On 11/03/2017 07:25 PM, Tetsuo Handa wrote:
Wei Wang wrote:
@@ -164,6 +284,8 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
break;
}
+ if (use_sg && xb_set_page(vb, page, &pfn_min, &pfn_max) < 0)
Isn't this leaking "page" ?
Right, thanks, will add __free_page(page) here.
@@ -184,8 +307,12 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
num_allocated_pages = vb->num_pfns;
/* Did we get any? */
- if (vb->num_pfns != 0)
- tell_host(vb, vb->inflate_vq);
+ if (vb->num_pfns) {
+ if (use_sg)
+ tell_host_sgs(vb, vb->inflate_vq, pfn_min, pfn_max);
Please describe why tell_host_sgs() can work without __GFP_DIRECT_RECLAIM allocation,
for tell_host_sgs() is called with vb->balloon_lock mutex held.
Essentially,
tell_host_sgs()-->send_balloon_page_sg()-->add_one_sg()-->virtqueue_add_inbuf(
, , num=1 ,,GFP_KERNEL)
won't need any memory allocation, because we always add one sg (i.e.
num=1) each time. That memory
allocation option is only used when multiple sgs are added (i.e. num >
1) and the implementation inside virtqueue_add_inbuf
need allocation of indirect descriptor table.
We could also add some comments above the function to explain a little
about this if necessary.
@@ -223,7 +353,13 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
page = balloon_page_dequeue(vb_dev_info);
if (!page)
break;
- set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
+ if (use_sg) {
+ if (xb_set_page(vb, page, &pfn_min, &pfn_max) < 0)
Isn't this leaking "page" ?
Yes, will make it:
if (xb_set_page(vb, page, &pfn_min, &pfn_max) < 0) {
balloon_page_enqueue(..., page);
break;
}
If this is inside vb->balloon_lock mutex (isn't this?), xb_set_page() must not
use __GFP_DIRECT_RECLAIM allocation, for leak_balloon_sg_oom() will be blocked
on vb->balloon_lock mutex.
OK. Since the preload() doesn't need too much memory (< 4K in total),
how about GFP_NOWAIT here?
Best,
Wei
