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Tue, 02 Jun 2026 15:18:50 -0700 (PDT) Received: from localhost ([212.73.77.104]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-4601f2dcae2sm2882120f8f.6.2026.06.02.15.18.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 Jun 2026 15:18:50 -0700 (PDT) From: Askar Safin To: kas@kernel.org Cc: Liam.Howlett@oracle.com, aarcange@redhat.com, akpm@linux-foundation.org, corbet@lwn.net, david@kernel.org, jthoughton@google.com, kernel-team@meta.com, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, ljs@kernel.org, pbonzini@redhat.com, peterx@redhat.com, rppt@kernel.org, seanjc@google.com, sj@kernel.org, skhan@linuxfoundation.org, surenb@google.com, usama.arif@linux.dev, vbabka@kernel.org, ziy@nvidia.com Subject: Re: [PATCH v6 14/15] selftests/mm: add userfaultfd RWP tests Date: Wed, 3 Jun 2026 01:18:31 +0300 Message-ID: <20260602221831.77366-1-safinaskar@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260529172716.357179-15-kas@kernel.org> References: <20260529172716.357179-15-kas@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 624CC4000C X-Rspam-User: X-Stat-Signature: q4g6pykmsh44dt8pe81gt44y4uuhg5gr X-Rspamd-Server: rspam09 X-HE-Tag: 1780438732-250867 X-HE-Meta: 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 RLqSXGkm 0540zOUYlaukPwgGFCBqlaTHPjkEsAw4kGKaNBgi/G+Jvh+S3iDSFTh7ruqxPOYmDbqJpMToMw+1JbvkkIdRBv9V/UNnGTNU6y+HS8//XjamCHSswYTS1jQeA3b7v/vOPI24uJM2Vtl24Ioa02/EFVdiQdCxV8qKi8Ry/EwSG99+4GBzpmYQJOMQZ5NQ/PIVWmuTBHloK9hDVIbOGZd9RlcWQEXJ1OQ57zqkjoFBaIx9sp791+2t8yc1hcyWEKC4ro1mdgO532Q/eTRpeLhsl5FAUtGRrQfpMxdEz+7XZegV2cQtvSV8BFIlR1PUdObJVn+NEYky9pCi4TsJkKsRCC4wMjxxNb+GoR7ryK/2nmaquLnai/EvWryzIksyd9AMckw5YsXpkMD2DvSiDb8o096LplabBJfcDRbeh Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: "Kiryl Shutsemau (Meta)" : > +/* > + * Test that GUP resolves through protnone PTEs (async mode). > + * vmsplice() into a pipe pins user pages via get_user_pages_fast() -- > + * unlike write(), which goes through copy_from_user() and ordinary > + * hardware page faults -- so it exercises gup_can_follow_protnone() on > + * the RW-protected PTE. In async mode the kernel auto-restores > + * permissions and GUP returns the page. > + */ Note that I recently submitted a patch, which makes vmsplice equivalent to preadv2/pwritev2, and it was accepted to next. For now it is just an experiment, it is possible it will be reverted. https://lore.kernel.org/all/20260601-aufweichen-dissens-ausrechnen-0d9b84728113@brauner/ -- Askar Safin