Re: [PATCH 6.6 000/389] 6.6.76-rc2 review

[Guenter Roeck <linux@roeck-us.net>]

On 2/6/25 08:06, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 6.6.76 release.
> There are 389 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
> 
> Responses should be made by Sat, 08 Feb 2025 15:51:12 +0000.
> Anything received after that time might be too late.
> 
[ ... ]

> Hongbo Li <lihongbo22@huawei.com>
>      hostfs: fix the host directory parse when mounting.

This patch results in:

Building um:defconfig ... failed
--------------
Error log:
fs/hostfs/hostfs_kern.c:972:9: error: implicit declaration of function 'fsparam_string_empty'; did you mean 'fsparam_string'? [-Werror=implicit-function-declaration]
   972 |         fsparam_string_empty("hostfs",          Opt_hostfs),

because fsparam_string_empty() is not declared globally in v6.6.y.

The patch declaring it is 7b30851a70645 ("fs_parser: move fsparam_string_empty()
helper into header"). Applying that patch on top of 6.6.76 fixes the problem.

The problem only affects "um" builds since hostfs (CONFIG_HOSTFS) is only available
and used there. Oddly enough, the patch breaks the build of this file instead of
fixing the problem it claims to fix, and it looks like no one noticed.
On top of that, "hostfs: convert hostfs to use the new mount API" was obviously
not tested. It looks like a substantial change which would definitely warrant
testing when backported.

That makes me wonder: Should I stop build testing "um" images in older kernels ?

Thanks,
Guenter