quoted

From 4c6b4d4cb08aee9559d02a348b9ecf799142c96f Mon Sep 17 00:00:00 2001
From: Brendan Jackman <jackmanb@google.com>
Date: Wed, 17 Dec 2025 13:26:28 +0000
Subject: [PATCH] mm: clarify GFP_ATOMIC/GFP_NOWAIT doc-comment

The current description of contexts where it's invalid to make
GFP_ATOMIC and GFP_NOWAIT calls is rather vague.

Replace this with a direct description of the actual contexts of concern
and refer to the RT docs where this is explained more discursively.

While rejigging this prose, also move the documentation of GFP_NOWAIT to
the GFP_NOWAIT section.

There doesn't seem to be any move?

This is referring to [0] and [1].

quoted

diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
index 3de43b12209ee..07a378542caf2 100644
--- a/include/linux/gfp_types.h
+++ b/include/linux/gfp_types.h

@@ -309,8 +309,10 @@ enum {
  *
  * %GFP_ATOMIC users can not sleep and need the allocation to succeed. A lower
  * watermark is applied to allow access to "atomic reserves".
- * The current implementation doesn't support NMI and few other strict
- * non-preemptive contexts (e.g. raw_spin_lock). The same applies to %GFP_NOWAIT.

[0]                                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^

quoted

+ * The current implementation doesn't support NMI, nor contexts that disable
+ * preemption under PREEMPT_RT. This includes raw_spin_lock() and plain
+ * preempt_disable() - see Documentation/core-api/real-time/differences.rst for
+ * more info.

Can we reference the "Memory allocation" section directly?

Yeah good point. I will send this as a standalone [PATCH] mail tomorrow.

quoted

  *
  * %GFP_KERNEL is typical for kernel-internal allocations. The caller requires
  * %ZONE_NORMAL or a lower zone for direct access but can direct reclaim.

@@ -321,6 +323,7 @@ enum {
  * %GFP_NOWAIT is for kernel allocations that should not stall for direct
  * reclaim, start physical IO or use any filesystem callback.  It is very
  * likely to fail to allocate memory, even for very small allocations.
+ * The same restrictions on calling contexts apply as for %GFP_ATOMIC.

[1]     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^