* [PATCH, RESEND] xen: allocate gntdev_copy_batch dynamically
@ 2016-02-25 21:25 Arnd Bergmann
2016-02-26 13:44 ` Boris Ostrovsky
0 siblings, 1 reply; 2+ messages in thread
From: Arnd Bergmann @ 2016-02-25 21:25 UTC (permalink / raw)
To: Konrad Rzeszutek Wilk, Boris Ostrovsky, David Vrabel
Cc: linux-arm-kernel, Arnd Bergmann, xen-devel, linux-kernel
struct gntdev_copy_batch is arguably too large to fit on the kernel stack,
and we get a warning about the stack usage in gntdev_ioctl_grant_copy:
drivers/xen/gntdev.c:949:1: error: the frame size of 1240 bytes is larger than 1024 bytes
This changes the code to us a dynamic allocation instead.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: a4cdb556cae0 ("xen/gntdev: add ioctl for grant copy")
---
drivers/xen/gntdev.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
I sent this in January, Boris sent an almost identical patch
as http://www.gossamer-threads.com/lists/xen/devel/414056
but the bug remains present in mainline and linux-next as of
Feb 25.
Could you apply one of the patches before the bug makes it
into v4.5?
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index dc495383ad73..cc753b3a7154 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -915,15 +915,16 @@ static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
{
struct ioctl_gntdev_grant_copy copy;
- struct gntdev_copy_batch batch;
+ struct gntdev_copy_batch *batch;
unsigned int i;
int ret = 0;
if (copy_from_user(©, u, sizeof(copy)))
return -EFAULT;
- batch.nr_ops = 0;
- batch.nr_pages = 0;
+ batch = kzalloc(sizeof(*batch), GFP_KERNEL);
+ if (!batch)
+ return -ENOMEM;
for (i = 0; i < copy.count; i++) {
struct gntdev_grant_copy_segment seg;
@@ -933,18 +934,20 @@ static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
goto out;
}
- ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status);
+ ret = gntdev_grant_copy_seg(batch, &seg, ©.segments[i].status);
if (ret < 0)
goto out;
cond_resched();
}
- if (batch.nr_ops)
- ret = gntdev_copy(&batch);
+ if (batch->nr_ops)
+ ret = gntdev_copy(batch);
+ kfree(batch);
return ret;
out:
- gntdev_put_pages(&batch);
+ gntdev_put_pages(batch);
+ kfree(batch);
return ret;
}
--
2.7.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH, RESEND] xen: allocate gntdev_copy_batch dynamically
2016-02-25 21:25 [PATCH, RESEND] xen: allocate gntdev_copy_batch dynamically Arnd Bergmann
@ 2016-02-26 13:44 ` Boris Ostrovsky
0 siblings, 0 replies; 2+ messages in thread
From: Boris Ostrovsky @ 2016-02-26 13:44 UTC (permalink / raw)
To: Arnd Bergmann, Konrad Rzeszutek Wilk, David Vrabel
Cc: linux-arm-kernel, xen-devel, linux-kernel
On 02/25/2016 04:25 PM, Arnd Bergmann wrote:
> struct gntdev_copy_batch is arguably too large to fit on the kernel stack,
> and we get a warning about the stack usage in gntdev_ioctl_grant_copy:
>
> drivers/xen/gntdev.c:949:1: error: the frame size of 1240 bytes is larger than 1024 bytes
>
> This changes the code to us a dynamic allocation instead.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Fixes: a4cdb556cae0 ("xen/gntdev: add ioctl for grant copy")
> ---
> drivers/xen/gntdev.c | 17 ++++++++++-------
> 1 file changed, 10 insertions(+), 7 deletions(-)
>
> I sent this in January, Boris sent an almost identical patch
> as http://www.gossamer-threads.com/lists/xen/devel/414056
> but the bug remains present in mainline and linux-next as of
> Feb 25.
>
> Could you apply one of the patches before the bug makes it
> into v4.5?
David wanted to shrink the structure size instead:
http://www.gossamer-threads.com/lists/xen/devel/414535
-boris
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