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Message-Id: <20211118143452.136421-5-bigeasy@linutronix.de>
Date: Thu, 18 Nov 2021 15:34:48 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org
Cc: Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Andy Lutomirski <luto@...nel.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 4/8] kernel/fork: Don't assign the stack pointer in dup_task_struct().
All four versions of alloc_thread_stack_node() assign now
task_struct::stack in case the allocation was successful.
Let alloc_thread_stack_node() return an error code instead of the stack
pointer and remove the stack assignment in dup_task_struct().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
kernel/fork.c | 47 ++++++++++++++++-------------------------------
1 file changed, 16 insertions(+), 31 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index d1681a415cdf1..5e58e0a923f85 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -210,7 +210,7 @@ static int free_vm_stack_cache(unsigned int cpu)
return 0;
}
-static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
{
void *stack;
int i;
@@ -231,7 +231,7 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
tsk->stack_vm_area = s;
tsk->stack = s->addr;
- return s->addr;
+ return 0;
}
/*
@@ -244,17 +244,16 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
THREADINFO_GFP & ~__GFP_ACCOUNT,
PAGE_KERNEL,
0, node, __builtin_return_address(0));
-
+ if (!stack)
+ return -ENOMEM;
/*
* We can't call find_vm_area() in interrupt context, and
* free_thread_stack() can be called in interrupt context,
* so cache the vm_struct.
*/
- if (stack) {
- tsk->stack_vm_area = find_vm_area(stack);
- tsk->stack = stack;
- }
- return stack;
+ tsk->stack_vm_area = find_vm_area(stack);
+ tsk->stack = stack;
+ return 0;
}
static void free_thread_stack(struct task_struct *tsk)
@@ -281,16 +280,16 @@ static void free_thread_stack(struct task_struct *tsk)
# else /* !CONFIG_VMAP_STACK */
-static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
{
struct page *page = alloc_pages_node(node, THREADINFO_GFP,
THREAD_SIZE_ORDER);
if (likely(page)) {
tsk->stack = kasan_reset_tag(page_address(page));
- return tsk->stack;
+ return 0;
}
- return NULL;
+ return -ENOMEM;
}
static void free_thread_stack(struct task_struct *tsk)
@@ -304,14 +303,13 @@ static void free_thread_stack(struct task_struct *tsk)
static struct kmem_cache *thread_stack_cache;
-static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
- int node)
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
{
unsigned long *stack;
stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
stack = kasan_reset_tag(stack);
tsk->stack = stack;
- return stack;
+ return stack ? 0 : -ENOMEM;
}
static void free_thread_stack(struct task_struct *tsk)
@@ -331,13 +329,13 @@ void thread_stack_cache_init(void)
# endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
#else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
-static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
{
unsigned long *stack;
stack = arch_alloc_thread_stack_node(tsk, node);
tsk->stack = stack;
- return stack;
+ return stack ? 0 : -ENOMEM;
}
static void free_thread_stack(struct task_struct *tsk, bool cache_only)
@@ -893,8 +891,6 @@ void set_task_stack_end_magic(struct task_struct *tsk)
static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
{
struct task_struct *tsk;
- unsigned long *stack;
- struct vm_struct *stack_vm_area __maybe_unused;
int err;
if (node == NUMA_NO_NODE)
@@ -907,24 +903,13 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
if (err)
goto free_tsk;
- stack = alloc_thread_stack_node(tsk, node);
- if (!stack)
+ err = alloc_thread_stack_node(tsk, node);
+ if (err)
goto free_tsk;
if (memcg_charge_kernel_stack(tsk))
goto free_stack;
- stack_vm_area = task_stack_vm_area(tsk);
-
- /*
- * arch_dup_task_struct() clobbers the stack-related fields. Make
- * sure they're properly initialized before using any stack-related
- * functions again.
- */
- tsk->stack = stack;
-#ifdef CONFIG_VMAP_STACK
- tsk->stack_vm_area = stack_vm_area;
-#endif
#ifdef CONFIG_THREAD_INFO_IN_TASK
refcount_set(&tsk->stack_refcount, 1);
#endif
--
2.33.1
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