Re: [PATCH v4 1/4] mm: reduce the rcu lock duration

[David Hildenbrand]

On 30.05.22 13:30, Miaohe Lin wrote:
> Commit 3268c63eded4 ("mm: fix move/migrate_pages() race on task struct")
> extends the period of the rcu_read_lock until after the permissions checks
> are done to prevent the task pointed to from changing from under us. But
> the task_struct refcount is also taken at that time, the reference to task
> is guaranteed to be stable. So it's unnecessary to extend the period of
> the rcu_read_lock. Release the rcu lock after task refcount is successfully
> grabbed to reduce the rcu holding time.
> 
> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> Cc: Huang Ying <ying.huang@xxxxxxxxx>
> Cc: David Howells <dhowells@xxxxxxxxxx>
> Cc: Christoph Lameter <cl@xxxxxxxxx>


Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

-- 
Thanks,

David / dhildenb