The patch titled
Subject: sched: do not use cpu_to_node() to find an offlined cpu's node.
has been removed from the -mm tree. Its filename was
sched-do-not-use-cpu_to_node-to-find-an-offlined-cpus-node.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Subject: sched: do not use cpu_to_node() to find an offlined cpu's node.
If a cpu is offline, its nid will be set to -1, and cpu_to_node(cpu) will
return -1. As a result, cpumask_of_node(nid) will return NULL. In this
case, find_next_bit() in for_each_cpu will get a NULL pointer and cause
panic.
Here is a call trace:
[ 609.824017] Call Trace:
[ 609.824017] <IRQ>
[ 609.824017] [<ffffffff810b0721>] select_fallback_rq+0x71/0x190
[ 609.824017] [<ffffffff810b086e>] ? try_to_wake_up+0x2e/0x2f0
[ 609.824017] [<ffffffff810b0b0b>] try_to_wake_up+0x2cb/0x2f0
[ 609.824017] [<ffffffff8109da08>] ? __run_hrtimer+0x78/0x320
[ 609.824017] [<ffffffff810b0b85>] wake_up_process+0x15/0x20
[ 609.824017] [<ffffffff8109ce62>] hrtimer_wakeup+0x22/0x30
[ 609.824017] [<ffffffff8109da13>] __run_hrtimer+0x83/0x320
[ 609.824017] [<ffffffff8109ce40>] ? update_rmtp+0x80/0x80
[ 609.824017] [<ffffffff8109df56>] hrtimer_interrupt+0x106/0x280
[ 609.824017] [<ffffffff810a72c8>] ? sd_free_ctl_entry+0x68/0x70
[ 609.824017] [<ffffffff8167cf39>] smp_apic_timer_interrupt+0x69/0x99
[ 609.824017] [<ffffffff8167be2f>] apic_timer_interrupt+0x6f/0x80
There is a hrtimer process sleeping, whose cpu has already been offlined.
When it is waken up, it tries to find another cpu to run, and get a -1
nid. As a result, cpumask_of_node(-1) returns NULL, and causes ernel
panic.
This patch fixes this problem by judging if the nid is -1. If nid is not
-1, a cpu on the same node will be picked. Else, a online cpu on another
node will be picked.
Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Jiang Liu <liuj97@xxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sched/core.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)
diff -puN kernel/sched/core.c~sched-do-not-use-cpu_to_node-to-find-an-offlined-cpus-node kernel/sched/core.c
--- a/kernel/sched/core.c~sched-do-not-use-cpu_to_node-to-find-an-offlined-cpus-node
+++ a/kernel/sched/core.c
@@ -1132,18 +1132,28 @@ EXPORT_SYMBOL_GPL(kick_process);
*/
static int select_fallback_rq(int cpu, struct task_struct *p)
{
- const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
+ int nid = cpu_to_node(cpu);
+ const struct cpumask *nodemask = NULL;
enum { cpuset, possible, fail } state = cpuset;
int dest_cpu;
- /* Look for allowed, online CPU in same node. */
- for_each_cpu(dest_cpu, nodemask) {
- if (!cpu_online(dest_cpu))
- continue;
- if (!cpu_active(dest_cpu))
- continue;
- if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
- return dest_cpu;
+ /*
+ * If the node that the cpu is on has been offlined, cpu_to_node()
+ * will return -1. There is no cpu on the node, and we should
+ * select the cpu on the other node.
+ */
+ if (nid != -1) {
+ nodemask = cpumask_of_node(nid);
+
+ /* Look for allowed, online CPU in same node. */
+ for_each_cpu(dest_cpu, nodemask) {
+ if (!cpu_online(dest_cpu))
+ continue;
+ if (!cpu_active(dest_cpu))
+ continue;
+ if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
+ return dest_cpu;
+ }
}
for (;;) {
_
Patches currently in -mm which might be from tangchen@xxxxxxxxxxxxxx are
origin.patch
linux-next.patch
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