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| author | Koichiro Den <koichiro.den@canonical.com> | 2024-12-21 04:33:20 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-12-31 02:59:10 +0100 |
| commit | adcfb264c3ed51fbbf5068ddf10d309a63683868 (patch) | |
| tree | 4ea1e244e36491fd482c92017b28421f711c6cad /mm | |
| parent | mm: shmem: fix the update of 'shmem_falloc->nr_unswapped' (diff) | |
| download | linux-adcfb264c3ed51fbbf5068ddf10d309a63683868.tar.xz linux-adcfb264c3ed51fbbf5068ddf10d309a63683868.zip | |
vmstat: disable vmstat_work on vmstat_cpu_down_prep()
Even after mm/vmstat:online teardown, shepherd may still queue work for
the dying cpu until the cpu is removed from online mask. While it's quite
rare, this means that after unbind_workers() unbinds a per-cpu kworker, it
potentially runs vmstat_update for the dying CPU on an irrelevant cpu
before entering atomic AP states. When CONFIG_DEBUG_PREEMPT=y, it results
in the following error with the backtrace.
BUG: using smp_processor_id() in preemptible [00000000] code: \
kworker/7:3/1702
caller is refresh_cpu_vm_stats+0x235/0x5f0
CPU: 0 UID: 0 PID: 1702 Comm: kworker/7:3 Tainted: G
Tainted: [N]=TEST
Workqueue: mm_percpu_wq vmstat_update
Call Trace:
<TASK>
dump_stack_lvl+0x8d/0xb0
check_preemption_disabled+0xce/0xe0
refresh_cpu_vm_stats+0x235/0x5f0
vmstat_update+0x17/0xa0
process_one_work+0x869/0x1aa0
worker_thread+0x5e5/0x1100
kthread+0x29e/0x380
ret_from_fork+0x2d/0x70
ret_from_fork_asm+0x1a/0x30
</TASK>
So, for mm/vmstat:online, disable vmstat_work reliably on teardown and
symmetrically enable it on startup.
Link: https://lkml.kernel.org/r/20241221033321.4154409-1-koichiro.den@canonical.com
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/vmstat.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c index 4d016314a56c..0889b75cef14 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -2148,13 +2148,14 @@ static int vmstat_cpu_online(unsigned int cpu) if (!node_state(cpu_to_node(cpu), N_CPU)) { node_set_state(cpu_to_node(cpu), N_CPU); } + enable_delayed_work(&per_cpu(vmstat_work, cpu)); return 0; } static int vmstat_cpu_down_prep(unsigned int cpu) { - cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu)); + disable_delayed_work_sync(&per_cpu(vmstat_work, cpu)); return 0; } |