Re: [PATCH v8 16/19] fsnotify: generate pre-content permission event on page fault

Jan Kara
2024-12-09T12:31:41Z

Hello!

On Sun 08-12-24 17:58:42, Klara Modin wrote:
> On 2024-11-15 16:30, Josef Bacik wrote:
> > FS_PRE_ACCESS or FS_PRE_MODIFY will be generated on page fault depending
> > on the faulting method.
> >
> > This pre-content event is meant to be used by hierarchical storage
> > managers that want to fill in the file content on first read access.
> >
> > Export a simple helper that file systems that have their own ->fault()
> > will use, and have a more complicated helper to be do fancy things with
> > in filemap_fault.
> >
>
> This patch (0790303ec869d0fd658a548551972b51ced7390c in next-20241206)
> interacts poorly with some programs which hang and are stuck at 100 % sys
> cpu usage (examples of programs are logrotate and atop with root
> privileges).
>
> I also retested the new version on Jan Kara's for_next branch and it behaves
> the same way.

Thanks for report! What is your kernel config please? I've just fixed a
bug reported by [1] which manifested in the same way with
CONFIG_FANOTIFY_ACCESS_PERMISSIONS=n.

Can you perhaps test with my for_next branch I've just pushed out? Thanks!

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR