[PATCH v2 1/1] Docs/mm/allocation-profiling: describe sysctrl limitations in debug mode

[PATCH v2 1/1] Docs/mm/allocation-profiling: describe sysctrl limitations in debug mode

[Suren Baghdasaryan]

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 <akpm@linux-foundation.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: SeongJae Park <sj@kernel.org>
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

Re: [PATCH v2 1/1] Docs/mm/allocation-profiling: describe sysctrl limitations in debug mode

[Andrew Morton]

On Fri, 16 Jan 2026 10:44:23 -0800 Suren Baghdasaryan <surenb@google.com> wrote:

> 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).

Cool, thanks.

> Cc: stable@vger.kernel.org

Documentation/process/stable-kernel-rules.rst tells me that -stable tree
users prefer incorrect documentation ;)