Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <20171127162207.GA8265@bombadil.infradead.org>
References: <23066.59196.909026.689706@gargle.gargle.HOWL> <20171127101232.ykriowhatecnvjvg@dhcp22.suse.cz>
 <20171127162207.GA8265@bombadil.infradead.org>
From:   Mikael Pettersson <mikpelinux@gmail.com>
Date:   Mon, 27 Nov 2017 20:28:27 +0100
Message-ID: <CAM43=SOAU2-qTB2cHeZs5xGzPFKwoqtTafqtw+BqCP9cbQDUOQ@mail.gmail.com>
Subject: Re: [PATCH] mm: disable `vm.max_map_count' sysctl limit
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Michal Hocko <mhocko@kernel.org>, linux-mm@kvack.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org,
        Linux API <linux-api@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Nov 27, 2017 at 5:22 PM, Matthew Wilcox <willy@infradead.org> wrote:
>> Could you be more explicit about _why_ we need to remove this tunable?
>> I am not saying I disagree, the removal simplifies the code but I do not
>> really see any justification here.
>
> I imagine he started seeing random syscalls failing with ENOMEM and
> eventually tracked it down to this stupid limit we used to need.

Exactly, except the origin (mmap() failing) was hidden behind layers upon layers
of user-space memory management code (not ours), which just said "failed to
allocate N bytes" (with N about 0.001% of the free RAM).  And it
wasn't reproducible.

From 1585248055825199290@xxx Mon Nov 27 19:19:15 +0000 2017
X-GM-THRID: 1585145582796220475
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread