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Thu, 28 Aug 2025 20:05:37 -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: Fri, 29 Aug 2025 11:05:01 +0800 X-Gm-Features: Ac12FXyRkVAu3IBFWqROm107KDRmxs-OaNCft6vWe5MQxiSekVcD1hUUDL-ITVU 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: rspam07 X-Rspamd-Queue-Id: 008D2C0007 X-Stat-Signature: wzuh5jb9wxxusjyfegjewae89tk8rmhx X-Rspam-User: X-HE-Tag: 1756436738-29346 X-HE-Meta: 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 cBG0ezz8 Wz1Kbd7GXaz23P52Rk7hY20EYQOySn0iEdSIEvgZwJGjvREwx/X5/2ZBZzEuz6wpgytdpqSZo+YfQKEej+LgECSDJg3j7zt9Q8jBRhhYHUAAa8fTx/kQ3woyWf/EfrEn/BqZHXiftuOMFv7JbCYOCa0PnS8EUBc/Gb2vVWLkGtJxKnqPK7KCjNXmIr6XzcJMeADG4tDaQNMp4APZpGY3yLxu2yD2C3XK4dTKF6+m/V/wQHdySfHM9N1VwAI8Wz2jHB0gKrxV7BXgGB0PKGhcHukaJcvvw2oCcjVocnbg+U3s9jQAUJobCi9jux1AD67WZz7KirLVALqadJvsA5eRYoiwhsRUGMpY4rGwEKgIBiGPTZes2y60BNX3kI07AGf3hOUFj7P6jgxcsFz4TG8157bcM4jPdIL9Hs8A079XwfeCgPzgyXAtOtwKwAmccT9dpYUbYFt5QPnUSZU8= 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 Thu, Aug 28, 2025 at 7:11=E2=80=AFPM Lorenzo Stoakes wrote: > > On Thu, Aug 28, 2025 at 02:12:12PM +0800, Yafang Shao wrote: > > 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 acce= ss > > > > > > 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_s= truct. 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 sinc= e it=E2=80=99s > > unnecessary. > > If you lok at get_vma_name() in fs/proc/task_mmu.c you'll see: > > if (!vma->vm_mm) { > *name =3D "[vdso]"; > return; > } > > So a VDSO will have this condition. > > I did a quick drgn()/printk() test and didn't see any, but maybe my syste= m - but > in any case this appears to be a valid situation that can arise, presumab= ly > because it's a VMA somehow shared with multiple mm's or something truly g= od > awful like that :) Thanks for clarifying that. --=20 Regards Yafang