From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id E343C6B0038 for ; Tue, 26 Sep 2017 05:43:47 -0400 (EDT) Received: by mail-wm0-f69.google.com with SMTP id u138so11358801wmu.2 for ; Tue, 26 Sep 2017 02:43:47 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id n2sor4580352edd.3.2017.09.26.02.43.46 for (Google Transport Security); Tue, 26 Sep 2017 02:43:46 -0700 (PDT) Date: Tue, 26 Sep 2017 12:43:44 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCHv2] mm: Account pud page tables Message-ID: <20170926094344.t4cws4v4vrie5de5@node.shutemov.name> References: <20170925073913.22628-1-kirill.shutemov@linux.intel.com> <20170925115430.zccesf75c4ysaznb@dhcp22.suse.cz> <20170925130715.kebf5e3xjctpcalp@node.shutemov.name> <20170925135305.ydeeyapav2s36ifj@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170925135305.ydeeyapav2s36ifj@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: "Kirill A. Shutemov" , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka On Mon, Sep 25, 2017 at 03:53:05PM +0200, Michal Hocko wrote: > On Mon 25-09-17 16:07:15, Kirill A. Shutemov wrote: > > On Mon, Sep 25, 2017 at 01:54:30PM +0200, Michal Hocko wrote: > > > On Mon 25-09-17 10:39:13, Kirill A. Shutemov wrote: > > > > On machine with 5-level paging support a process can allocate > > > > significant amount of memory and stay unnoticed by oom-killer and > > > > memory cgroup. The trick is to allocate a lot of PUD page tables. > > > > We don't account PUD page tables, only PMD and PTE. > > > > > > > > We already addressed the same issue for PMD page tables, see > > > > dc6c9a35b66b ("mm: account pmd page tables to the process"). > > > > Introduction 5-level paging bring the same issue for PUD page tables. > > > > > > > > The patch expands accounting to PUD level. > > > > > > OK, we definitely need this or something like that but I really do not > > > like how much code we actually need for each pte level for accounting. > > > Do we really need to distinguish each level? Do we have any arch that > > > would use a different number of pages to back pte/pmd/pud? > > > > Looks like we actually do. At least on mips. See PMD_ORDER/PUD_ORDER. > > Hmm, but then oom_badness does consider them a single page which is > wrong. I haven't checked other users. Anyway even if we've had different > sizes why cannot we deal with this in callers. They know which level of > page table they allocate/free, no? So do you want to see single counter for all page table levels? Do we have anybody who relies on VmPTE/VmPMD now? -- Kirill A. Shutemov -- 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