On Mon, Oct 05, 2020 at 12:50:49AM +0300, Jarkko Sakkinen wrote:
> What is shoukd take is encl->lock.
>
> The loop was pre-v36 like:
>
> idx_start = PFN_DOWN(start);
> idx_end = PFN_DOWN(end - 1);
>
> for (idx = idx_start; idx <= idx_end; ++idx) {
> mutex_lock(&encl->lock);
> page = radix_tree_lookup(&encl->page_tree, idx);
> mutex_unlock(&encl->lock);
>
> if (!page || (~page->vm_max_prot_bits & vm_prot_bits))
> return -EACCES;
> }
>
> Looking at xarray.h and filemap.c, I'm thinking something along the
> lines of:
>
> for (idx = idx_start; idx <= idx_end; ++idx) {
> mutex_lock(&encl->lock);
> page = xas_find(&xas, idx + 1);
> mutex_unlock(&encl->lock);
>
> if (!page || (~page->vm_max_prot_bits & vm_prot_bits))
> return -EACCES;
> }
>
> Does this look about right?
Not really ...
int ret = 0;
mutex_lock(&encl->lock);
rcu_read_lock();
while (xas.index < idx_end) {
page = xas_next(&xas);
if (!page || (~page->vm_max_prot_bits & vm_prot_bits))
ret = -EACCESS;
break;
}
}
rcu_read_unlock();
mutex_unlock(&encl->lock);
return ret;
... or you could rework to use the xa_lock instead of encl->lock.
I don't know how feasible that is for you.
