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From:   Xie He <xie.he.0141@gmail.com>
Date:   Fri, 9 Apr 2021 03:14:00 -0700
Message-ID: <CAJht_EOmcOdKGKnoUQDJD-=mnHOK0MKiV0+4Epty5H5DMED-qw@mail.gmail.com>
Subject: Re: Problem in pfmemalloc skb handling in net/core/dev.c
To:     Eric Dumazet <eric.dumazet@gmail.com>
Cc:     Mel Gorman <mgorman@techsingularity.net>,
        Mel Gorman <mgorman@suse.de>, jslaby@suse.cz,
        Neil Brown <neilb@suse.de>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Mike Christie <michaelc@cs.wisc.edu>,
        Eric B Munson <emunson@mgebm.net>,
        Sebastian Andrzej Siewior <sebastian@breakpoint.cc>,
        Christoph Lameter <cl@linux.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Fri, Apr 9, 2021 at 3:04 AM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
> Note that pfmemalloc skbs are normally dropped in sk_filter_trim_cap()
>
> Simply make sure your protocol use it.

It seems "sk_filter_trim_cap" needs an "struct sock" argument. Some of
my protocols act like a middle layer to another protocol and don't
have any "struct sock".

Also, I think this is a problem in net/core/dev.c, there are a lot of
old protocols that are not aware of pfmemalloc skbs. I don't think
it's a good idea to fix them one by one.