From: "Paul E. McKenney" <paulmck@kernel.org>
To: Uladzislau Rezki <urezki@gmail.com>
Cc: Zqiang <qiang1.zhang@intel.com>,
frederic@kernel.org, joel@joelfernandes.org,
qiang.zhang1211@gmail.com, rcu@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rcu/kvfree: Make fill page cache start from krcp->nr_bkv_objs
Date: Thu, 13 Apr 2023 11:50:16 -0700 [thread overview]
Message-ID: <56ffa1b8-578b-402c-86eb-2d3a05235896@paulmck-laptop> (raw)
In-Reply-To: <ZDfGPQfFhMdajJRC@pc636>
On Thu, Apr 13, 2023 at 11:07:09AM +0200, Uladzislau Rezki wrote:
> On Wed, Apr 12, 2023 at 10:31:27PM +0800, Zqiang wrote:
> > The fill_page_cache_func() is invoked and start from zero to
> > allocate nr_pages of page, if the kfree_rcu_work() executes before
> > the fill_page_cache_func(), the krcp->nr_bkv_objs is updated before
> > enter for-loop and equal to nr_pages, since the page is allocated
> > first, and then check the krcp->nr_bkv_objs in put_cached_bnode(),
> > this produces a meaningless __get_free_page() call, this commit
> > therefore make allocate page start from krcp->nr_bkv_objs and
> > check krcp->nr_bkv_objs before allocate page.
> >
> > Signed-off-by: Zqiang <qiang1.zhang@intel.com>
> > ---
> > kernel/rcu/tree.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 41daae3239b5..dcb86f9f2dd6 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -3223,7 +3223,7 @@ static void fill_page_cache_func(struct work_struct *work)
> > nr_pages = atomic_read(&krcp->backoff_page_cache_fill) ?
> > 1 : rcu_min_cached_objs;
> >
> > - for (i = 0; i < nr_pages; i++) {
> > + for (i = READ_ONCE(krcp->nr_bkv_objs); i < nr_pages; i++) {
> > bnode = (struct kvfree_rcu_bulk_data *)
> > __get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
> >
> > --
> > 2.32.0
> >
> Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Queued and pushed, thank you both!
Thanx, Paul
prev parent reply other threads:[~2023-04-13 18:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-12 14:31 [PATCH] rcu/kvfree: Make fill page cache start from krcp->nr_bkv_objs Zqiang
2023-04-13 9:07 ` Uladzislau Rezki
2023-04-13 18:50 ` Paul E. McKenney [this message]
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