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Subject[tip: core/core] fork: Move memcg_charge_kernel_stack() into CONFIG_VMAP_STACK
The following commit has been merged into the core/core branch of tip:

Commit-ID: f1c1a9ee00e4c53c9ccc03ec1aff4792948a25eb
Gitweb: https://git.kernel.org/tip/f1c1a9ee00e4c53c9ccc03ec1aff4792948a25eb
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Thu, 17 Feb 2022 11:24:03 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 22 Feb 2022 22:25:01 +01:00

fork: Move memcg_charge_kernel_stack() into CONFIG_VMAP_STACK

memcg_charge_kernel_stack() is only used in the CONFIG_VMAP_STACK case.

Move memcg_charge_kernel_stack() into the CONFIG_VMAP_STACK block and
invoke it from within alloc_thread_stack_node().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20220217102406.3697941-6-bigeasy@linutronix.de

---
kernel/fork.c | 69 ++++++++++++++++++++++++++------------------------
1 file changed, 36 insertions(+), 33 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 875bd43..ac63e7f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -211,6 +211,32 @@ static int free_vm_stack_cache(unsigned int cpu)
return 0;
}

+static int memcg_charge_kernel_stack(struct task_struct *tsk)
+{
+ struct vm_struct *vm = task_stack_vm_area(tsk);
+ int i;
+ int ret;
+
+ BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
+ BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
+
+ for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
+ ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
+ if (ret)
+ goto err;
+ }
+ return 0;
+err:
+ /*
+ * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
+ * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
+ * ignore this page.
+ */
+ for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
+ memcg_kmem_uncharge_page(vm->pages[i], 0);
+ return ret;
+}
+
static int alloc_thread_stack_node(struct task_struct *tsk, int node)
{
void *stack;
@@ -230,6 +256,11 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
/* Clear stale pointers from reused stack. */
memset(s->addr, 0, THREAD_SIZE);

+ if (memcg_charge_kernel_stack(tsk)) {
+ vfree(s->addr);
+ return -ENOMEM;
+ }
+
tsk->stack_vm_area = s;
tsk->stack = s->addr;
return 0;
@@ -247,6 +278,11 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
0, node, __builtin_return_address(0));
if (!stack)
return -ENOMEM;
+
+ if (memcg_charge_kernel_stack(tsk)) {
+ vfree(stack);
+ return -ENOMEM;
+ }
/*
* We can't call find_vm_area() in interrupt context, and
* free_thread_stack() can be called in interrupt context,
@@ -418,36 +454,6 @@ static void account_kernel_stack(struct task_struct *tsk, int account)
}
}

-static int memcg_charge_kernel_stack(struct task_struct *tsk)
-{
-#ifdef CONFIG_VMAP_STACK
- struct vm_struct *vm = task_stack_vm_area(tsk);
- int ret;
-
- BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
-
- if (vm) {
- int i;
-
- BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
-
- for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
- /*
- * If memcg_kmem_charge_page() fails, page's
- * memory cgroup pointer is NULL, and
- * memcg_kmem_uncharge_page() in free_thread_stack()
- * will ignore this page.
- */
- ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL,
- 0);
- if (ret)
- return ret;
- }
- }
-#endif
- return 0;
-}
-
static void release_task_stack(struct task_struct *tsk)
{
if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
@@ -909,9 +915,6 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
if (err)
goto free_tsk;

- if (memcg_charge_kernel_stack(tsk))
- goto free_stack;
-
#ifdef CONFIG_THREAD_INFO_IN_TASK
refcount_set(&tsk->stack_refcount, 1);
#endif
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