From: Steven Rostedt <[email protected]>
The ret_stack_list is an array of ret_stack shadow stacks for the function
graph usage. When the first function graph is enabled, all tasks in the
system get a shadow stack. The ret_stack_list is a 32 element array of
pointers to these shadow stacks. It allocates the shadow stack in batches
(32 stacks at a time), assigns them to running tasks, and continues until
all tasks are covered.
When the function graph shadow stack changed from an array of
ftrace_ret_stack structures to an array of longs, the allocation of
ret_stack_list went from allocating an array of 32 elements to just a
block defined by SHADOW_STACK_SIZE. Luckily, that's defined as PAGE_SIZE
and is much more than enough to hold 32 pointers. But it is way overkill
for the amount needed to allocate.
Change the allocation of ret_stack_list back to a kcalloc() of
FTRACE_RETSTACK_ALLOC_SIZE pointers.
Fixes: 42675b723b484 ("function_graph: Convert ret_stack to a series of longs")
Signed-off-by: Steven Rostedt (Google) <[email protected]>
---
kernel/trace/fgraph.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 43f4e3f57438..41e7a15dcb50 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -1162,7 +1162,8 @@ static int start_graph_tracing(void)
unsigned long **ret_stack_list;
int ret;
- ret_stack_list = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL);
+ ret_stack_list = kcalloc(FTRACE_RETSTACK_ALLOC_SIZE,
+ sizeof(*ret_stack_list), GFP_KERNEL);
if (!ret_stack_list)
return -ENOMEM;
--
2.45.2
