Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 31 May 2022 13:58:31 +0100 | From | Matthew Wilcox <> | Subject | Re: [PATCH v4 1/4] mm: reduce the rcu lock duration |
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On Mon, May 30, 2022 at 07:30:13PM +0800, 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.
But why bother? You know the RCU read lock isn't a "real" lock, right?
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