The problem is that we call this with a spin lock held.
The call tree is:
pvcalls_front_accept() holds bedata->socket_lock.
-> create_active()
-> __get_free_pages() uses GFP_KERNEL
The create_active() function is only called from pvcalls_front_accept()
with a spin_lock held, The allocation is not allowed to sleep and
GFP_KERNEL is not sufficient, it has to be ATOMIC.
This issue was detected by using the Coccinelle software.
Signed-off-by: Wen Yang <[email protected]>
CC: Julia Lawall <[email protected]>
CC: Boris Ostrovsky <[email protected]>
CC: Juergen Gross <[email protected]>
CC: Stefano Stabellini <[email protected]>
CC: [email protected]
CC: [email protected]
---
drivers/xen/pvcalls-front.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index 2f11ca72a281..f2bbc06a0f7f 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -344,11 +344,11 @@ static int create_active(struct sock_mapping *map, int *evtchn)
init_waitqueue_head(&map->active.inflight_conn_req);
map->active.ring = (struct pvcalls_data_intf *)
- __get_free_page(GFP_KERNEL | __GFP_ZERO);
+ __get_free_page(GFP_ATOMIC | __GFP_ZERO);
if (map->active.ring == NULL)
goto out_error;
map->active.ring->ring_order = PVCALLS_RING_ORDER;
- bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+ bytes = (void *)__get_free_pages(GFP_ATOMIC | __GFP_ZERO,
PVCALLS_RING_ORDER);
if (bytes == NULL)
goto out_error;
--
2.19.1
On 29/11/2018 13:01, Wen Yang wrote:
> The problem is that we call this with a spin lock held.
> The call tree is:
> pvcalls_front_accept() holds bedata->socket_lock.
> -> create_active()
> -> __get_free_pages() uses GFP_KERNEL
>
> The create_active() function is only called from pvcalls_front_accept()
> with a spin_lock held, The allocation is not allowed to sleep and
> GFP_KERNEL is not sufficient, it has to be ATOMIC.
I'd rather have a function doing the allocations which is called
outside the lock and either passing the allocated data to
create_active() or hook it into map in the allocation function.
Juergen