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'
Signed-off-by: Jean Pihet jean.pihet@linaro.org Cc: Will Deacon will.deacon@arm.com --- 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 4238bcb..6493c4c 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) &&