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Sun, 24 Dec 2023 13:44:04 -0800 (PST) Date: Sun, 24 Dec 2023 13:44:03 -0800 (PST) From: David Rientjes To: Pasha Tatashin cc: akpm@linux-foundation.org, alim.akhtar@samsung.com, alyssa@rosenzweig.io, asahi@lists.linux.dev, baolu.lu@linux.intel.com, bhelgaas@google.com, cgroups@vger.kernel.org, corbet@lwn.net, david@redhat.com, dwmw2@infradead.org, hannes@cmpxchg.org, heiko@sntech.de, iommu@lists.linux.dev, jernej.skrabec@gmail.com, jonathanh@nvidia.com, joro@8bytes.org, krzysztof.kozlowski@linaro.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-rockchip@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-sunxi@lists.linux.dev, linux-tegra@vger.kernel.org, lizefan.x@bytedance.com, marcan@marcan.st, mhiramat@kernel.org, m.szyprowski@samsung.com, paulmck@kernel.org, rdunlap@infradead.org, robin.murphy@arm.com, samuel@sholland.org, suravee.suthikulpanit@amd.com, sven@svenpeter.dev, thierry.reding@gmail.com, tj@kernel.org, tomas.mudrunka@gmail.com, vdumpa@nvidia.com, wens@csie.org, will@kernel.org, yu-cheng.yu@intel.com Subject: Re: [PATCH v2 10/10] iommu: account IOMMU allocated memory In-Reply-To: Message-ID: References: <20231130201504.2322355-1-pasha.tatashin@soleen.com> <20231130201504.2322355-11-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Stat-Signature: sj7ykdhjqtxzhahyz1opsk3uksy8j6m9 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: ECBCF20002 X-Rspam-User: X-HE-Tag: 1703454245-567017 X-HE-Meta: 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 mBUlvhXw 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 15 Dec 2023, Pasha Tatashin wrote: > > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > > > index 3f85254f3cef..e004e05a7cde 100644 > > > --- a/Documentation/admin-guide/cgroup-v2.rst > > > +++ b/Documentation/admin-guide/cgroup-v2.rst > > > @@ -1418,7 +1418,7 @@ PAGE_SIZE multiple when read back. > > > sec_pagetables > > > Amount of memory allocated for secondary page tables, > > > this currently includes KVM mmu allocations on x86 > > > - and arm64. > > > + and arm64 and IOMMU page tables. > > > > Hmm, if existing users are parsing this field and alerting when it exceeds > > an expected value (a cloud provider, let's say), is it safe to add in a > > whole new set of page tables? > > > > I understand the documentation allows for it, but I think potential impact > > on userspace would be more interesting. > > Hi David, > > This is something that was discussed at LPC'23. I also was proposing a > separate counter for iommu page tables, but it was noted that we > specifically have sec_pagetables called this way to include all non > regular CPU page tables, and we should therefore account for them > together. > > Please also see this discussion from the previous version of this patch series: > https://lore.kernel.org/all/CAJD7tkb1FqTqwONrp2nphBDkEamQtPCOFm0208H3tp0Gq2OLMQ@mail.gmail.com/ > Gotcha, I think that makes sense. When sec_pagetables was introduced, I can understand the need to account for non-primary pagetables separately because of the long-standing behavior. In that sense, sec_pagetables becomes a dumping ground for "all other page tables" which IOMMU would naturally include. So this looks good to me. Acked-by: David Rientjes