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AJvYcCVO5CvXpW6qdrV3Qla5d0gdat5XapVBWOJl++Bf2bgtAzuqJcZy9pDrzHpjWnQYZFFyuWUUg9qUGA==@kvack.org X-Gm-Message-State: AOJu0Yz3Vg71kfcf07wTHaf8Ga2U2n8ieo4vWlkkfCgnLwOhRnENnfvq FLf6zUjwD+JCKSgAwcU7ptNZteRWUGsp35r0XY7IWm8I0pchMf7SD+mehEs8fZGQIMbXOLGph4v 2RswGrbVqOAcscvwwqJqSKdOGHZZDrs9O/Frp9XQb X-Gm-Gg: ASbGncsD6KRU9k52oWI4GQr2Azp/ikuyZ5N4HakNyHIIEJZ81WEOne1I4cVdrPwujIG eE4gFxU7aQVn35pUUqGUFBf53zBbcZLS6LIY8cgiPtKFC7lqwiuNg1wcnsvurT18wIhCcxEOTOu WIkoJho19d+flAv4hBe98aQEduNGVjgXzZEZ0A+jaerc2lUYdYRZFBp2PKKDJYN4sb/4wxkXFJo enzjIkqEbCyAbiMGeotmCCUZF7daIKL/AVxoRjgoRBP2yZUhgAANdsU0xRD8nQ= X-Google-Smtp-Source: AGHT+IGi1Cl1cxLljbDRwITE9vfhwz+DrDPsOJguUQv2zzG51+QwzyCb4weDhywo5yliSwxcW6sHs7Lpaphswpsb2Ak= X-Received: by 2002:a17:902:e550:b0:24c:f4b1:baaf with SMTP id d9443c01a7336-26808a33cc5mr6423875ad.1.1758141109587; Wed, 17 Sep 2025 13:31:49 -0700 (PDT) MIME-Version: 1.0 References: <20250915163838.631445-1-kaleshsingh@google.com> <20250915163838.631445-7-kaleshsingh@google.com> <322fd5d2-d7f4-40d8-8a06-6e7c5e9ef180@redhat.com> In-Reply-To: <322fd5d2-d7f4-40d8-8a06-6e7c5e9ef180@redhat.com> From: Kalesh Singh Date: Wed, 17 Sep 2025 13:31:37 -0700 X-Gm-Features: AS18NWACcEbm1lm4H8WkQEbyfcTpHlrzU-8yyCAEibl_VJPt8WSVNJn2mY9O19Y Message-ID: Subject: Re: [PATCH v2 6/7] mm: add assertion for VMA count limit To: David Hildenbrand Cc: akpm@linux-foundation.org, minchan@kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, pfalcato@suse.de, kernel-team@android.com, android-mm@google.com, Alexander Viro , Christian Brauner , Jan Kara , Kees Cook , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , Jann Horn , Shuah Khan , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: rugay6fmjisxcewq95wri4ng5i5nycna X-Rspam-User: X-Rspamd-Queue-Id: 12A4C2000C X-Rspamd-Server: rspam04 X-HE-Tag: 1758141110-999893 X-HE-Meta: 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 5G3HnIDO E2G+NXXbSEa5JSkvjYrMd6NoSHSMZYBBBdlAfmQ/njMAZwJOjylK+znoC9foDZmPGcKhryTkiegZXk0a5x6kl1tMGuECNFd9t+rezPVu2gGiQfQimLoBdy3LSiRXxl7dTK9ImKz8vhhNoNLm2zbFsnwV1rw/wNVoeEQlLvzR82vVa63+6aKBoS8oc1hgTh7fU2AQzGuH6gy7B+Lkjq4jm3I86DobHKldLm/SCuAHv0Xn7t35KTnyY0FvuSw== 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, Sep 17, 2025 at 11:34=E2=80=AFAM David Hildenbrand wrote: > > >> Can't that fire when changing the max count from user space at just th= e > >> wrong time? > > > > You are right: technically it's possible if it was raised between the > > time of checking and when the new VMA is added. > > > >> > >> I assume we'll have to tolerated that and might just want to drop this > >> patch from the series. > >> > > > > It is compiled out in !CONFIG_VM_DEBUG builds, would we still want to d= rop it? > > Due to the racy nature I think any kinds of assertions would be wrong. > Without any such races possible I would agree that the checks would be > nice to have. Alright I'll drop this in the next revision. Thanks, Kalesh > > -- > Cheers > > David / dhildenb >