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Since tracepoints use RCU for protection, they must not be called on offline cpus. trace_mm_page_free can be called on an offline cpu in this scenario caught by LOCKDEP: =============================== [ INFO: suspicious RCU usage. ] 4.1.0-rc1+ #9 Not tainted ------------------------------- include/trace/events/kmem.h:170 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.1.0-rc1+ #9 Call Trace: .dump_stack+0x98/0xd4 (unreliable) .lockdep_rcu_suspicious+0x108/0x170 .free_pages_prepare+0x494/0x680 .free_hot_cold_page+0x50/0x280 .destroy_context+0x90/0xd0 .__mmdrop+0x58/0x160 .idle_task_exit+0xf0/0x100 .pnv_smp_cpu_kill_self+0x58/0x2c0 .cpu_die+0x34/0x50 .arch_cpu_idle_dead+0x20/0x40 .cpu_startup_entry+0x708/0x7a0 .start_secondary+0x36c/0x3a0 start_secondary_prolog+0x10/0x14 Fix this by converting mm_page_free trace point into TRACE_EVENT_CONDITION where condition is cpu_online(smp_processor_id()) Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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events | ||
define_trace.h | ||
ftrace.h | ||
syscall.h |