[merged mm-hotfixes-stable] proc-proc_maps_open-allow-proc_mem_open-to-return-null.patch removed from -mm tree

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

The quilt patch titled
     Subject: proc: proc_maps_open allow proc_mem_open to return NULL
has been removed from the -mm tree.  Its filename was
     proc-proc_maps_open-allow-proc_mem_open-to-return-null.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Jialin Wang <wjl.linux@gmail.com>
Subject: proc: proc_maps_open allow proc_mem_open to return NULL
Date: Fri, 8 Aug 2025 00:54:55 +0800

The commit 65c66047259f ("proc: fix the issue of proc_mem_open returning
NULL") caused proc_maps_open() to return -ESRCH when proc_mem_open()
returns NULL.  This breaks legitimate /proc/<pid>/maps access for kernel
threads since kernel threads have NULL mm_struct.

The regression causes perf to fail and exit when profiling a kernel
thread:

  # perf record -v -g -p $(pgrep kswapd0)
  ...
  couldn't open /proc/65/task/65/maps

This patch partially reverts the commit to fix it.

Link: https://lkml.kernel.org/r/20250807165455.73656-1-wjl.linux@gmail.com
Fixes: 65c66047259f ("proc: fix the issue of proc_mem_open returning NULL")
Signed-off-by: Jialin Wang <wjl.linux@gmail.com>
Cc: Penglei Jiang <superman.xpt@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/proc/task_mmu.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/proc/task_mmu.c~proc-proc_maps_open-allow-proc_mem_open-to-return-null
+++ a/fs/proc/task_mmu.c
@@ -340,8 +340,8 @@ static int proc_maps_open(struct inode *
 
 	priv->inode = inode;
 	priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
-	if (IS_ERR_OR_NULL(priv->mm)) {
-		int err = priv->mm ? PTR_ERR(priv->mm) : -ESRCH;
+	if (IS_ERR(priv->mm)) {
+		int err = PTR_ERR(priv->mm);
 
 		seq_release_private(inode, file);
 		return err;
_

Patches currently in -mm which might be from wjl.linux@gmail.com are