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Commit 112166f8 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
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kernel/fork.c: virtually mapped stacks: do not disable interrupts 

The reason to disable interrupts seems to be to avoid switching to a
different processor while handling per cpu data using individual loads and
stores.  If we use per cpu RMV primitives we will not have to disable
interrupts.

Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1705171055130.5898@east.gentwo.org


Signed-off-by: default avatarChristoph Lameter <cl@linux.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 91a90140

kernel/fork.c

+5 −11
Original line number Diff line number Diff line
@@ -205,19 +205,17 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) 
	void *stack;

	int i;



	local_irq_disable();

	for (i = 0; i < NR_CACHED_STACKS; i++) {

		struct vm_struct *s = this_cpu_read(cached_stacks[i]);

		struct vm_struct *s;



		s = this_cpu_xchg(cached_stacks[i], NULL);



		if (!s)

			continue;

		this_cpu_write(cached_stacks[i], NULL);



		tsk->stack_vm_area = s;

		local_irq_enable();

		return s->addr;

	}

	local_irq_enable();



	stack = __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE,

				     VMALLOC_START, VMALLOC_END,
@@ -245,19 +243,15 @@ static inline void free_thread_stack(struct task_struct *tsk) 
{

#ifdef CONFIG_VMAP_STACK

	if (task_stack_vm_area(tsk)) {

		unsigned long flags;

		int i;



		local_irq_save(flags);

		for (i = 0; i < NR_CACHED_STACKS; i++) {

			if (this_cpu_read(cached_stacks[i]))

			if (this_cpu_cmpxchg(cached_stacks[i],

					NULL, tsk->stack_vm_area) != NULL)

				continue;



			this_cpu_write(cached_stacks[i], tsk->stack_vm_area);

			local_irq_restore(flags);

			return;

		}

		local_irq_restore(flags);



		vfree_atomic(tsk->stack);

		return;