linux-kernel - Re: [PATCH 0/4] kvfree_rcu() and _LOCK_NESTING/_PREEMPT

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Message-ID: <20200918221528.GX29330@paulmck-ThinkPad-P72>
Date:   Fri, 18 Sep 2020 15:15:28 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     "Uladzislau Rezki (Sony)" <urezki@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, RCU <rcu@...r.kernel.org>,
        linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        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>
Subject: Re: [PATCH 0/4] kvfree_rcu() and _LOCK_NESTING/_PREEMPT_RT

On Fri, Sep 18, 2020 at 09:48:13PM +0200, Uladzislau Rezki (Sony) wrote:
> Hello, folk!
> 
> This is another iteration of fixing kvfree_rcu() issues related
> to CONFIG_PROVE_RAW_LOCK_NESTING and CONFIG_PREEMPT_RT configs.
> 
> The first discussion is here https://lkml.org/lkml/2020/8/9/195.
> 
> - As an outcome of it, there was a proposal from Peter, instead of
> using a speciall "lock-less" flag it is better to move lock-less
> access to the pcplist to the separate function.
> 
> - To add a special worker thread that does prefetching of pages
> if a per-cpu page cache is depleted(what is absolutely normal). 
> 
> As usual, thank you for paying attention to it and your help!
> 
> Uladzislau Rezki (Sony) (4):
>   rcu/tree: Add a work to allocate pages from regular context
>   mm: Add __rcu_alloc_page_lockless() func.
>   rcu/tree: use __rcu_alloc_page_lockless() func.
>   rcu/tree: Use schedule_delayed_work() instead of WQ_HIGHPRI queue

Thank you, Uladzislau!

I have pulled this into -rcu for review and testing.  I have not yet
assigned it to an intended release.

							Thanx, Paul

>  include/linux/gfp.h |  1 +
>  kernel/rcu/tree.c   | 90 ++++++++++++++++++++++++---------------------
>  mm/page_alloc.c     | 82 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 132 insertions(+), 41 deletions(-)
> 
> -- 
> 2.20.1
>