Thanks Matthew for the review.
On 1/12/2022 6:49 PM, Matthew Wilcox wrote:
> On Wed, Jan 12, 2022 at 01:51:55PM +0530, Charan Teja Kalla wrote:
>>>>> + rcu_read_lock();
>>>>> + xas_for_each(&xas, page, end) {
>>>>> + if (!xa_is_value(page))
>>>>> + continue;
>>>>> + xas_pause(&xas);
>>>>> + rcu_read_unlock();
>>>>> +
>>>>> + page = shmem_read_mapping_page(mapping, xas.xa_index);
>>>>> + if (!IS_ERR(page))
>>>>> + put_page(page);
>>>>> +
>>>>> + rcu_read_lock();
>>>>> + if (need_resched()) {
>>>>> + xas_pause(&xas);
>>>>> + cond_resched_rcu();
>>>>> + }
>>>>> + }
>>>>> + rcu_read_unlock();
>>> Even the xarray documentation says that: If most entries found during a
>>> walk require you to call xas_pause(), the xa_for_each() iterator may be
>>> more appropriate.
>
> Yes. This should obviously be an xa_for_each() loop.
>
ACK.
>>> Since every value entry found in the xarray requires me to do the
>>> xas_pause(), I do agree that xa_for_each() is the appropriate call here.
>>> Will switch to this in the next spin. Waiting for further review
>>> comments on this patch.
>>
>> I also found the below documentation:
>> xa_for_each() will spin if it hits a retry entry; if you intend to see
>> retry entries, you should use the xas_for_each() iterator instead.
>>
>> Since retry entries are expected, I should be using the xas_for_each()
>> with the corrections you had pointed out. Isn't it?
>
> No. You aren't handling retry entries at all; you clearly don't
> expect to see them. Just let the XArray code handle them itself.
ACK.
>
