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AJvYcCWJZ3iVxuCy2NcsdZDc2g7Wn972QOYwkBIllabfCHT3lzIbJJzurP1hpyd44LIo2OLkxOFwHJe4wQ==@kvack.org X-Gm-Message-State: AOJu0Yy9lydtZLCneJOoONEK2Xl0PEfYYb26TybDu9f+/sQSQGRD+a00 vdAFFCdmHiJcp+HmNoS7FwpIpIEANxkY3jpCq5e44asbaHVqgu2TV5TCDeFsTkpzeCdASO2TVmZ J3R1jlGgwb1toPnqIc22AlzrrKXdmm6GWY25v8faIB9/HPDyI3tozrdAZ X-Gm-Gg: ASbGncthNExbmUZcvBggjd82IlwsZzXcvfd4RLBROdLeBdUE0s2iEPQbYK7CkmnPkLa j0+C6z+kBkN5l2laLL9aBNNxTbLFUAqi2223e65xDvze40kNhsq5+4DzEVQRqDE9StPI2Em+O0J PMcEsQqlDt8zt9NXccBJVBTq/jKNWDGriLfuMJ3v5nOkCL/fZUY3d6rzBpqArGHfdbOwwjTuImD L2tpoW5I1VOoWk4mVgxlZM8HVzIwuSGBDE= X-Google-Smtp-Source: AGHT+IHu/Jxe0tRupMk8sata71Dj4GlEaCewOSkFs48tGZQjsE22y5CxcO9LxASkhWClWF59p30fdxQ7Yp6zw9xnWhg= X-Received: by 2002:a05:6402:26d1:b0:601:f23b:a377 with SMTP id 4fb4d7f45d1cf-614e7ae014dmr87648a12.6.1753442732938; Fri, 25 Jul 2025 04:25:32 -0700 (PDT) MIME-Version: 1.0 References: <20250724-anonvma-uaf-debug-v1-1-29989ddc4e2a@google.com> <85c4a092-14df-4478-811c-f3789610e4b8@redhat.com> In-Reply-To: From: Jann Horn Date: Fri, 25 Jul 2025 13:24:55 +0200 X-Gm-Features: Ac12FXwcKoerpomFAjOzM4_F9BiaBJ1IxkwRsdKpHovHfzexG6clt04_fcJZefk Message-ID: Subject: Re: [PATCH] mm/rmap: Add anon_vma lifetime debug check To: David Hildenbrand Cc: Andrew Morton , Lorenzo Stoakes , Rik van Riel , "Liam R. Howlett" , Vlastimil Babka , Harry Yoo , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: DDA4C180007 X-Stat-Signature: m4dex7zptp9ojw16zhs4ayqtfp7kwqcw X-HE-Tag: 1753442734-598806 X-HE-Meta: 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 AU5v/m7j B22Jt1UWE/wU7iXhhV7Jq3TZ7tmMVoBWc1EUMtdKnsm804XQ3eZAX95zi5MPYqfUHSyPxK885yeRyCnHoWNgCWUmRvPqZwI3Pla1EcWvoegDhdBhCj7QD6F+OGJshdChggNWLqwXYJtpeBZMMxc5NaDDPzI2F0V2HkN66IUQTI5W0GioGPeqT4btxn9woJa8x/yO/8fAtD2ax3gSt3aAbDWtJkksdHThdxkeYLHUDFXSRiTdQ3hddSxijHaGRCuq0Bml+S35XceBWTBKtiCsbMVgDVUqAa8ohFlZV0kYmddo7IZw= 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, Jul 25, 2025 at 1:12=E2=80=AFPM David Hildenbrand wrote: > On 25.07.25 13:08, Jann Horn wrote: > > On Thu, Jul 24, 2025 at 11:56=E2=80=AFPM David Hildenbrand wrote: > >> 2) We have a folio here, so ... better > >> > >> if (folio_test_anon(folio) && !folio_test_ksm(folio)) { > >> ... > >> } > > > > Hrm, okay. It kind of irks me to write it as two checks when really I > > want to ask "is it this one specific type", but yeah, will change it. > > Well, ksm is a subtype of anon. I mean... not really? At least ksm folios are not a subtype of normal anon folios. Normal anon folios point to an anon_vma, a ksm folio points to a ksm_stable_node instead, and you can't treat a ksm_stable_node as an anon_vma.