[PATCH v3 0/6] Fix for potential deadlock in pre-content event

[Amir Goldstein <amir73il@gmail.com>]

Jan,

This is the mmap solution proposed by Josef to solve the potential
deadlock with faulting in user pages [1].

I've added test coverage to mmap() pre-content events and verified
no pre-content events on page fault [2].

After some push back on [v2] for disabling page fault pre-content hooks
while leaving their code in the kernel, this series revert the page
fault pre-content hooks.

This leaves DAX files access without pre-content hooks, but that was
never a goal for this feature, so I think that is fine.

Thanks,
Amir.

Changes since v2:
- Revert page fault pre-content hooks
- Remove mmap hook from remap_file_pages() (Lorenzo)
- Create fsnotify_mmap_perm() wrapper (Lorenzo)

[1] https://lore.kernel.org/linux-fsdevel/20250307154614.GA59451@perftesting/
[2] https://github.com/amir73il/ltp/commits/fan_hsm/
[v2] https://lore.kernel.org/linux-fsdevel/20250311114153.1763176-1-amir73il@gmail.com/
[v1] https://lore.kernel.org/linux-fsdevel/20250309115207.908112-1-amir73il@gmail.com/

Amir Goldstein (6):
  fsnotify: add pre-content hooks on mmap()
  Revert "ext4: add pre-content fsnotify hook for DAX faults"
  Revert "xfs: add pre-content fsnotify hook for DAX faults"
  Revert "fsnotify: generate pre-content permission event on page fault"
  Revert "mm: don't allow huge faults for files with pre content
    watches"
  Revert "fanotify: disable readahead if we have pre-content watches"

 fs/ext4/file.c           |  3 --
 fs/xfs/xfs_file.c        | 13 ------
 include/linux/fsnotify.h | 21 ++++++++++
 include/linux/mm.h       |  1 -
 mm/filemap.c             | 86 ----------------------------------------
 mm/memory.c              | 19 ---------
 mm/nommu.c               |  7 ----
 mm/readahead.c           | 14 -------
 mm/util.c                |  3 ++
 9 files changed, 24 insertions(+), 143 deletions(-)

-- 
2.34.1