forked from Minki/linux
9236681064
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> |
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| .. | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||
| rcu_segcblist.c | ||
| rcu_segcblist.h | ||
| rcu.h | ||
| rcuscale.c | ||
| rcutorture.c | ||
| refscale.c | ||
| srcutiny.c | ||
| srcutree.c | ||
| sync.c | ||
| tasks.h | ||
| tiny.c | ||
| tree_exp.h | ||
| tree_nocb.h | ||
| tree_plugin.h | ||
| tree_stall.h | ||
| tree.c | ||
| tree.h | ||
| update.c | ||