Re: [PATCH] maple_tree: Remove rcu_read_lock() from mt_validate()

From: Matthew Wilcox
Date: Tue Aug 20 2024 - 18:54:15 EST


On Wed, Aug 21, 2024 at 06:38:45AM +0800, Hillf Danton wrote:

Hillf, your email client is STILL broken. It's using the same message
ID as the email it's replying to, which causes all kinds of problems.
Please fix it or change to a different client.

> On Tue, 20 Aug 2024 13:54:17 -0400 "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
> >
> > The write lock should be held when validating the tree to avoid updates
> > racing with checks. Holding the rcu read lock during a large tree
> > validation may also cause a prolonged rcu read window.
> >
> >From the rcu stall's view, holding spin lock plays the same role of rcu
> read lock, so what are you fixing by simply dropping rcu read lock?

He's not holding a spinlock, he's holding a mutex, which has very
different properties.