+ dyndbg-fix-incorrect-mod_ct-value-in-dynamic_debug_init.patch added to mm-nonmm-unstable branch

+ dyndbg-fix-incorrect-mod_ct-value-in-dynamic_debug_init.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: dyndbg: fix incorrect mod_ct value in dynamic_debug_init()
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     dyndbg-fix-incorrect-mod_ct-value-in-dynamic_debug_init.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/dyndbg-fix-incorrect-mod_ct-value-in-dynamic_debug_init.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Yuntao Wang <yuntao.wang@linux.dev>
Subject: dyndbg: fix incorrect mod_ct value in dynamic_debug_init()
Date: Tue, 11 Aug 2026 20:18:30 +0800

Patch series "dyndbg: fix incorrect mod_ct value in dynamic_debug_init()".

Fix and clean up dynamic_debug_init().


This patch (of 2):

Suppose all `struct _ddebug` instances belong to the same module, mod_ct
should be 1, but it is currently 0.

mod_ct is incremented only when iter->modname changes, i.e.  when the loop
encounters the first _ddebug entry of a new module:

if (strcmp(modname, iter->modname)) {
	mod_ct++;
	...
}

If all _ddebug entries belong to the same module, strcmp() never returns
nonzero, so mod_ct remains 0.

However, the last (and in this case only) module is added after the loop:

di.num_descs = mod_sites;
di.descs = iter_mod_start;
ret = ddebug_add_module(&di, modname);

Thus, mod_ct should be incremented before adding this final module.

The bug only affects the diagnostic message printed by vpr_info():

"%d prdebugs in %d modules, ..."

It reports one fewer module than the actual number of modules.  There is
no userspace-visible runtime effect; the dynamic debug tables themselves
are initialized correctly.

Fix it.
		
Link: https://lore.kernel.org/20260811121831.577848-1-yuntao.wang@linux.dev
Link: https://lore.kernel.org/20260811121831.577848-2-yuntao.wang@linux.dev
Signed-off-by: Yuntao Wang <yuntao.wang@linux.dev>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/dynamic_debug.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/lib/dynamic_debug.c~dyndbg-fix-incorrect-mod_ct-value-in-dynamic_debug_init
+++ a/lib/dynamic_debug.c
@@ -1456,6 +1456,8 @@ static int __init dynamic_debug_init(voi
 			iter_mod_start = iter;
 		}
 	}
+
+	mod_ct++;
 	di.num_descs = mod_sites;
 	di.descs = iter_mod_start;
 	ret = ddebug_add_module(&di, modname);
_

Patches currently in -mm which might be from yuntao.wang@linux.dev are

dyndbg-fix-incorrect-mod_ct-value-in-dynamic_debug_init.patch
dyndbg-clean-up-dynamic_debug_init-to-improve-readability.patch