In preporation for dynamic kernel stacks do not zero the whole span of
the stack, but instead only the pages that are part of the vm_area.
This is because with dynamic stacks we might have only partially
populated stacks.
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
---
kernel/fork.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index 6a2f2c85e09f..41e0baee79d2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -263,8 +263,8 @@ static int memcg_charge_kernel_stack(struct vm_struct *vm)
static int alloc_thread_stack_node(struct task_struct *tsk, int node)
{
struct vm_struct *vm_area;
+ int i, j, nr_pages;
void *stack;
- int i;
for (i = 0; i < NR_CACHED_STACKS; i++) {
vm_area = this_cpu_xchg(cached_stacks[i], NULL);
@@ -282,7 +282,9 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
stack = kasan_reset_tag(vm_area->addr);
/* Clear stale pointers from reused stack. */
- memset(stack, 0, THREAD_SIZE);
+ nr_pages = vm_area->nr_pages;
+ for (j = 0; j < nr_pages; j++)
+ clear_page(page_address(vm_area->pages[j]));
tsk->stack_vm_area = vm_area;
tsk->stack = stack;
--
2.44.0.278.ge034bb2e1d-goog
