Commit 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the bitmap like
events do") added a couple of this_cpu_read calls to the ftrace code.
On x86 this is not a problem, since it has single instructions to read
percpu data. Other architectures which use the generic variant now
have additional preempt_disable and preempt_enable calls in the core
ftrace code. This may lead to recursive calls and in result to a dead
machine, e.g. if preemption and debugging options are enabled.
To fix this use the notrace variant of preempt_disable and
preempt_enable within the generic percpu code.
Reported-and-bisected-by: Sebastian Ott <seb...@linux.vnet.ibm.com>
Tested-by: Sebastian Ott <seb...@linux.vnet.ibm.com>
Fixes: 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the bitmap like events
do")
Signed-off-by: Heiko Carstens <heiko.carst...@de.ibm.com>
---
include/asm-generic/percpu.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 40e887068da2..0504ef8f3aa3 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -118,9 +118,9 @@ do {
\
#define this_cpu_generic_read(pcp) \
({ \
typeof(pcp) __ret; \
- preempt_disable(); \
+ preempt_disable_notrace(); \
__ret = raw_cpu_generic_read(pcp); \
- preempt_enable(); \
+ preempt_enable_notrace(); \
__ret; \
})
--
2.8.4
