From cb7d761bf5d4b1600564efdd42653b821eb2ec8e Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Fri, 16 Jan 2026 10:44:23 -0800 Subject: [PATCH] Docs/mm/allocation-profiling: describe sysctrl limitations in debug mode 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). Link: https://lkml.kernel.org/r/20260116184423.2708363-1-surenb@google.com Fixes: ebdf9ad4ca98 ("memprofiling: documentation") Reported-by: Andrew Morton Signed-off-by: Suren Baghdasaryan Acked-by: SeongJae Park Cc: Jonathan Corbet Cc: Kent Overstreet Cc: Matthew Wilcox (Oracle) Cc: Ran Xiaokai Cc: SeongJae Park Signed-off-by: Andrew Morton --- 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 4d71211fdad8..245bf6394935 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -494,6 +494,10 @@ 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 -- 2.47.3