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a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755087266; bh=tLOV7MuxuGZuAFjpe/xUc874h2DrbSyeczMhXjDQFOI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rujDt7wsKQqVTbCwQrtiVRdM2aH76LameWGzvTdZ5npEBlrG95aNQxa3fQpNRodhk QJbxh/7YOXP2RZlRsBQ3Euf+xwHlnxbyvDua1jB4H6D5yGcYFwDUM1uYw6W6cryK3z Pug/jEnZ7mb8BeSzL61ybm0Sudo+Z5LhYzcQFvOs= Date: Wed, 13 Aug 2025 14:14:23 +0200 From: Greg KH To: Pratyush Yadav Cc: Vipin Sharma , Pasha Tatashin , jasonmiu@google.com, graf@amazon.com, changyuanl@google.com, rppt@kernel.org, dmatlack@google.com, rientjes@google.com, corbet@lwn.net, rdunlap@infradead.org, ilpo.jarvinen@linux.intel.com, kanie@linux.alibaba.com, ojeda@kernel.org, aliceryhl@google.com, masahiroy@kernel.org, akpm@linux-foundation.org, tj@kernel.org, yoann.congal@smile.fr, mmaurer@google.com, roman.gushchin@linux.dev, chenridong@huawei.com, axboe@kernel.dk, mark.rutland@arm.com, jannh@google.com, vincent.guittot@linaro.org, hannes@cmpxchg.org, dan.j.williams@intel.com, david@redhat.com, joel.granados@kernel.org, rostedt@goodmis.org, anna.schumaker@oracle.com, song@kernel.org, zhangguopeng@kylinos.cn, linux@weissschuh.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, rafael@kernel.org, dakr@kernel.org, bartosz.golaszewski@linaro.org, cw00.choi@samsung.com, myungjoo.ham@samsung.com, yesanishhere@gmail.com, Jonathan.Cameron@huawei.com, quic_zijuhu@quicinc.com, aleksander.lobakin@intel.com, ira.weiny@intel.com, andriy.shevchenko@linux.intel.com, leon@kernel.org, lukas@wunner.de, bhelgaas@google.com, wagi@kernel.org, djeffery@redhat.com, stuart.w.hayes@gmail.com, lennart@poettering.net, brauner@kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, saeedm@nvidia.com, ajayachandra@nvidia.com, jgg@nvidia.com, parav@nvidia.com, leonro@nvidia.com, witu@nvidia.com Subject: Re: [PATCH v3 29/30] luo: allow preserving memfd Message-ID: <2025081351-tinsel-sprinkler-af77@gregkh> References: <20250807014442.3829950-1-pasha.tatashin@soleen.com> <20250807014442.3829950-30-pasha.tatashin@soleen.com> <20250813063407.GA3182745.vipinsh@google.com> <2025081310-custodian-ashamed-3104@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: sabozraccbp3w5j9f738kwi1af6orqi6 X-Rspam-User: X-Rspamd-Queue-Id: E913340005 X-Rspamd-Server: rspam02 X-HE-Tag: 1755087267-569119 X-HE-Meta: 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 hIRLWRRK x/NarDW5lBBJi9xDSoA4D5SgPxcAlqLsqPQkjKhXW41DfIPzpwwH8aM0d4+GRu5LVIZWLDOP6Gb9W6ElkLZbCXimeVRKmXh9qDI2e/AHB+a10atI4qJkaU9L6N9GnfB+2dhtf8LBgICjWVj+smiXOY1N1YQUuaexPxneh3CV7eliVccW7AmJPpwjKv37tTr9wITrpX2wI2dGYRhf6PHWa1V5EdjvORD/oXlHgghNkXHfJJzTeOb51gC9lOzMg95tPvk81KACJurs4v9V6QC0cjkEt+uXHTZIPVh0UOM4E5Bw160F5Xe65d4oxjYt9ThhuMBevBUuRIP9v8UFTcl3mauJGDomqPq96BGoMYho7RQXaep6oPYhBnVZeDeq0JcIgE8MZewb1hSQLft4= 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 Wed, Aug 13, 2025 at 02:02:07PM +0200, Pratyush Yadav wrote: > On Wed, Aug 13 2025, Greg KH wrote: > > > On Tue, Aug 12, 2025 at 11:34:37PM -0700, Vipin Sharma wrote: > >> On 2025-08-07 01:44:35, Pasha Tatashin wrote: > >> > From: Pratyush Yadav > >> > +static void memfd_luo_unpreserve_folios(const struct memfd_luo_preserved_folio *pfolios, > >> > + unsigned int nr_folios) > >> > +{ > >> > + unsigned int i; > >> > + > >> > + for (i = 0; i < nr_folios; i++) { > >> > + const struct memfd_luo_preserved_folio *pfolio = &pfolios[i]; > >> > + struct folio *folio; > >> > + > >> > + if (!pfolio->foliodesc) > >> > + continue; > >> > + > >> > + folio = pfn_folio(PRESERVED_FOLIO_PFN(pfolio->foliodesc)); > >> > + > >> > + kho_unpreserve_folio(folio); > >> > >> This one is missing WARN_ON_ONCE() similar to the one in > >> memfd_luo_preserve_folios(). > > > > So you really want to cause a machine to reboot and get a CVE issued for > > this, if it could be triggered? That's bold :) > > > > Please don't. If that can happen, handle the issue and move on, don't > > crash boxes. > > Why would a WARN() crash the machine? That is what BUG() does, not > WARN(). See 'panic_on_warn' which is enabled in a few billion Linux systems these days :(