diff options
author | Phil Auld <pauld@redhat.com> | 2022-11-17 11:23:28 -0500 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-01-14 10:15:20 +0100 |
commit | 270700e7df960fa227c2106718578302bab8ce44 (patch) | |
tree | c61d39e7e120be8fd0ca64b268aacc5571bcd563 /kernel | |
parent | fc89b8853aec7ee07b31ae45e8f980369a79871d (diff) |
cpu/hotplug: Make target_store() a nop when target == state
[ Upstream commit 64ea6e44f85b9b75925ebe1ba0e6e8430cc4e06f ]
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
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
-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 3c9ee966c56a..008b50da2224 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -2231,8 +2231,10 @@ static ssize_t write_cpuhp_target(struct device *dev, 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; |