The following commit has been merged into the core/core branch of tip: Commit-ID: 7865aba3ade4cf30f0ac08e015550084a50d9afb Gitweb: https://git.kernel.org/tip/7865aba3ade4cf30f0ac08e015550084a50d9afb Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> AuthorDate: Thu, 17 Feb 2022 11:24:02 +01:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Tue, 22 Feb 2022 22:25:01 +01:00 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@xxxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Acked-by: Andy Lutomirski <luto@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220217102406.3697941-5-bigeasy@xxxxxxxxxxxxx --- kernel/fork.c | 47 ++++++++++++++++------------------------------- 1 file changed, 16 insertions(+), 31 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index 7b70c47..875bd43 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -211,7 +211,7 @@ 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; @@ -232,7 +232,7 @@ 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; } /* @@ -245,17 +245,16 @@ 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) @@ -282,16 +281,16 @@ 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) @@ -305,14 +304,13 @@ 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) @@ -332,13 +330,13 @@ 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) @@ -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) { struct task_struct *tsk; - unsigned long *stack; - struct vm_struct *stack_vm_area __maybe_unused; int err; if (node == NUMA_NO_NODE) @@ -909,24 +905,13 @@ 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
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