linux-kernel - Re: [PATCH] mm: disable `vm.max_map

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Message-ID: <20171127195732.3hkfx57d3ytyccvp@dhcp22.suse.cz>
Date:   Mon, 27 Nov 2017 20:57:32 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Andi Kleen <ak@...ux.intel.com>
Cc:     Mikael Pettersson <mikpelinux@...il.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-api@...r.kernel.org
Subject: Re: [PATCH] mm: disable `vm.max_map_count' sysctl limit

On Mon 27-11-17 19:32:18, Michal Hocko wrote:
> On Mon 27-11-17 09:25:16, Andi Kleen wrote:
[...]
> > The reason the limit was there originally because it allows a DoS
> > attack against the kernel by filling all unswappable memory up with VMAs.
> 
> We can reduce the effect by accounting vmas to memory cgroups.

As it turned out we already do.
	vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);

-- 
Michal Hocko
SUSE Labs