From a7cc91001e36a4a4152c3ada6c8fe38adc5badbc Mon Sep 17 00:00:00 2001 From: Jean Pihet Date: Mon, 7 Jul 2014 14:45:08 +0100 Subject: [PATCH] ARM: perf: Check that current->mm is alive before getting user callchain An event may occur when an mm is already released. As per commit 20afc60f892d285fde179ead4b24e6a7938c2f1b 'x86, perf: Check that current->mm is alive before getting user callchain' Acked-by: Will Deacon Signed-off-by: Jean Pihet Signed-off-by: Will Deacon --- arch/arm/kernel/perf_event.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c index 4238bcba9d60..6493c4c97d48 100644 --- a/arch/arm/kernel/perf_event.c +++ b/arch/arm/kernel/perf_event.c @@ -590,6 +590,10 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) } perf_callchain_store(entry, regs->ARM_pc); + + if (!current->mm) + return; + tail = (struct frame_tail __user *)regs->ARM_fp - 1; while ((entry->nr < PERF_MAX_STACK_DEPTH) && -- 2.20.1