Commit 64960497 authored by Pasha Tatashin's avatar Pasha Tatashin Committed by Andrew Morton
Browse files

fork: clean up ifdef logic around stack allocation 

There is an unneeded OR in the ifdef functions that are used to allocate
and free kernel stacks based on direct map or vmap.  Adding dynamic stack
support would complicate this logic even further.

Therefore, clean up by changing the order so OR is no longer needed.

Link: https://lkml.kernel.org/r/20250618-fork-fixes-v4-1-2e05a2e1f5fc@linaro.org


Signed-off-by: default avatarPasha Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/20240311164638.2015063-3-pasha.tatashin@soleen.com


Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 816a8800

kernel/fork.c

+11 −11
Original line number Diff line number Diff line
@@ -188,12 +188,6 @@ static inline void free_task_struct(struct task_struct *tsk) 
	kmem_cache_free(task_struct_cachep, tsk);

}



/*

 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a

 * kmemcache based allocator.

 */

# if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)



#ifdef CONFIG_VMAP_STACK

/*

 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
@@ -346,6 +340,12 @@ static void free_thread_stack(struct task_struct *tsk) 


#else /* !CONFIG_VMAP_STACK */



/*

 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a

 * kmemcache based allocator.

 */

#if THREAD_SIZE >= PAGE_SIZE



static void thread_stack_free_rcu(struct rcu_head *rh)

{

	__free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
@@ -376,8 +376,7 @@ static void free_thread_stack(struct task_struct *tsk) 
	tsk->stack = NULL;

}



#  endif /* CONFIG_VMAP_STACK */

# else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */

#else /* !(THREAD_SIZE >= PAGE_SIZE) */



static struct kmem_cache *thread_stack_cache;
@@ -416,7 +415,8 @@ void thread_stack_cache_init(void) 
	BUG_ON(thread_stack_cache == NULL);

}



# endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */

#endif /* THREAD_SIZE >= PAGE_SIZE */

#endif /* CONFIG_VMAP_STACK */



/* SLAB cache for signal_struct structures (tsk->signal) */

static struct kmem_cache *signal_cachep;