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authorSteven J. Hill <steven.hill@cavium.com>2018-03-28 16:01:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-03-28 13:42:05 -1000
commitc7f26ccfb2c31eb1bf810ba13d044fcf583232db (patch)
tree394207a8faa79d45f9d0a85b9fc90af19d65eca3
parent299815a4fba9f3c7a81434dba0072148f1690608 (diff)
mm/vmstat.c: fix vmstat_update() preemption BUG
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@cavium.com 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>
-rw-r--r--mm/vmstat.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 40b2db6db6b1..33581be705f0 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1839,9 +1839,11 @@ static void vmstat_update(struct work_struct *w)
* 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();
}
}