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| author | Christoph Lameter <cl@linux.com> | 2017-07-12 14:33:11 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-07-27 15:10:23 -0700 |
| commit | 054728d3bbe4a3047e91a4ff4f66298c4baf6462 (patch) | |
| tree | fc111de1b0e1dc07a185074001590810fc135ab9 | |
| parent | 2541b3c861bc58ac4e01edfa4bb035421ff23501 (diff) | |
| download | linux-stable-054728d3bbe4a3047e91a4ff4f66298c4baf6462.tar.gz linux-stable-054728d3bbe4a3047e91a4ff4f66298c4baf6462.tar.bz2 linux-stable-054728d3bbe4a3047e91a4ff4f66298c4baf6462.zip | |
kernel/fork.c: virtually mapped stacks: do not disable interrupts
commit 112166f88cf83dd11486cf1818672d42b540865b upstream.
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>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/fork.c | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index d927ec11aa7a..6440e0b70cad 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -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; |