Re: [PATCH] ia64/err-inject: Use get_user_pages_fast()

[Davidlohr Bueso]

Andrew, if you're ok with the patch below, could it be routed
your way?

Thanks,
Davidlohr

On Mon, 22 Jan 2018, Davidlohr Bueso wrote:

> At the point of sysfs callback, the call to gup is
> done without mmap_sem (or any lock for that matter).
> This is racy. As such, use the get_user_pages_fast()
> alternative and safely avoid taking the lock, if possible.
>
> Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
> ---
> arch/ia64/kernel/err_inject.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/ia64/kernel/err_inject.c b/arch/ia64/kernel/err_inject.c
> index 85bba43e7d5d..658a8e06a69b 100644
> --- a/arch/ia64/kernel/err_inject.c
> +++ b/arch/ia64/kernel/err_inject.c
> @@ -142,7 +142,7 @@ store_virtual_to_phys(struct device *dev, struct device_attribute *attr,
> 	u64 virt_addr=simple_strtoull(buf, NULL, 16);
> 	int ret;
>
> -	ret = get_user_pages(virt_addr, 1, FOLL_WRITE, NULL, NULL);
> +	ret = get_user_pages_fast(virt_addr, 1, FOLL_WRITE, NULL);
> 	if (ret<=0) {
> #ifdef ERR_INJ_DEBUG
> 		printk("Virtual address %lx is not existing.\n",virt_addr);
> --
> 2.13.6