On Wed, Oct 19, 2016 at 08:34:40AM -0700, Andy Lutomirski wrote:
>
> It would be quite awkward for a task stack to get freed from a
> sleepable context, because the obvious sleepable context is the task
> itself, and it still needs its stack. This was true even in the old
> regime when task stacks were freed from RCU context.
>
> But vfree has a magic automatic deferral mechanism. Couldn't you make
> the non-deferred case might_sleep()?
But it's only magic from interrupt context..
Chris, does this patch make virtually mapped stack work for you again?
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f2481cb..942e02d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1533,7 +1533,7 @@ void vfree(const void *addr)
if (!addr)
return;
- if (unlikely(in_interrupt())) {
+ if (in_interrupt() || in_atomic()) {
struct vfree_deferred *p = this_cpu_ptr(&vfree_deferred);
if (llist_add((struct llist_node *)addr, &p->list))
schedule_work(&p->wq);
--
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