diff options
| author | Phil Auld <pauld@redhat.com> | 2022-11-17 11:23:28 -0500 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2022-12-02 12:43:02 +0100 |
| commit | 64ea6e44f85b9b75925ebe1ba0e6e8430cc4e06f (patch) | |
| tree | ceeebffbb2562c110a25e7b567b0c3bc6b5fd1fe /kernel/cpu.c | |
| parent | b7b275e60bcd5f89771e865a8239325f86d9927d (diff) | |
cpu/hotplug: Make target_store() a nop when target == state
Writing the current state back in hotplug/target calls cpu_down()
which will set cpu dying even when it isn't and then nothing will
ever clear it. A stress test that reads values and writes them back
for all cpu device files in sysfs will trigger the BUG() in
select_fallback_rq once all cpus are marked as dying.
kernel/cpu.c::target_store()
...
if (st->state < target)
ret = cpu_up(dev->id, target);
else
ret = cpu_down(dev->id, target);
cpu_down() -> cpu_set_state()
bool bringup = st->state < target;
...
if (cpu_dying(cpu) != !bringup)
set_cpu_dying(cpu, !bringup);
Fix this by letting state==target fall through in the target_store()
conditional. Also make sure st->target == target in that case.
Fixes: 757c989b9994 ("cpu/hotplug: Make target state writeable")
Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20221117162329.3164999-2-pauld@redhat.com
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index bbad5e375d3b..979de993f853 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -2326,8 +2326,10 @@ static ssize_t target_store(struct device *dev, struct device_attribute *attr, if (st->state < target) ret = cpu_up(dev->id, target); - else + else if (st->state > target) ret = cpu_down(dev->id, target); + else if (WARN_ON(st->target != target)) + st->target = target; out: unlock_device_hotplug(); return ret ? ret : count; |