From b42bc9a3c5115c3102a4923776bbeed3b191f2db Mon Sep 17 00:00:00 2001
From: Domenico Andreoli <domenico.andreoli@linux.com>
Date: Wed, 9 Feb 2022 08:49:20 +0100
Subject: [PATCH] Fix regression due to "fs: move binfmt_misc sysctl to its own
file"
Commit 3ba442d5331f ("fs: move binfmt_misc sysctl to its own file") did
not go unnoticed, binfmt-support stopped to work on my Debian system
since v5.17-rc2 (did not check with -rc1).
The existance of the /proc/sys/fs/binfmt_misc is a precondition for
attempting to mount the binfmt_misc fs, which in turn triggers the
autoload of the binfmt_misc module. Without it, no module is loaded and
no binfmt is available at boot.
Building as built-in or manually loading the module and mounting the fs
works fine, it's therefore only a matter of interaction with user-space.
I could try to improve the Debian systemd configuration but I can't say
anything about the other distributions.
This patch restores a working system right after boot.
Fixes: 3ba442d5331f ("fs: move binfmt_misc sysctl to its own file")
Signed-off-by: Domenico Andreoli <domenico.andreoli@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Tong Zhang <ztong0001@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/binfmt_misc.c | 6 +-----
fs/file_table.c | 2 ++
2 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index c07f35719ee3..e1eae7ea823a 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -817,20 +817,16 @@ static struct file_system_type bm_fs_type = {
};
MODULE_ALIAS_FS("binfmt_misc");
-static struct ctl_table_header *binfmt_misc_header;
-
static int __init init_misc_binfmt(void)
{
int err = register_filesystem(&bm_fs_type);
if (!err)
insert_binfmt(&misc_format);
- binfmt_misc_header = register_sysctl_mount_point("fs/binfmt_misc");
- return 0;
+ return err;
}
static void __exit exit_misc_binfmt(void)
{
- unregister_sysctl_table(binfmt_misc_header);
unregister_binfmt(&misc_format);
unregister_filesystem(&bm_fs_type);
}
diff --git a/fs/file_table.c b/fs/file_table.c
index 57edef16dce4..4969021fa676 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -119,6 +119,8 @@ static struct ctl_table fs_stat_sysctls[] = {
static int __init init_fs_stat_sysctls(void)
{
register_sysctl_init("fs", fs_stat_sysctls);
+ if (IS_ENABLED(CONFIG_BINFMT_MISC))
+ register_sysctl_mount_point("fs/binfmt_misc");
return 0;
}
fs_initcall(init_fs_stat_sysctls);
--
2.42.0