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AJvYcCX875HiyBi3lJNo/5Mtn7o1RnDbwir6hkkyC7V7CN2xLzTxsktqpW3aagphOcMjHurD61BhCcsO9w==@kvack.org X-Gm-Message-State: AOJu0Yybv8LPbGUUNeknxGnj6c/+flm2Ks/tf6kolKeZvnZIIqDE4pnA MbzkL3haEnLklB5+ifZMEGnlkSAUXB+VLnLCJyjIZIvAZoQapflzVPpxAcBydySOwN71VvmEu/X CJaHLkvWBpi2Okuncr2EsyoO26MfiZlmoHboJvyzB X-Gm-Gg: ASbGncu6EVaC8rAQK4lkrp0ch04YTYtuXdYMc7cUmJ1cn269mg3siGbc6kjexSuiNot Q/FUnGrOZRm6bpnd/NmyYvhyylk7UBoWUrbDRLBTWNui402rxrBdL3KQ0+vP+2n/iwBVuQSj6GV cYQW5e1nzX/iKfV5Fr89ao7VwKsalDFcQ8THC5ycEnBw1AUfJz9cd9NgUlrEyHxmkaUal2sOgTj 8UF0O/qEhp3zB5YiZ+/4FBnjgnLeYt2XZAoWGdxxzPkp9HhNKhL3EE= X-Google-Smtp-Source: AGHT+IEkitpGEz8BMKWmLGPZ3W85vqrSP9MG29lIbMnJb9upndiATYfQPV08S+weYTCqY9YvT87o5wWIohG6pp/8rq4= X-Received: by 2002:a17:903:181:b0:246:a8ac:1a36 with SMTP id d9443c01a7336-267c1903062mr2169965ad.2.1757977867063; Mon, 15 Sep 2025 16:11:07 -0700 (PDT) MIME-Version: 1.0 References: <20250915163838.631445-1-kaleshsingh@google.com> <20250915153401.61cbd5120871ee7a4e5b9cae@linux-foundation.org> In-Reply-To: <20250915153401.61cbd5120871ee7a4e5b9cae@linux-foundation.org> From: Kalesh Singh Date: Mon, 15 Sep 2025 16:10:55 -0700 X-Gm-Features: Ac12FXwVYGcBZT9d6NPCct-EK04uGWSzFyRbMpRKe55ZXQp9Zltcw49n-TJl9YM Message-ID: Subject: Re: [PATCH v2 0/7] vma count: fixes, test and improvements To: Andrew Morton Cc: minchan@kernel.org, lorenzo.stoakes@oracle.com, david@redhat.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-Rspamd-Queue-Id: 8E652140006 X-Stat-Signature: qy3x1du7ohrn7sioxfrpxrkkc1fx587d X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1757977868-651589 X-HE-Meta: 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 NX9V/cBn Xp4Y/OWuk4LPP9ZB9AvENC/7ULzpxklOndzb+Q3Z7FcRbEnZ1i/KIBbBElOWcpl+O8qZ4Ci52/Zrvm10NTiStGKQkgtPQ3loBQD9p/rdpt0KAfUX8YMCxB9AsVl+rOlGUrCBRxaQZyPIc+4jKExUeARzUPMQfKXxn1ROIwNCkDys4AQsUQx8Lr2gfYNzYZLs3ffEafrVB6x4EhDcgW/iELBd1Q+SmgEjW6Hp2gXbuQxVPXFpACDmFjGT1NMfCo1mR/hqBWYNEu96eJdGivizQoQSn4U1HaWDCE5KK9KmPxLapKdE= 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 Mon, Sep 15, 2025 at 3:34=E2=80=AFPM Andrew Morton wrote: > > On Mon, 15 Sep 2025 09:36:31 -0700 Kalesh Singh = wrote: > > > Hi all, > > > > This is v2 to the VMA count patch I previously posted at: > > > > https://lore.kernel.org/r/20250903232437.1454293-1-kaleshsingh@google.c= om/ > > > > > > I've split it into multiple patches to address the feedback. > > > > The main changes in v2 are: > > > > - Use a capacity-based check for VMA count limit, per Lorenzo. > > - Rename map_count to vma_count, per David. > > - Add assertions for exceeding the limit, per Pedro. > > - Add tests for max_vma_count, per Liam. > > - Emit a trace event for failure due to insufficient capacity for > > observability > > > > Tested on x86_64 and arm64: > > > > - Build test: > > - allyesconfig for rename > > > > - Selftests: > > cd tools/testing/selftests/mm && \ > > make && \ > > ./run_vmtests.sh -t max_vma_count > > > > (With trace_max_vma_count_exceeded enabled) > > > > - vma tests: > > cd tools/testing/vma && \ > > make && \ > > ./vma > > fwiw, there's nothing in the above which is usable in a [0/N] overview. > > While useful, the "what changed since the previous version" info isn't > a suitable thing to carry in the permanent kernel record - it's > short-term treansient stuff, not helpful to someone who is looking at > the patchset in 2029. > > Similarly, the "how it was tested" material is also useful, but it > becomes irrelevant as soon as the code hits linux-next and mainline. Hi Andrew, Thanks for the feedback. Do you mean the cover letter was not needed in this case or that it lacked enough context? > > > Anyhow, this -rc cycle has been quite the firehose in MM and I'm > feeling a need to slow things down for additional stabilization and so > people hopefully get additional bandwidth to digest the material we've > added this far. So I think I'll just cherrypick [1/7] for now. A > great flood of positive review activity would probably make me revisit > that ;) > I understand, yes 1/7 is all we need for now, since it prevents an unrecoverable situation where we get over the limit and cannot recover as munmap() will then always fail. Thanks, Kalesh