches: sched-rt-fix-task-stack-corruption-under-__arch_want_interrupts_on_ctxsw.patch --- diff --git a/queue-3.0/sched-rt-fix-task-stack-corruption-under-__arch_want_interrupts_on_ctxsw.patch b/queue-3.0/sched-rt-fix-task-stack-corruption-under-__arch_want_interrupts_on_ctxsw.patch new file mode 100644 index 00000000000..35039a7a470 --- /dev/null +++ b/queue-3.0/sched-rt-fix-task-stack-corruption-under-__arch_want_interrupts_on_ctxsw.patch @@ -0,0 +1,91 @@ +From cb297a3e433dbdcf7ad81e0564e7b804c941ff0d Mon Sep 17 00:00:00 2001 +From: Chanho Min +Date: Thu, 5 Jan 2012 20:00:19 +0900 +Subject: sched/rt: Fix task stack corruption under __ARCH_WANT_INTERRUPTS_ON_CTXSW + +From: Chanho Min + +commit cb297a3e433dbdcf7ad81e0564e7b804c941ff0d upstream. + +This issue happens under the following conditions: + + 1. preemption is off + 2. __ARCH_WANT_INTERRUPTS_ON_CTXSW is defined + 3. RT scheduling class + 4. SMP system + +Sequence is as follows: + + 1.suppose current task is A. start schedule() + 2.task A is enqueued pushable task at the entry of schedule() + __schedule + prev = rq->curr; + ... + put_prev_task + put_prev_task_rt + enqueue_pushable_task + 4.pick the task B as next task. + next = pick_next_task(rq); + 3.rq->curr set to task B and context_switch is started. + rq->curr = next; + 4.At the entry of context_swtich, release this cpu's rq->lock. + context_switch + prepare_task_switch + prepare_lock_switch + raw_spin_unlock_irq(&rq->lock); + 5.Shortly after rq->lock is released, interrupt is occurred and start IRQ context + 6.try_to_wake_up() which called by ISR acquires rq->lock + try_to_wake_up + ttwu_remote + rq = __task_rq_lock(p) + ttwu_do_wakeup(rq, p, wake_flags); + task_woken_rt + 7.push_rt_task picks the task A which is enqueued before. + task_woken_rt + push_rt_tasks(rq) + next_task = pick_next_pushable_task(rq) + 8.At find_lock_lowest_rq(), If double_lock_balance() returns 0, + lowest_rq can be the remote rq. + (But,If preemption is on, double_lock_balance always return 1 and it + does't happen.) + push_rt_task + find_lock_lowest_rq + if (double_lock_balance(rq, lowest_rq)).. + 9.find_lock_lowest_rq return the available rq. task A is migrated to + the remote cpu/rq. + push_rt_task + ... + deactivate_task(rq, next_task, 0); + set_task_cpu(next_task, lowest_rq->cpu); + activate_task(lowest_rq, next_task, 0); + 10. But, task A is on irq context at this cpu. + So, task A is scheduled by two cpus at the same time until restore from IRQ. + Task A's stack is corrupted. + +To fix it, don't migrate an RT task if it's still running. + +Signed-off-by: Chanho Min +Signed-off-by: Peter Zijlstra +Acked-by: Steven Rostedt +Link: http://lkml.kernel.org/r/CAOAMb1BHA=5fm7KTewYyke6u-8DP0iUuJMpgQw54vNeXFsGpoQ@mail.gmail.com +Signed-off-by: Ingo Molnar +Signed-off-by: Greg Kroah-Hartman + +--- + kernel/sched_rt.c | 5 +++++ + 1 file changed, 5 insertions(+) + +--- a/kernel/sched_rt.c ++++ b/kernel/sched_rt.c +@@ -1390,6 +1390,11 @@ static int push_rt_task(struct rq *rq) + if (!next_task) + return 0; + ++#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW ++ if (unlikely(task_running(rq, next_task))) ++ return 0; ++#endif ++ + retry: + if (unlikely(next_task == rq->curr)) { + WARN_ON(1); diff --git a/queue-3.0/series b/queue-3.0/series index 2b4d2fb89ab..9024a5e65b7 100644 --- a/queue-3.0/series +++ b/queue-3.0/series @@ -20,3 +20,4 @@ mm-compaction-check-pfn_valid-when-entering-a-new-max_order_nr_pages-block-durin drm-radeon-set-desktop_height-register-to-the-framebuffer-not-mode-height.patch drm-nouveau-gem-fix-fence_sync-race-oops.patch drm-radeon-kms-disable-output-polling-when-suspended.patch +sched-rt-fix-task-stack-corruption-under-__arch_want_interrupts_on_ctxsw.patch