linux-kernel - Re: [PATCH 06/16] mm/pagemap: Cleanup PREEMPT

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Date:   Thu, 29 Oct 2020 14:26:59 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Uladzislau Rezki <urezki@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, RCU <rcu@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Theodore Y . Ts'o" <tytso@....edu>,
        Joel Fernandes <joel@...lfernandes.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>,
        linux-mm@...ck.org
Subject: Re: [PATCH 06/16] mm/pagemap: Cleanup PREEMPT_COUNT leftovers

On Thu, Oct 29, 2020 at 09:57:17PM +0100, Uladzislau Rezki wrote:
> On Thu, Oct 29, 2020 at 05:50:09PM +0100, Uladzislau Rezki (Sony) wrote:
> > From: Thomas Gleixner <tglx@...utronix.de>
> > 
> > CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
> > removed. Cleanup the leftovers before doing so.
> > 
> > Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Cc: linux-mm@...ck.org
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> > ---
> >  include/linux/pagemap.h | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> > 
> > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> > index c77b7c31b2e4..cbfbe2bcca75 100644
> > --- a/include/linux/pagemap.h
> > +++ b/include/linux/pagemap.h
> > @@ -204,9 +204,7 @@ void release_pages(struct page **pages, int nr);
> >  static inline int __page_cache_add_speculative(struct page *page, int count)
> >  {
> >  #ifdef CONFIG_TINY_RCU
> > -# ifdef CONFIG_PREEMPT_COUNT
> > -	VM_BUG_ON(!in_atomic() && !irqs_disabled());
> > -# endif
> > +	VM_BUG_ON(preemptible())
> >  	/*
> >  	 * Preempt must be disabled here - we rely on rcu_read_lock doing
> >  	 * this for us.
> > -- 
> > 2.20.1
> > 
> Hello, Paul.
> 
> Sorry for a small mistake, it was fixed by you before, whereas i took an
> old version of the patch that is question. Please use below one instead of
> posted one:

We have all been there and done that!  ;-)

I will give this update a spin and see what happens.

							Thanx, Paul

> Author: Thomas Gleixner <tglx@...utronix.de>
> Date:   Mon Sep 14 19:25:00 2020 +0200
> 
>     mm/pagemap: Cleanup PREEMPT_COUNT leftovers
>     
>     CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
>     removed. Cleanup the leftovers before doing so.
>     
>     Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
>     Cc: Andrew Morton <akpm@...ux-foundation.org>
>     Cc: linux-mm@...ck.org
>     [ paulmck: Fix !SMP build error per kernel test robot feedback. ]
>     Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> 
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 7de11dcd534d..b3d9d9217ea0 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -168,9 +168,7 @@ void release_pages(struct page **pages, int nr);
>  static inline int __page_cache_add_speculative(struct page *page, int count)
>  {
>  #ifdef CONFIG_TINY_RCU
> -# ifdef CONFIG_PREEMPT_COUNT
> -       VM_BUG_ON(!in_atomic() && !irqs_disabled());
> -# endif
> +       VM_BUG_ON(preemptible());
>         /*
>          * Preempt must be disabled here - we rely on rcu_read_lock doing
>          * this for us.
> 
> --
> Vlad Rezki