This is a note to let you know that I've just added the patch titled
fgraph: Allocate ret_stack_list with proper size
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fgraph-allocate-ret_stack_list-with-proper-size.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 16e9fc4fe3e673aaf95a9d0fb5832c0306c4a4dc
Author: Steven Rostedt <rostedt@xxxxxxxxxxx>
Date: Fri Oct 18 21:52:12 2024 -0400
fgraph: Allocate ret_stack_list with proper size
[ Upstream commit fae4078c289a2f24229c0de652249948b1cd6bdb ]
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.
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Link: https://lore.kernel.org/20241018215212.23f13f40@rorschach
Fixes: 42675b723b484 ("function_graph: Convert ret_stack to a series of longs")
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 43f4e3f57438b..41e7a15dcb50c 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;
