Re: [PATCH 5.4 00/90] 5.4.263-rc3 review

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Dec 08, 2023 at 10:09:17AM -0800, Guenter Roeck wrote:
> On 12/5/23 11:22, Greg Kroah-Hartman wrote:
> > This is the start of the stable review cycle for the 5.4.263 release.
> > There are 90 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 Thu, 07 Dec 2023 18:32:16 +0000.
> > Anything received after that time might be too late.
> > 
> [ ... ]
> > Qu Wenruo <wqu@suse.com>
> >      btrfs: add dmesg output for first mount and last unmount of a filesystem
> > 
> 
> This patch results in the following code in fs/btrfs/disk-io.c:open_ctree():
> 
> 	struct btrfs_super_block *disk_super;
> 	... (no access to disk_super)
> 	btrfs_info(fs_info, "first mount of filesystem %pU", disk_super->fsid);
> 
> which I would assume _should_ result in btrfs crashes. No idea why that isn't
> actually happening or why gcc doesn't complain. Building allmodconfig with
> clang does complain, but doesn't bail out.
> 
> s/btrfs/disk-io.c:2832:55: warning: variable 'disk_super' is uninitialized when used here [-Wuninitialized]
>         btrfs_info(fs_info, "first mount of filesystem %pU", disk_super->fsid);
>                                                              ^~~~~~~~~~
> 
> The actual log output is:
> 
> [    7.302427] BTRFS info (device nvme0n1): first mount of filesystem (efault)
> 
> It might be a good idea to either revert this patch or fix it up
> (though I don't know how to fix it up).

yeah, that doesn't look good, now reverted, thanks!

greg k-h