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Wed, 27 Aug 2025 23:12:49 -0700 (PDT) MIME-Version: 1.0 References: <20250826071948.2618-1-laoar.shao@gmail.com> <20250826071948.2618-5-laoar.shao@gmail.com> In-Reply-To: From: Yafang Shao Date: Thu, 28 Aug 2025 14:12:12 +0800 X-Gm-Features: Ac12FXwA8AE2T9DT0lZOOileufyZaAaDfXMTycJckIK5rbkI3PvbmFzzlT8sNXM Message-ID: Subject: Re: [PATCH v6 mm-new 04/10] bpf: mark vma->vm_mm as trusted To: Lorenzo Stoakes Cc: akpm@linux-foundation.org, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, hannes@cmpxchg.org, usamaarif642@gmail.com, gutierrez.asier@huawei-partners.com, willy@infradead.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, ameryhung@gmail.com, rientjes@google.com, corbet@lwn.net, bpf@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 386B5140003 X-Stat-Signature: b334swhz8jijptfbama1zzjkdedaukyi X-Rspam-User: X-HE-Tag: 1756361570-119024 X-HE-Meta: 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 AhJmoY6I lHM8JAF0yC4+BCFywlhX8fTR137bwdrYvf7vZbaz2YgCkgems8lKQDS+PuVbU54wywV62Tvn+oYlMiFll79gccxfvSN6IfUoV1bla 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 27, 2025 at 11:46=E2=80=AFPM Lorenzo Stoakes wrote: > > On Tue, Aug 26, 2025 at 03:19:42PM +0800, Yafang Shao wrote: > > Every VMA must have an associated mm_struct, and it is safe to access > > Err this isn't true? Pretty sure special VMAs don't have that set. I=E2=80=99m not aware of any VMA that doesn=E2=80=99t belong to an mm_struc= t. If there is such a case, it would be helpful if you could point it out. In any case, I=E2=80=99ll remove the VMA-related code in the next version since it= =E2=80=99s unnecessary. > > > outside of RCU. Thus, we can mark it as trusted. With this change, BPF > > helpers can safely access vma->vm_mm to retrieve the associated task > > from the VMA. > > On the basis of above don't think this is valid. > --=20 Regards Yafang