dax/fsdev: clear pgmap ops and owner on unbind

Browse source

fsdev_dax_probe() sets pgmap->ops = &fsdev_pagemap_ops and
pgmap->owner = dev_dax, but nothing ever clears them. For a dynamic
device the pgmap is devm-allocated and freed on unbind, so this is
harmless. For a static device the pgmap is the shared, long-lived one
owned by the dax bus (kill_dev_dax() only NULLs dev_dax->pgmap for the
non-static case), and device.c's probe sets only pgmap->type, never
clearing ops/owner.

So after fsdev unbinds a static device the stale fsdev_pagemap_ops
survives on the shared pgmap. If the device is then rebound to
device_dax (MEMORY_DEVICE_GENERIC, which installs no ->memory_failure),
or the fsdev_dax module is unloaded, a subsequent memory_failure on that
pgmap dispatches through the stale -- and possibly freed -- handler.

Register a devm action that clears pgmap->ops and pgmap->owner on unbind,
symmetric with setting them at probe, so the pgmap carries no fsdev state
once fsdev is detached.

Suggested-by: Richard Cheng <icheng@nvidia.com>
Fixes: d5406bd458 ("dax: add fsdev.c driver for fs-dax on character dax")
Signed-off-by: John Groves <john@groves.net>
Reviewed-by: Richard Cheng <icheng@nvidia.com>
Link: https://patch.msgid.link/0100019ecc094b6e-fc163bde-0396-4a33-909f-fb88e740be27-000000@email.amazonses.com
Signed-off-by: Alison Schofield <alison.schofield@intel.com>

...

This commit is contained in:

John Groves 2026-06-15 16:07:01 +00:00 • committed by Alison Schofield

parent caf906009d

commit f48884ac31

1 changed files with 22 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

22

drivers/dax/fsdev.c

View file