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f48884ac31
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>
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