linux-kernel - Re: [syzbot] WARNING: refcount bug in memfd

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Message-ID: <CAHk-=wiJRdV-7NYvh+8mzDtuPvTg6PHHUedeVXjY92+gxhYJbw@mail.gmail.com>
Date:   Mon, 25 Oct 2021 10:00:22 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     syzbot <syzbot+75639e6a0331cd61d3e2@...kaller.appspotmail.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        jordy@...dyzomer.github.io, jordy@...ing.systems,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: [syzbot] WARNING: refcount bug in memfd_secret

On Sun, Oct 24, 2021 at 1:10 PM Matthew Wilcox <willy@...radead.org> wrote:
>
> I agree with you and suggested that if anybody really cares (I mean,
> you need a multi-TB machine to produce this problem) that we simply do
> what we did with the page refcount:

Ack. That looks like the right thing to do.

> +       if (atomic_read(&secretmem_users) < 0)
> +               return -ENFILE;

If somebody sends me a proper patch with a sign-off etc, I'll happily
apply that two-liner. Hint hint.

              Linus