diff options
| author | Tejun Heo <htejun@gmail.com> | 2016-06-16 15:35:04 -0400 |
|---|---|---|
| committer | Georg Veichtlbauer <georg@vware.at> | 2023-07-16 12:47:43 +0200 |
| commit | c9999f04236e640bc82b2085cadca8487184bc76 (patch) | |
| tree | a317eda097de4aed45b9229a787561f45092308b | |
| parent | b9b6bc6ea3c06ab2edac96db7a3f9e51c9e459d1 (diff) | |
sched/core: Allow kthreads to fall back to online && !active cpus
During CPU hotplug, CPU_ONLINE callbacks are run while the CPU is
online but not active. A CPU_ONLINE callback may create or bind a
kthread so that its cpus_allowed mask only allows the CPU which is
being brought online. The kthread may start executing before the CPU
is made active and can end up in select_fallback_rq().
In such cases, the expected behavior is selecting the CPU which is
coming online; however, because select_fallback_rq() only chooses from
active CPUs, it determines that the task doesn't have any viable CPU
in its allowed mask and ends up overriding it to cpu_possible_mask.
CPU_ONLINE callbacks should be able to put kthreads on the CPU which
is coming online. Update select_fallback_rq() so that it follows
cpu_online() rather than cpu_active() for kthreads.
Reported-by: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Tested-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Change-Id: I562dcc53717b1f2f8324abffb652b91592ba8d5c
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@fb.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20160616193504.GB3262@mtj.duckdns.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/sched/core.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 3c64cd08e8e2..e83959592d6c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1654,9 +1654,9 @@ static int select_fallback_rq(int cpu, struct task_struct *p, bool allow_iso) for (;;) { /* Any allowed, online CPU? */ for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { - if (!cpu_online(dest_cpu)) + if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu)) continue; - if (!cpu_active(dest_cpu)) + if (!cpu_online(dest_cpu)) continue; if (cpu_isolated(dest_cpu)) { if (allow_iso) |