linux-kernel - Re: [PATCH v2 09/16] rcu/tree: Maintain separate array for vmalloc ptrs

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Date:   Thu, 18 Jun 2020 20:34:48 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Uladzislau Rezki <urezki@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Theodore Y . Ts'o" <tytso@....edu>,
        Joel Fernandes <joel@...lfernandes.org>,
        RCU <rcu@...r.kernel.org>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>
Subject: Re: [PATCH v2 09/16] rcu/tree: Maintain separate array for vmalloc
 ptrs

> > > 
> > > I suspect that he would like to keep the tracing.
> > > 
> > > It might be worth trying the branches, given that they would be constant
> > > and indexed by "i".  The compiler might well remove the indirection.
> > > 
> > > The compiler guys brag about doing so, which of course might or might
> > > not have any correlation to a given compiler actually doing so.  :-/
> > > 
> > > Having a vfree_bulk() might well be useful, but I would feel more
> > > confidence in that if there were other callers of kfree_bulk().
> > >
> > Hmm... I think replacing that with vfree_bulk() is a good idea though.
> 
> In other words, get rid of kfree_bulk() in favor of vfree_bulk()?
> 
kfree_bulk() does not understand vmalloc memory. vfree_bulk() should
be implemented to release vmalloc's pointers. On i high level it will
be used the same way as kfree_bulk() but for vmalloc ptrs. only.

> > > But again, either way, future work as far as this series is concerned.
> > > 
> > What do you mean: is concerned?
> 
> Apologies for the strange English.  How about this?
> 
> "This series is OK as is.  Any comments above did not prevent me from
> taking these patches, but instead discuss possible future work."
> 
That is perfectly clear to me :)

> > We are planning to implement kfree_rcu() to be integrated directly into
> > SLAB: SLAB, SLUB, SLOB. So, there are plenty of future work :)
>
> And I am glad that this is still the goal.  ;-)
>
:)

--
Vlad Rezki