On Fri, 18 Oct 2024 21:52:12 -0400 Steven Rostedt <[email protected]> wrote:
> 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. Looks good to me. Acked-by: Masami Hiramatsu (Google) <[email protected]> Thanks, > > 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 > -- Masami Hiramatsu (Google) <[email protected]>
