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| author | Zqiang <qiang1.zhang@intel.com> | 2022-05-21 09:56:26 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-06-22 01:57:04 +0300 |
| commit | 92366810644d5675043c792abb70eaf974a77384 (patch) | |
| tree | 8866d7a486532b56194edacbc3e2c51c26be5360 /kernel/rcu | |
| parent | 8c0666d320f2fff6bc7cf76422bfbe90c20f53cc (diff) | |
| download | linux-92366810644d5675043c792abb70eaf974a77384.tar.xz | |
rcuscale: Fix smp_processor_id()-in-preemptible warnings
Systems built with CONFIG_DEBUG_PREEMPT=y can trigger the following
BUG while running the rcuscale performance test:
BUG: using smp_processor_id() in preemptible [00000000] code: rcu_scale_write/69
CPU: 0 PID: 66 Comm: rcu_scale_write Not tainted 5.18.0-rc7-next-20220517-yoctodev-standard+
caller is debug_smp_processor_id+0x17/0x20
Call Trace:
<TASK>
dump_stack_lvl+0x49/0x5e
dump_stack+0x10/0x12
check_preemption_disabled+0xdf/0xf0
debug_smp_processor_id+0x17/0x20
rcu_scale_writer+0x2b5/0x580
kthread+0x177/0x1b0
ret_from_fork+0x22/0x30
</TASK>
Reproduction method:
runqemu kvm slirp nographic qemuparams="-m 4096 -smp 8" bootparams="isolcpus=2,3
nohz_full=2,3 rcu_nocbs=2,3 rcutree.dump_tree=1 rcuscale.shutdown=false
rcuscale.gp_async=true" -d
The problem is that the rcu_scale_writer() kthreads fail to set the
PF_NO_SETAFFINITY flags, which causes is_percpu_thread() to assume
that the kthread's affinity might change at any time, thus the BUG
noted above.
This commit therefore causes rcu_scale_writer() to set PF_NO_SETAFFINITY
in its kthread's ->flags field, thus preventing this BUG.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/rcuscale.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c index 277a5bfb37d4..3ef02d4a8108 100644 --- a/kernel/rcu/rcuscale.c +++ b/kernel/rcu/rcuscale.c @@ -419,6 +419,7 @@ rcu_scale_writer(void *arg) VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started"); WARN_ON(!wdpp); set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)); + current->flags |= PF_NO_SETAFFINITY; sched_set_fifo_low(current); if (holdoff) |