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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> 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> X-Stat-Signature: p4wr5k4t3nm9t698f5sgsjn1y8gnwg6t X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: E9C0B140002 X-HE-Tag: 1779722290-540069 X-HE-Meta: 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 AKmsc+I2 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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