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AJvYcCXiFrTDzGhN4uLeP0vh/1tM9zWFG9EuM4nylkaNwiFfn7TQc5MiT4fwlk6b9pe+fnCFAFE4xtkwHA==@kvack.org X-Gm-Message-State: AOJu0YxSHWHGV1J2CHkGwgH9Gu39sehgU/vMvq0nbw4/EsypVtOgVwHv mja6WQuXUhclceUpjzVclZj2uoZWubkQ7X8tvP2vbhUDkcxZ3pQGAfTJqKq9HP0KxhYTpAqKd4C mVeAqtA== X-Received: from dlbps11.prod.google.com ([2002:a05:7023:88b:b0:123:2dd9:db4]) (user=surenb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:e16:b0:11a:342e:8a98 with SMTP id a92af1059eb24-1244b282f14mr3555854c88.0.1768589066553; Fri, 16 Jan 2026 10:44:26 -0800 (PST) Date: Fri, 16 Jan 2026 10:44:23 -0800 Mime-Version: 1.0 X-Mailer: git-send-email 2.52.0.457.g6b5491de43-goog Message-ID: <20260116184423.2708363-1-surenb@google.com> Subject: [PATCH v2 1/1] Docs/mm/allocation-profiling: describe sysctrl limitations in debug mode From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: kent.overstreet@linux.dev, corbet@lwn.net, willy@infradead.org, sj@kernel.org, ranxiaokai627@163.com, ran.xiaokai@zte.com.cn, surenb@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 18A1F120009 X-Rspamd-Server: rspam06 X-Stat-Signature: xnkgz9i8jorsbsot3f5np5qbddw8asox X-Rspam-User: X-HE-Tag: 1768589067-480249 X-HE-Meta: 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 FF2Je8rc 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 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: When CONFIG_MEM_ALLOC_PROFILING_DEBUG=y, /proc/sys/vm/mem_profiling is read-only to avoid debug warnings in a scenario when an allocation is made while profiling is disabled (allocation does not get an allocation tag), then profiling gets enabled and allocation gets freed (warning due to the allocation missing allocation tag). Fixes: ebdf9ad4ca98 ("memprofiling: documentation") Reported-by: Andrew Morton Signed-off-by: Suren Baghdasaryan Acked-by: SeongJae Park Cc: stable@vger.kernel.org --- Based on mm-new Changes since v1 [1]: - Fixed a typo, per Matthew Wilcox - Added Acked-by, per SeongJae Park [1] https://lore.kernel.org/all/20260115054557.2127777-1-surenb@google.com/ Documentation/admin-guide/sysctl/vm.rst | 4 ++++ Documentation/mm/allocation-profiling.rst | 10 ++++++++++ 2 files changed, 14 insertions(+) diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst index 9096e2d77c2a..b98ccb5cb210 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -487,6 +487,10 @@ memory allocations. The default value depends on CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT. +When CONFIG_MEM_ALLOC_PROFILING_DEBUG=y, this control is read-only to avoid +warnings produced by allocations made while profiling is disabled and freed +when it's enabled. + memory_failure_early_kill ========================= diff --git a/Documentation/mm/allocation-profiling.rst b/Documentation/mm/allocation-profiling.rst index 316311240e6a..5389d241176a 100644 --- a/Documentation/mm/allocation-profiling.rst +++ b/Documentation/mm/allocation-profiling.rst @@ -33,6 +33,16 @@ Boot parameter: sysctl: /proc/sys/vm/mem_profiling + 1: Enable memory profiling. + + 0: Disable memory profiling. + + The default value depends on CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT. + + When CONFIG_MEM_ALLOC_PROFILING_DEBUG=y, this control is read-only to avoid + warnings produced by allocations made while profiling is disabled and freed + when it's enabled. + Runtime info: /proc/allocinfo base-commit: eeb33083cc4749bdb61582eaeb5c200702607703 -- 2.52.0.457.g6b5491de43-goog