linux-kernel - bpfilter logging write errors in dmesg

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Date:   Mon, 27 Jul 2020 12:46:36 +0200
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     Christoph Hellwig <hch@....de>
Cc:     linux-kernel@...r.kernel.org
Subject: bpfilter logging write errors in dmesg

Hey Christoph,

Seems that commit
6955a76fbcd5 ("bpfilter: switch to kernel_write")
causes bpfilter to spew these useless messages in dmesg?

[   26.356824] Started bpfilter
[   26.357059] bpfilter: write fail -22
[   26.396244] Started bpfilter
[   26.396325] bpfilter: Loaded bpfilter_umh pid 637
[   26.396542] bpfilter: write fail -22
[   26.409588] bpfilter: Loaded bpfilter_umh pid 638
[   26.410790] Started bpfilter
[   26.410960] bpfilter: write fail -22
[   26.445718] Started bpfilter
[   26.445799] bpfilter: Loaded bpfilter_umh pid 640
[   26.445983] bpfilter: write fail -22
[   26.451122] bpfilter: read fail 0
[   26.496497] bpfilter: Loaded bpfilter_umh pid 648
[   26.497889] Started bpfilter
[   26.750028] bpfilter: write fail -22
[   26.768400] Started bpfilter
[   26.768496] bpfilter: Loaded bpfilter_umh pid 661
[   26.768699] bpfilter: write fail -22
[   26.806550] Started bpfilter
[   26.806616] bpfilter: Loaded bpfilter_umh pid 663
[   26.864708] bpfilter: write fail -22
[   26.872345] bpfilter: Loaded bpfilter_umh pid 666
[   26.873072] Started bpfilter
[   26.873194] bpfilter: write fail -22
[   27.295514] kauditd_printk_skb: 22 callbacks suppressed

This is on a pure v5.8-rc7 via make bindep-pkg. I'm not using bpfilter
in any shape or form afaict and haven't seen those messages before and
this seems to be the last change I see.

Thanks!
Christian