On Fri, 31 Jan 2025 at 11:17, Alex Williamson
<alex.williamson@xxxxxxxxxx> wrote:
>
> 20bf82a898b6 ("mm: don't allow huge faults for files with pre content watches")
>
> This breaks huge_fault support for PFNMAPs that was recently added in
> v6.12 and is used by vfio-pci to fault device memory using PMD and PUD
> order mappings.
Surely only for content watches?
Which shouldn't be a valid situation *anyway*.
IOW, there must be some unrelated bug somewhere: either somebody is
allowed to set a pre-content match on a special device.
That should be disabled by the whole
/*
* If there are permission event watchers but no pre-content event
* watchers, set FMODE_NONOTIFY | FMODE_NONOTIFY_PERM to indicate that.
*/
thing in file_set_fsnotify_mode() which only allows regular files and
directories to be notified on.
Or, alternatively, that check for huge-fault disabling is just
checking the wrong bits.
Or - quite possibly - I am missing something obvious?
Linus
