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kernel/fork.c: virtually mapped stacks: do not disable interrupts

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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: Christoph Lameter <cl@linux.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Lameter 2017-07-12 14:33:11 -07:00 committed by Linus Torvalds
parent 91a90140f9
commit 112166f88c
1 changed files with 5 additions and 11 deletions
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16
kernel/fork.c
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@ -205,19 +205,17 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
void *stack; void *stack;
int i; int i;
local_irq_disable();
for (i = 0; i < NR_CACHED_STACKS; i++) { 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) if (!s)
continue; continue;
this_cpu_write(cached_stacks[i], NULL);
tsk->stack_vm_area = s; tsk->stack_vm_area = s;
local_irq_enable();
return s->addr; return s->addr;
} }
local_irq_enable();
stack = __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE, stack = __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE,
VMALLOC_START, VMALLOC_END, VMALLOC_START, VMALLOC_END,
@ -245,19 +243,15 @@ static inline void free_thread_stack(struct task_struct *tsk)
{ {
#ifdef CONFIG_VMAP_STACK #ifdef CONFIG_VMAP_STACK
if (task_stack_vm_area(tsk)) { if (task_stack_vm_area(tsk)) {
unsigned long flags;
int i; int i;
local_irq_save(flags);
for (i = 0; i < NR_CACHED_STACKS; i++) { 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; continue;
this_cpu_write(cached_stacks[i], tsk->stack_vm_area);
local_irq_restore(flags);
return; return;
} }
local_irq_restore(flags);
vfree_atomic(tsk->stack); vfree_atomic(tsk->stack);
return; return;