From: Arnd Bergmann <arnd@arndb.de>

This symbol can now be used from a loadable erofs module, which causes
a build failure when it is not exported:

ERROR: modpost: "security_mmap_backing_file" [fs/erofs/erofs.ko] undefined!

Fixes: 0e2baaf8fed0 ("lsm: add the security_mmap_backing_file() hook")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 security/security.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/security/security.c b/security/security.c
index 8d10b184ce25..3e426a762864 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2529,6 +2529,7 @@ int security_mmap_backing_file(struct vm_area_struct *vma,
 
 	return call_int_hook(mmap_backing_file, vma, backing_file, user_file);
 }
+EXPORT_SYMBOL_GPL(security_mmap_backing_file);
 
 /**
  * security_mmap_addr() - Check if mmap'ing an address is allowed
-- 
2.39.5

On Wed, Mar 18, 2026 at 6:43 AM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> This symbol can now be used from a loadable erofs module, which causes
> a build failure when it is not exported:
>
> ERROR: modpost: "security_mmap_backing_file" [fs/erofs/erofs.ko] undefined!
>
> Fixes: 0e2baaf8fed0 ("lsm: add the security_mmap_backing_file() hook")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  security/security.c | 1 +
>  1 file changed, 1 insertion(+)

Thanks Arnd.  It looks like I'm going to need to respin this patchset
due to other changes, do you mind if I fold this patch into the
associated LSM patch when I do that, or would you prefer this as a
standalone fix?  No worries either way, fixes are always appreciated
:)

> diff --git a/security/security.c b/security/security.c
> index 8d10b184ce25..3e426a762864 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2529,6 +2529,7 @@ int security_mmap_backing_file(struct vm_area_struct *vma,
>
>         return call_int_hook(mmap_backing_file, vma, backing_file, user_file);
>  }
> +EXPORT_SYMBOL_GPL(security_mmap_backing_file);
>
>  /**
>   * security_mmap_addr() - Check if mmap'ing an address is allowed
> --
> 2.39.5

-- 
paul-moore.com