Message ID | 1456435523-287763-1-git-send-email-arnd@arndb.de (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
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
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; }
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?