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.
This issue was detected by using the Coccinelle software.
v2: Add a function doing the allocations which is called
outside the lock and passing the allocated data to
create_active().
v3: Use the matching deallocators i.e., free_page()
and free_pages(), respectively.
Suggested-by: Juergen Gross <[email protected]>
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 | 71 ++++++++++++++++++++++++++++++-------
1 file changed, 59 insertions(+), 12 deletions(-)
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index 2f11ca72a281..a26f416daf46 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -335,7 +335,43 @@ int pvcalls_front_socket(struct socket *sock)
return ret;
}
-static int create_active(struct sock_mapping *map, int *evtchn)
+struct sock_mapping_active_ring {
+ struct pvcalls_data_intf *ring;
+ RING_IDX ring_order;
+ void *bytes;
+};
+
+static int alloc_active_ring(struct sock_mapping_active_ring *active_ring)
+{
+ active_ring->ring = NULL;
+ active_ring->bytes = NULL;
+
+ active_ring->ring = (struct pvcalls_data_intf *)
+ __get_free_page(GFP_KERNEL | __GFP_ZERO);
+ if (active_ring->ring == NULL)
+ goto out_error;
+ active_ring->ring_order = PVCALLS_RING_ORDER;
+ active_ring->bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+ PVCALLS_RING_ORDER);
+ if (active_ring->bytes == NULL)
+ goto out_error;
+
+ return 0;
+
+out_error:
+ free_pages((unsigned long)active_ring->bytes, active_ring->ring_order);
+ free_page((unsigned long)active_ring->ring);
+ return -ENOMEM;
+}
+
+static void free_active_ring(struct sock_mapping_active_ring *active_ring)
+{
+ free_pages((unsigned long)active_ring->bytes, active_ring->ring_order);
+ free_page((unsigned long)active_ring->ring);
+}
+
+static int create_active(struct sock_mapping *map, int *evtchn,
+ struct sock_mapping_active_ring *active_ring)
{
void *bytes;
int ret = -ENOMEM, irq = -1, i;
@@ -343,15 +379,9 @@ static int create_active(struct sock_mapping *map, int *evtchn)
*evtchn = -1;
init_waitqueue_head(&map->active.inflight_conn_req);
- map->active.ring = (struct pvcalls_data_intf *)
- __get_free_page(GFP_KERNEL | __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,
- PVCALLS_RING_ORDER);
- if (bytes == NULL)
- goto out_error;
+ map->active.ring = active_ring->ring;
+ map->active.ring->ring_order = active_ring->ring_order;
+ bytes = active_ring->bytes;
for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
map->active.ring->ref[i] = gnttab_grant_foreign_access(
pvcalls_front_dev->otherend_id,
@@ -397,6 +427,7 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
struct sock_mapping *map = NULL;
struct xen_pvcalls_request *req;
int notify, req_id, ret, evtchn;
+ struct sock_mapping_active_ring active_ring;
if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
return -EOPNOTSUPP;
@@ -406,15 +437,21 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
return PTR_ERR(map);
bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
+ ret = alloc_active_ring(&active_ring);
+ if (ret < 0) {
+ pvcalls_exit_sock(sock);
+ return ret;
+ }
spin_lock(&bedata->socket_lock);
ret = get_request(bedata, &req_id);
if (ret < 0) {
spin_unlock(&bedata->socket_lock);
+ free_active_ring(&active_ring);
pvcalls_exit_sock(sock);
return ret;
}
- ret = create_active(map, &evtchn);
+ ret = create_active(map, &evtchn, &active_ring);
if (ret < 0) {
spin_unlock(&bedata->socket_lock);
pvcalls_exit_sock(sock);
@@ -744,6 +781,7 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
struct sock_mapping *map2 = NULL;
struct xen_pvcalls_request *req;
int notify, req_id, ret, evtchn, nonblock;
+ struct sock_mapping_active_ring active_ring;
map = pvcalls_enter_sock(sock);
if (IS_ERR(map))
@@ -780,12 +818,20 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
}
}
+ ret = alloc_active_ring(&active_ring);
+ if (ret < 0) {
+ clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
+ (void *)&map->passive.flags);
+ pvcalls_exit_sock(sock);
+ return ret;
+ }
spin_lock(&bedata->socket_lock);
ret = get_request(bedata, &req_id);
if (ret < 0) {
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags);
spin_unlock(&bedata->socket_lock);
+ free_active_ring(&active_ring);
pvcalls_exit_sock(sock);
return ret;
}
@@ -794,10 +840,11 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags);
spin_unlock(&bedata->socket_lock);
+ free_active_ring(&active_ring);
pvcalls_exit_sock(sock);
return -ENOMEM;
}
- ret = create_active(map2, &evtchn);
+ ret = create_active(map2, &evtchn, &active_ring);
if (ret < 0) {
kfree(map2);
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
--
2.19.1
On 30/11/2018 12:01, 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.
>
> This issue was detected by using the Coccinelle software.
>
> v2: Add a function doing the allocations which is called
> outside the lock and passing the allocated data to
> create_active().
> v3: Use the matching deallocators i.e., free_page()
> and free_pages(), respectively.
>
> Suggested-by: Juergen Gross <[email protected]>
> 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]
> ---
This patch is malformed. Please send it via an appropriate tool/mailer.
See e.g. Documentation/process/submitting-patches.rst or
Documentation/process/email-clients.rst in the Linux kernel source tree.
Juergen
On 11/30/18 6:01 AM, 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.
>
> This issue was detected by using the Coccinelle software.
>
> v2: Add a function doing the allocations which is called
> outside the lock and passing the allocated data to
> create_active().
> v3: Use the matching deallocators i.e., free_page()
> and free_pages(), respectively.
>
> Suggested-by: Juergen Gross <[email protected]>
> 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 | 71 ++++++++++++++++++++++++++++++-------
> 1 file changed, 59 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
> index 2f11ca72a281..a26f416daf46 100644
> --- a/drivers/xen/pvcalls-front.c
> +++ b/drivers/xen/pvcalls-front.c
> @@ -335,7 +335,43 @@ int pvcalls_front_socket(struct socket *sock)
> return ret;
> }
>
> -static int create_active(struct sock_mapping *map, int *evtchn)
> +struct sock_mapping_active_ring {
> + struct pvcalls_data_intf *ring;
> + RING_IDX ring_order;
> + void *bytes;
> +};
> +
> +static int alloc_active_ring(struct sock_mapping_active_ring *active_ring)
> +{
> + active_ring->ring = NULL;
This is not necessary.
> + active_ring->bytes = NULL;
> +
> + active_ring->ring = (struct pvcalls_data_intf *)
> + __get_free_page(GFP_KERNEL | __GFP_ZERO);
> + if (active_ring->ring == NULL)
> + goto out_error;
> + active_ring->ring_order = PVCALLS_RING_ORDER;
> + active_ring->bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
> + PVCALLS_RING_ORDER);
> + if (active_ring->bytes == NULL)
> + goto out_error;
> +
> + return 0;
> +
> +out_error:
> + free_pages((unsigned long)active_ring->bytes, active_ring->ring_order);
> + free_page((unsigned long)active_ring->ring);
> + return -ENOMEM;
> +}
> +
> @@ -397,6 +427,7 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
> struct sock_mapping *map = NULL;
> struct xen_pvcalls_request *req;
> int notify, req_id, ret, evtchn;
> + struct sock_mapping_active_ring active_ring;
>
> if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
> return -EOPNOTSUPP;
> @@ -406,15 +437,21 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
> return PTR_ERR(map);
>
> bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
> + ret = alloc_active_ring(&active_ring);
Why not just alloc_active_ring(map)?
-boris
On Fri, 30 Nov 2018, Boris Ostrovsky wrote:
> On 11/30/18 6:01 AM, 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.
> >
> > This issue was detected by using the Coccinelle software.
> >
> > v2: Add a function doing the allocations which is called
> > outside the lock and passing the allocated data to
> > create_active().
> > v3: Use the matching deallocators i.e., free_page()
> > and free_pages(), respectively.
> >
> > Suggested-by: Juergen Gross <[email protected]>
> > 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 | 71 ++++++++++++++++++++++++++++++-------
> > 1 file changed, 59 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
> > index 2f11ca72a281..a26f416daf46 100644
> > --- a/drivers/xen/pvcalls-front.c
> > +++ b/drivers/xen/pvcalls-front.c
> > @@ -335,7 +335,43 @@ int pvcalls_front_socket(struct socket *sock)
> > return ret;
> > }
> >
> > -static int create_active(struct sock_mapping *map, int *evtchn)
> > +struct sock_mapping_active_ring {
> > + struct pvcalls_data_intf *ring;
> > + RING_IDX ring_order;
> > + void *bytes;
> > +};
> > +
> > +static int alloc_active_ring(struct sock_mapping_active_ring *active_ring)
> > +{
> > + active_ring->ring = NULL;
>
> This is not necessary.
>
> > + active_ring->bytes = NULL;
> > +
> > + active_ring->ring = (struct pvcalls_data_intf *)
> > + __get_free_page(GFP_KERNEL | __GFP_ZERO);
> > + if (active_ring->ring == NULL)
> > + goto out_error;
> > + active_ring->ring_order = PVCALLS_RING_ORDER;
> > + active_ring->bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
> > + PVCALLS_RING_ORDER);
> > + if (active_ring->bytes == NULL)
> > + goto out_error;
> > +
> > + return 0;
> > +
> > +out_error:
> > + free_pages((unsigned long)active_ring->bytes, active_ring->ring_order);
> > + free_page((unsigned long)active_ring->ring);
> > + return -ENOMEM;
> > +}
> > +
>
>
>
> > @@ -397,6 +427,7 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
> > struct sock_mapping *map = NULL;
> > struct xen_pvcalls_request *req;
> > int notify, req_id, ret, evtchn;
> > + struct sock_mapping_active_ring active_ring;
> >
> > if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
> > return -EOPNOTSUPP;
> > @@ -406,15 +437,21 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
> > return PTR_ERR(map);
> >
> > bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
> > + ret = alloc_active_ring(&active_ring);
>
> Why not just alloc_active_ring(map)?
Yes, I think it would be better to pre-populate map (struct
sock_mapping), rather than introducing one more new struct (struct
sock_mapping_active_ring).