From: Fenghua Yu <[email protected]> intel_rdt_sched_in() calls this_cpu_ptr() read and write pqr_state and update PQR_ASSOC on current cpu. If execution of the function is preempted and switched to another CPU, the results are wrong. If CONFIG_DEBUG_PREEMPT is turned on, the issue is reported as "BUG: smp_processor_id() running in preemptible code." when moving a task to a rdtgroup in move_myself().
Disable preempt before intel_rdt_sched_in() and eanble preempt after the function in move_myself() to solve the issue. Signed-off-by: Fenghua Yu <[email protected]> --- arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h index 6e90e87..eaaa765 100644 --- a/arch/x86/include/asm/intel_rdt.h +++ b/arch/x86/include/asm/intel_rdt.h @@ -192,6 +192,9 @@ int rdtgroup_schemata_show(struct kernfs_open_file *of, * resctrl file system. * - Caches the per cpu CLOSid values and does the MSR write only * when a task with a different CLOSid is scheduled in. + * - Caller needs to disable preempt before calling this function. + * The function doesn't check preemptible. Scheduler hot path + * disables preempt already. */ static inline void intel_rdt_sched_in(void) { diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c index fb8e03e..9c6f732 100644 --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -326,8 +326,10 @@ static void move_myself(struct callback_head *head) kfree(rdtgrp); } + get_cpu(); /* update PQR_ASSOC MSR to make resource group go into effect */ intel_rdt_sched_in(); + put_cpu(); kfree(callback); }
