From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id BBD466B0038 for ; Mon, 27 Nov 2017 15:52:13 -0500 (EST) Received: by mail-pg0-f70.google.com with SMTP id 190so29903099pgh.16 for ; Mon, 27 Nov 2017 12:52:13 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 3si24253622plm.768.2017.11.27.12.52.12 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 27 Nov 2017 12:52:12 -0800 (PST) Date: Mon, 27 Nov 2017 21:52:10 +0100 From: Michal Hocko Subject: Re: [PATCH] mm: disable `vm.max_map_count' sysctl limit Message-ID: <20171127205210.zmah36uliajnbjon@dhcp22.suse.cz> References: <23066.59196.909026.689706@gargle.gargle.HOWL> <20171127101232.ykriowhatecnvjvg@dhcp22.suse.cz> <87vahv8whv.fsf@linux.intel.com> <20171127183218.33zm666jw3uqkxdq@dhcp22.suse.cz> <20171127195732.3hkfx57d3ytyccvp@dhcp22.suse.cz> <20171127202121.GB3070@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171127202121.GB3070@tassilo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andi Kleen Cc: Mikael Pettersson , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org On Mon 27-11-17 12:21:21, Andi Kleen wrote: > On Mon, Nov 27, 2017 at 08:57:32PM +0100, Michal Hocko wrote: > > 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); > > That only helps if you have memory cgroups enabled. It would be a regression > to break the accounting on all the systems that don't. I agree. And I didn't say we should remove the existing limit. I am just saying that we can reduce existing problems by increasing the limit and relying on memcg accounting where possible. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org