[to-be-updated] alloc_tag-fix-undetected-compressed-tag-overflow-when-profiling-is-disabled.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: alloc_tag: fix undetected compressed tag overflow when profiling is disabled
has been removed from the -mm tree.  Its filename was
     alloc_tag-fix-undetected-compressed-tag-overflow-when-profiling-is-disabled.patch

This patch was dropped because an updated version will be issued

------------------------------------------------------
From: Hao Ge <hao.ge@linux.dev>
Subject: alloc_tag: fix undetected compressed tag overflow when profiling is disabled
Date: Wed, 5 Aug 2026 17:06:33 +0800

In reserve_module_tags(), the tag overflow check is gated on
mem_alloc_profiling_enabled():

    if (mem_alloc_profiling_enabled() && !tags_addressable())

If profiling is toggled off at runtime and a module is loaded whose tags
exceed the compressed-mode limit, shutdown_mem_profiling() is skipped. 
vm_module_tags_populate() still maps memory for the tags and the module
loads successfully, but the total tag count now exceeds what
NR_UNUSED_PAGEFLAG_BITS can address.

Once profiling is re-enabled, ref_to_idx() computes each tag's index as
its position in the alloc_tag array.  update_page_tag_ref() masks it to
alloc_tag_ref_mask before storing in page->flags.  Indices beyond the mask
are truncated and idx_to_ref() resolves them to wrong tags.

This silently corrupts /proc/allocinfo: allocated pages get attributed to
the wrong call sites, so the statistics it reports are wrong.

mem_alloc_profiling_enabled() and mem_profiling_compressed are
independent.  Once compressed mode is established at boot, it stays active
regardless of runtime toggles of mem_profiling.

Remove the mem_alloc_profiling_enabled() guard.  Also return an error
after shutdown_mem_profiling() to skip vm_module_tags_populate(), as the
mapped pages would never be reused - shutdown_mem_profiling() sets
mem_profiling_support to false, so no future module load enters the
codetag path.

Link: https://lore.kernel.org/20260805090633.141001-1-hao.ge@linux.dev
Fixes: 4835f747d3ed ("alloc_tag: support for page allocation tag compression")
Signed-off-by: Hao Ge <hao.ge@linux.dev>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/alloc_tag.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/mm/alloc_tag.c~alloc_tag-fix-undetected-compressed-tag-overflow-when-profiling-is-disabled
+++ a/mm/alloc_tag.c
@@ -904,10 +904,11 @@ unlock:
 		int grow_res;
 
 		module_tags.size = offset + size;
-		if (mem_alloc_profiling_enabled() && !tags_addressable()) {
+		if (!tags_addressable()) {
 			shutdown_mem_profiling(true);
-			pr_warn("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n",
-				mod->name, NR_UNUSED_PAGEFLAG_BITS);
+			pr_warn_once("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n",
+				     mod->name, NR_UNUSED_PAGEFLAG_BITS);
+			return ERR_PTR(-ENOMEM);
 		}
 
 		grow_res = vm_module_tags_populate();
_

Patches currently in -mm which might be from hao.ge@linux.dev are