linux-kernel - Re: KCSAN: data-race in __alloc_file / __alloc

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Date:   Fri, 8 Nov 2019 13:36:23 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        syzbot <syzbot+3ef049d50587836c0606@...kaller.appspotmail.com>,
        Marco Elver <elver@...gle.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: KCSAN: data-race in __alloc_file / __alloc_file

On Fri, Nov 8, 2019 at 12:53 PM Eric Dumazet <edumazet@...gle.com> wrote:
>
> per cpu SNMP counters mostly, with no IRQ safety requirements.
>
> Note that this could be implemented using local{64}_add() on arches like x86_64,
> while others might have to fallback to WRITE_ONCE(variable, variable + add)

raw_cpu_add()?

We already use those for vm_counters where we intentionally accept races.

              Linus