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Date:   Mon, 3 Oct 2022 16:25:56 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Yury Norov <yury.norov@gmail.com>
Cc:     netdev@vger.kernel.org, "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Menglong Dong <imagedong@tencent.com>,
        Kuniyuki Iwashima <kuniyu@amazon.com>,
        Petr Machata <petrm@nvidia.com>
Subject: Re: [PATCH 0/4] net: drop netif_attrmask_next*()
Message-ID: <20221003162556.10a80858@kernel.org>
In-Reply-To: <YzsluT4ET0zyjCtp@yury-laptop>
References: <20221002151702.3932770-1-yury.norov@gmail.com>
        <20221003095048.1a683ba7@kernel.org>
        <YzsluT4ET0zyjCtp@yury-laptop>
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On Mon, 3 Oct 2022 11:11:05 -0700 Yury Norov wrote:
> On Mon, Oct 03, 2022 at 09:50:48AM -0700, Jakub Kicinski wrote:
> > On Sun,  2 Oct 2022 08:16:58 -0700 Yury Norov wrote:  
> > > netif_attrmask_next_and() generates warnings if CONFIG_DEBUG_PER_CPU_MAPS
> > > is enabled.  
> > 
> > Could you describe the nature of the warning? Is it a false positive 
> > or a legit warning?
> > 
> > If the former perhaps we should defer until after the next merge window.  
> 
> The problem is that netif_attrmask_next_and() is called with
> n == nr_cpu_ids-1, which triggers cpu_max_bits_warn() after this:
> 
> https://lore.kernel.org/netdev/20220926103437.322f3c6c@kernel.org/

I see. Is that patch merged and on it's way? Perhaps we can just revert
it and try again after the merge window?

> Underlying bitmap layer handles this correctly, so this wouldn't make
> problems for people. But this is not a false-positive.