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

[PATCH 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>
Cc: stable@vger.kernel.org
---
 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..8577ea91e226 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 produces 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..058d2faffb75 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 produces by allocations made while profiling is disabled and freed
+  when it's enabled.
+
 Runtime info:
   /proc/allocinfo
 

base-commit: 560d6a4c4951ae76b5c6d5b5b8650276706f68ac
-- 
2.52.0.457.g6b5491de43-goog

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

[Matthew Wilcox]

On Wed, Jan 14, 2026 at 09:45:57PM -0800, Suren Baghdasaryan wrote:
> +  warnings produces by allocations made while profiling is disabled and freed

"produced"

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

[Suren Baghdasaryan]

On Wed, Jan 14, 2026 at 9:57 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Wed, Jan 14, 2026 at 09:45:57PM -0800, Suren Baghdasaryan wrote:
> > +  warnings produces by allocations made while profiling is disabled and freed
>
> "produced"

Thanks! I'll wait for a day and if there are no other objections, I
will post a fixed version.

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

[SeongJae Park]

On Thu, 15 Jan 2026 09:05:25 -0800 Suren Baghdasaryan <surenb@google.com> wrote:

> On Wed, Jan 14, 2026 at 9:57 PM Matthew Wilcox <willy@infradead.org> wrote:
> >
> > On Wed, Jan 14, 2026 at 09:45:57PM -0800, Suren Baghdasaryan wrote:
> > > +  warnings produces by allocations made while profiling is disabled and freed
> >
> > "produced"
> 
> Thanks! I'll wait for a day and if there are no other objections, I
> will post a fixed version.

Assuming Matthiew's good finding will be fixed,

Acked-by: SeongJae Park <sj@kernel.org>

Fwiw, the typo is also on the .../sysctl/vm.rst part.  And from the finding, I
was wondering if it is better to put the description only one of two documents
rather than having the duplication, and further if the 'Usage:' part of
allocation-profiling.rst is better to be moved to
'Documentation/admin-guide/mm/'.  But I ended up thinking those are too trivial
and small things.


Thanks,
SJ

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

[Suren Baghdasaryan]

On Thu, Jan 15, 2026 at 6:18 PM SeongJae Park <sj@kernel.org> wrote:
>
> On Thu, 15 Jan 2026 09:05:25 -0800 Suren Baghdasaryan <surenb@google.com> wrote:
>
> > On Wed, Jan 14, 2026 at 9:57 PM Matthew Wilcox <willy@infradead.org> wrote:
> > >
> > > On Wed, Jan 14, 2026 at 09:45:57PM -0800, Suren Baghdasaryan wrote:
> > > > +  warnings produces by allocations made while profiling is disabled and freed
> > >
> > > "produced"
> >
> > Thanks! I'll wait for a day and if there are no other objections, I
> > will post a fixed version.
>
> Assuming Matthiew's good finding will be fixed,
>
> Acked-by: SeongJae Park <sj@kernel.org>

Thanks!

>
> Fwiw, the typo is also on the .../sysctl/vm.rst part.

Correct, I'll fix in both places.

> And from the finding, I
> was wondering if it is better to put the description only one of two documents
> rather than having the duplication, and further if the 'Usage:' part of
> allocation-profiling.rst is better to be moved to
> 'Documentation/admin-guide/mm/'.  But I ended up thinking those are too trivial
> and small things.

Yes, I didn't want to complicate reader's life by adding a reference
for a couple of sentences.

>
>
> Thanks,
> SJ

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

[Suren Baghdasaryan]

On Fri, Jan 16, 2026 at 10:30 AM Suren Baghdasaryan <surenb@google.com> wrote:
>
> On Thu, Jan 15, 2026 at 6:18 PM SeongJae Park <sj@kernel.org> wrote:
> >
> > On Thu, 15 Jan 2026 09:05:25 -0800 Suren Baghdasaryan <surenb@google.com> wrote:
> >
> > > On Wed, Jan 14, 2026 at 9:57 PM Matthew Wilcox <willy@infradead.org> wrote:
> > > >
> > > > On Wed, Jan 14, 2026 at 09:45:57PM -0800, Suren Baghdasaryan wrote:
> > > > > +  warnings produces by allocations made while profiling is disabled and freed
> > > >
> > > > "produced"
> > >
> > > Thanks! I'll wait for a day and if there are no other objections, I
> > > will post a fixed version.
> >
> > Assuming Matthiew's good finding will be fixed,
> >
> > Acked-by: SeongJae Park <sj@kernel.org>
>
> Thanks!
>
> >
> > Fwiw, the typo is also on the .../sysctl/vm.rst part.
>
> Correct, I'll fix in both places.

v2 is posted at
https://lore.kernel.org/all/20260116184423.2708363-1-surenb@google.com/

>
> > And from the finding, I
> > was wondering if it is better to put the description only one of two documents
> > rather than having the duplication, and further if the 'Usage:' part of
> > allocation-profiling.rst is better to be moved to
> > 'Documentation/admin-guide/mm/'.  But I ended up thinking those are too trivial
> > and small things.
>
> Yes, I didn't want to complicate reader's life by adding a reference
> for a couple of sentences.
>
> >
> >
> > Thanks,
> > SJ