From: Peter Zijlstra <peterz@infradead.org>
To: gor@linux.ibm.com, jpoimboe@redhat.com, jikos@kernel.org,
mbenes@suse.cz, pmladek@suse.com, mingo@kernel.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
joe.lawrence@redhat.com, fweisbec@gmail.com, tglx@linutronix.de,
hca@linux.ibm.com, svens@linux.ibm.com, sumanthk@linux.ibm.com,
live-patching@vger.kernel.org, paulmck@kernel.org
Subject: [RFC][PATCH 7/7] livepatch,context_tracking: Avoid disturbing NOHZ_FULL tasks
Date: Wed, 22 Sep 2021 13:05:13 +0200 [thread overview]
Message-ID: <20210922110836.304335737@infradead.org> (raw)
In-Reply-To: 20210922110506.703075504@infradead.org
When a task is stuck in NOHZ_FULL usermode, we can simply mark the
livepatch state complete.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/livepatch/transition.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -270,13 +270,24 @@ static int klp_check_task(struct task_st
{
int ret;
- if (task_curr(task))
+ if (task_curr(task)) {
+ if (context_tracking_state_cpu(task_cpu(task)) == CONTEXT_USER) {
+ /*
+ * If we observe the CPU being in USER context, they
+ * must issue an smp_mb() before doing much kernel
+ * space and as such will observe the patched state,
+ * mark it clean.
+ */
+ goto complete;
+ }
return -EBUSY;
+ }
ret = klp_check_stack(task, arg);
if (ret)
return ret;
+complete:
clear_tsk_thread_flag(task, TIF_PATCH_PENDING);
task->patch_state = klp_target_state;
return 0;
next prev parent reply other threads:[~2021-09-22 11:11 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 11:05 [RFC][PATCH 0/7] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL cpus Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 1/7] sched,rcu: Rework try_invoke_on_locked_down_task() Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 2/7] sched: Fix task_try_func() Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 3/7] sched,livepatch: Use task_try_func() Peter Zijlstra
2021-09-23 12:05 ` Petr Mladek
2021-09-23 13:17 ` Peter Zijlstra
2021-09-23 13:47 ` Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 4/7] sched: Simplify wake_up_*idle*() Peter Zijlstra
2021-09-22 11:05 ` [RFC][PATCH 5/7] sched,livepatch: Use wake_up_if_idle() Peter Zijlstra
2021-09-22 13:05 ` Miroslav Benes
2021-09-23 12:19 ` Petr Mladek
2021-09-22 11:05 ` [RFC][PATCH 6/7] context_tracking: Provide SMP ordering using RCU Peter Zijlstra
2021-09-22 15:17 ` Paul E. McKenney
2021-09-22 19:33 ` Peter Zijlstra
2021-09-22 19:47 ` Peter Zijlstra
2021-09-22 19:59 ` Paul E. McKenney
2021-09-22 19:53 ` Paul E. McKenney
2021-09-22 20:02 ` Peter Zijlstra
2021-09-23 12:10 ` Petr Mladek
2021-09-24 18:57 ` Joel Savitz
2021-09-27 14:33 ` Petr Mladek
2021-09-22 11:05 ` Peter Zijlstra [this message]
2021-09-23 13:14 ` [RFC][PATCH 7/7] livepatch,context_tracking: Avoid disturbing NOHZ_FULL tasks Petr Mladek
2021-09-23 13:28 ` Peter Zijlstra
2021-09-24 7:33 ` Petr Mladek
2021-09-23 13:22 ` [RFC][PATCH 0/7] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL cpus Petr Mladek
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