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Mon, 25 May 2026 11:18:07 -0400 (EDT) Date: Mon, 25 May 2026 16:18:06 +0100 From: Kiryl Shutsemau To: sashiko-reviews@lists.linux.dev Cc: kvm@vger.kernel.org, akpm@linux-foundation.org, rppt@kernel.org, peterx@redhat.com, david@kernel.org, ljs@kernel.org, surenb@google.com, vbabka@kernel.org, Liam.Howlett@oracle.com, ziy@nvidia.com, corbet@lwn.net, skhan@linuxfoundation.org, seanjc@google.com, pbonzini@redhat.com, jthoughton@google.com, aarcange@redhat.com, sj@kernel.org, usama.arif@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v4 07/14] mm: handle VM_UFFD_RWP in khugepaged, rmap, and GUP Message-ID: References: <20260525113737.1942478-8-kas@kernel.org> <20260525131923.11A1B1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260525131923.11A1B1F000E9@smtp.kernel.org> On Mon, May 25, 2026 at 01:19:22PM +0000, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [High] GUP enters an infinite loop when using FOLL_FORCE on an > inaccessible (PROT_NONE) VMA that has VM_UFFD_RWP enabled. Confirmed. RWP resolution restores vm_page_prot, which is PAGE_NONE on a PROT_NONE VMA -- the page never becomes accessible and FOLL_FORCE loops. Will fix in v5 by rejecting the registration up front in vma_can_userfault(): + if ((vm_flags & VM_UFFD_RWP) && !vma_is_accessible(vma)) + return false; > -- > Sashiko AI review · https://sashiko.dev/#/patchset/20260525113737.1942478-1-kas@kernel.org?part=7 -- Kiryl Shutsemau / Kirill A. Shutemov