Re: [PATCH 2/2] vfs: Fix anon_inode triggering VFS_BUG_ON_INODE in may_open()

[Christoph Hellwig]

On Fri, Apr 04, 2025 at 10:45:43AM +0200, Christian Brauner wrote:
> On Fri, Apr 04, 2025 at 01:31:58AM -0700, Christoph Hellwig wrote:
> > Please make sure anon inodes have a valid mode set.  Leaving this
> > landmine around where we have inodes without a valid mode is just going
> > to create more problems in the future.
> 
> We've tried to change it, it immediately leads to userspace tools
> regressions as they've started to rely on that behavior because it's been
> like that since the dawn of time. We even had to work around that crap
> in pidfs because lsof regressed. So now, we can't do this.

Just because i_mode has something useful, we don't need to report that
to userspace.  We can still clear kstat.mode (with a big fat comment
explaining why).