4.14-stable review patch. If anyone has any objections, please let me know.
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From: "Steven J. Hill" steven.hill@cavium.com
[ Upstream commit c7f26ccfb2c31eb1bf810ba13d044fcf583232db ]
Attempting to hotplug CPUs with CONFIG_VM_EVENT_COUNTERS enabled can cause vmstat_update() to report a BUG due to preemption not being disabled around smp_processor_id().
Discovered on Ubiquiti EdgeRouter Pro with Cavium Octeon II processor.
BUG: using smp_processor_id() in preemptible [00000000] code: kworker/1:1/269 caller is vmstat_update+0x50/0xa0 CPU: 0 PID: 269 Comm: kworker/1:1 Not tainted 4.16.0-rc4-Cavium-Octeon-00009-gf83bbd5-dirty #1 Workqueue: mm_percpu_wq vmstat_update Call Trace: show_stack+0x94/0x128 dump_stack+0xa4/0xe0 check_preemption_disabled+0x118/0x120 vmstat_update+0x50/0xa0 process_one_work+0x144/0x348 worker_thread+0x150/0x4b8 kthread+0x110/0x140 ret_from_kernel_thread+0x14/0x1c
Link: http://lkml.kernel.org/r/1520881552-25659-1-git-send-email-steven.hill@caviu... Signed-off-by: Steven J. Hill steven.hill@cavium.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: Tejun Heo htejun@gmail.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/vmstat.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1770,9 +1770,11 @@ static void vmstat_update(struct work_st * to occur in the future. Keep on running the * update worker thread. */ + preempt_disable(); queue_delayed_work_on(smp_processor_id(), mm_percpu_wq, this_cpu_ptr(&vmstat_work), round_jiffies_relative(sysctl_stat_interval)); + preempt_enable(); } }