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| author | Tianchen Ding <dtcccc@linux.alibaba.com> | 2024-12-31 13:50:20 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-02-08 10:00:58 +0100 |
| commit | 822fd766e7ef0a0d15144e410a7fdacf0162edf4 (patch) | |
| tree | 87f4960e0446868e945d091072408278865b8c94 /kernel | |
| parent | 80dfd698b2002862d3e17021c6c5e9a0b162c987 (diff) | |
| download | linux-822fd766e7ef0a0d15144e410a7fdacf0162edf4.tar.gz linux-822fd766e7ef0a0d15144e410a7fdacf0162edf4.tar.bz2 linux-822fd766e7ef0a0d15144e410a7fdacf0162edf4.zip | |
sched: Fix race between yield_to() and try_to_wake_up()
[ Upstream commit 5d808c78d97251af1d3a3e4f253e7d6c39fd871e ]
We met a SCHED_WARN in set_next_buddy():
__warn_printk
set_next_buddy
yield_to_task_fair
yield_to
kvm_vcpu_yield_to [kvm]
...
After a short dig, we found the rq_lock held by yield_to() may not
be exactly the rq that the target task belongs to. There is a race
window against try_to_wake_up().
CPU0 target_task
blocking on CPU1
lock rq0 & rq1
double check task_rq == p_rq, ok
woken to CPU2 (lock task_pi & rq2)
task_rq = rq2
yield_to_task_fair (w/o lock rq2)
In this race window, yield_to() is operating the task w/o the correct
lock. Fix this by taking task pi_lock first.
Fixes: d95f41220065 ("sched: Add yield_to(task, preempt) functionality")
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20241231055020.6521-1-dtcccc@linux.alibaba.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/syscalls.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c index ff0e5ab4e37c..943406c4ee86 100644 --- a/kernel/sched/syscalls.c +++ b/kernel/sched/syscalls.c @@ -1433,7 +1433,7 @@ int __sched yield_to(struct task_struct *p, bool preempt) struct rq *rq, *p_rq; int yielded = 0; - scoped_guard (irqsave) { + scoped_guard (raw_spinlock_irqsave, &p->pi_lock) { rq = this_rq(); again: |