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.pi...@linaro.org>
Cc: Will Deacon <will.dea...@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) &&
--
1.8.1.2
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