From b42bc9a3c5115c3102a4923776bbeed3b191f2db Mon Sep 17 00:00:00 2001 From: Domenico Andreoli 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 Cc: Andrew Morton Cc: Luis Chamberlain Reviewed-by: Tong Zhang Signed-off-by: Linus Torvalds --- 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);