On Thu, Jul 28, 2016 at 11:35:34AM -0700, Darrick J. Wong wrote: > Kirill A. Shutemov reports that the kernel doesn't try to cap dest_count > in any way, and uses the number to allocate kernel memory. This causes > high order allocation warnings in the kernel log if someone passes in a > big enough value. We should clamp the allocation at PAGE_SIZE to avoid > stressing the VM. > > The two existing users of the dedupe ioctl never send more than 120 > requests, so we can safely clamp dest_range at PAGE_SIZE, because with > 4k pages we can handle up to 127 dedupe candidates. Given the max > extent length of 16MB, we can end up doing 2GB of IO which is plenty. Looks fine, Reviewed-by: Christoph Hellwig <hch@xxxxxx> > @@ -582,6 +582,10 @@ static int ioctl_file_dedupe_range(struct file *file, void __user *arg) This function returns long in mainline. Maybe you should resend your return type fix to Al while you're at it? -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
