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fork: Don't assign the stack pointer in dup_task_struct()

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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@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20220217102406.3697941-5-bigeasy@linutronix.de
This commit is contained in:
Sebastian Andrzej Siewior 2022-02-17 11:24:02 +01:00 committed by Thomas Gleixner
parent 2bb0529c0b
commit 7865aba3ad
1 changed files with 16 additions and 31 deletions
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47
kernel/fork.c
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@ -211,7 +211,7 @@ static int free_vm_stack_cache(unsigned int cpu)
return 0; 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; void *stack;
int i; int i;
@ -232,7 +232,7 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
tsk->stack_vm_area = s; tsk->stack_vm_area = s;
tsk->stack = s->addr; tsk->stack = s->addr;
return s->addr; return 0;
} }
/* /*
@ -245,17 +245,16 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
THREADINFO_GFP & ~__GFP_ACCOUNT, THREADINFO_GFP & ~__GFP_ACCOUNT,
PAGE_KERNEL, PAGE_KERNEL,
0, node, __builtin_return_address(0)); 0, node, __builtin_return_address(0));
if (!stack)
return -ENOMEM;
/* /*
* We can't call find_vm_area() in interrupt context, and * We can't call find_vm_area() in interrupt context, and
* free_thread_stack() can be called in interrupt context, * free_thread_stack() can be called in interrupt context,
* so cache the vm_struct. * so cache the vm_struct.
*/ */
if (stack) { tsk->stack_vm_area = find_vm_area(stack);
tsk->stack_vm_area = find_vm_area(stack); tsk->stack = stack;
tsk->stack = stack; return 0;
}
return stack;
} }
static void free_thread_stack(struct task_struct *tsk) static void free_thread_stack(struct task_struct *tsk)
@ -282,16 +281,16 @@ static void free_thread_stack(struct task_struct *tsk)
# else /* !CONFIG_VMAP_STACK */ # 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, struct page *page = alloc_pages_node(node, THREADINFO_GFP,
THREAD_SIZE_ORDER); THREAD_SIZE_ORDER);
if (likely(page)) { if (likely(page)) {
tsk->stack = kasan_reset_tag(page_address(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) static void free_thread_stack(struct task_struct *tsk)
@ -305,14 +304,13 @@ static void free_thread_stack(struct task_struct *tsk)
static struct kmem_cache *thread_stack_cache; static struct kmem_cache *thread_stack_cache;
static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, static int alloc_thread_stack_node(struct task_struct *tsk, int node)
int node)
{ {
unsigned long *stack; unsigned long *stack;
stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node); stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
stack = kasan_reset_tag(stack); stack = kasan_reset_tag(stack);
tsk->stack = stack; tsk->stack = stack;
return stack; return stack ? 0 : -ENOMEM;
} }
static void free_thread_stack(struct task_struct *tsk) static void free_thread_stack(struct task_struct *tsk)
@ -332,13 +330,13 @@ void thread_stack_cache_init(void)
# endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */ # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
#else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */ #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; unsigned long *stack;
stack = arch_alloc_thread_stack_node(tsk, node); stack = arch_alloc_thread_stack_node(tsk, node);
tsk->stack = stack; tsk->stack = stack;
return stack; return stack ? 0 : -ENOMEM;
} }
static void free_thread_stack(struct task_struct *tsk) static void free_thread_stack(struct task_struct *tsk)
@ -895,8 +893,6 @@ void set_task_stack_end_magic(struct task_struct *tsk)
static struct task_struct *dup_task_struct(struct task_struct *orig, int node) static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
{ {
struct task_struct *tsk; struct task_struct *tsk;
unsigned long *stack;
struct vm_struct *stack_vm_area __maybe_unused;
int err; int err;
if (node == NUMA_NO_NODE) if (node == NUMA_NO_NODE)
@ -909,24 +905,13 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
if (err) if (err)
goto free_tsk; goto free_tsk;
stack = alloc_thread_stack_node(tsk, node); err = alloc_thread_stack_node(tsk, node);
if (!stack) if (err)
goto free_tsk; goto free_tsk;
if (memcg_charge_kernel_stack(tsk)) if (memcg_charge_kernel_stack(tsk))
goto free_stack; 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 #ifdef CONFIG_THREAD_INFO_IN_TASK
refcount_set(&tsk->stack_refcount, 1); refcount_set(&tsk->stack_refcount, 1);
#endif #endif