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Date:   Thu, 8 Feb 2018 10:56:48 -0800
From:   Matthew Wilcox <willy@infradead.org>
To:     Daniel Micay <danielmicay@gmail.com>
Cc:     Jann Horn <jannh@google.com>, linux-mm@kvack.org,
        Kernel Hardening <kernel-hardening@lists.openwall.com>,
        kernel list <linux-kernel@vger.kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [RFC] Warn the user when they could overflow mapcount
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On Thu, Feb 08, 2018 at 01:05:33PM -0500, Daniel Micay wrote:
> The standard map_max_count / pid_max are very low and there are many
> situations where either or both need to be raised.

[snip good reasons]

> I do think the default value in the documentation should be fixed but
> if there's a clear problem with raising these it really needs to be
> fixed. Google either of the sysctl names and look at all the people
> running into issues and needing to raise them. It's only going to
> become more common to raise these with people trying to use lots of
> fine-grained sandboxing. Process-per-request is back in style.

So we should make the count saturate instead, then?  That's going to
be interesting.