linux-stable.git/include/linux/memremap.h, branch v5.3.3

memremap: provide an optional internal refcount in struct dev_pagemap

2019-07-02T17:32:44+00:00

Provide an internal refcounting logic if no ->ref field is provided
in the pagemap passed into devm_memremap_pages so that callers don't
have to reinvent it poorly.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ira Weiny 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

memremap: replace the altmap_valid field with a PGMAP_ALTMAP_VALID flag

2019-07-02T17:32:44+00:00

Add a flags field to struct dev_pagemap to replace the altmap_valid
boolean to be a little more extensible.  Also add a pgmap_altmap() helper
to find the optional altmap and clean up the code using the altmap using
it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ira Weiny 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

memremap: remove the data field in struct dev_pagemap

2019-07-02T17:32:44+00:00

struct dev_pagemap is always embedded into a containing structure, so
there is no need to an additional private data field.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

memremap: add a migrate_to_ram method to struct dev_pagemap_ops

2019-07-02T17:32:44+00:00

This replaces the hacky ->fault callback, which is currently directly
called from common code through a hmm specific data structure as an
exercise in layering violations.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ralph Campbell 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

memremap: pass a struct dev_pagemap to ->kill and ->cleanup

2019-07-02T17:32:44+00:00

Passing the actual typed structure leads to more understandable code
vs just passing the ref member.

Reported-by: Logan Gunthorpe 
Signed-off-by: Christoph Hellwig 
Reviewed-by: Logan Gunthorpe 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

memremap: move dev_pagemap callbacks into a separate structure

2019-07-02T17:32:44+00:00

The dev_pagemap is a growing too many callbacks.  Move them into a
separate ops structure so that they are not duplicated for multiple
instances, and an attacker can't easily overwrite them.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Logan Gunthorpe 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

memremap: validate the pagemap type passed to devm_memremap_pages

2019-07-02T17:32:44+00:00

Most pgmap types are only supported when certain config options are
enabled.  Check for a type that is valid for the current configuration
before setting up the pagemap.  For this the usage of the 0 type for
device dax gets replaced with an explicit MEMORY_DEVICE_DEVDAX type.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ira Weiny 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

mm: remove MEMORY_DEVICE_PUBLIC support

2019-07-02T17:32:43+00:00

The code hasn't been used since it was added to the tree, and doesn't
appear to actually be usable.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Acked-by: Michal Hocko 
Reviewed-by: Dan Williams 
Tested-by: Dan Williams 
Signed-off-by: Jason Gunthorpe

mm/devm_memremap_pages: fix final page put race

2019-06-14T03:34:56+00:00

Logan noticed that devm_memremap_pages_release() kills the percpu_ref
drops all the page references that were acquired at init and then
immediately proceeds to unplug, arch_remove_memory(), the backing pages
for the pagemap.  If for some reason device shutdown actually collides
with a busy / elevated-ref-count page then arch_remove_memory() should
be deferred until after that reference is dropped.

As it stands the "wait for last page ref drop" happens *after*
devm_memremap_pages_release() returns, which is obviously too late and
can lead to crashes.

Fix this situation by assigning the responsibility to wait for the
percpu_ref to go idle to devm_memremap_pages() with a new ->cleanup()
callback.  Implement the new cleanup callback for all
devm_memremap_pages() users: pmem, devdax, hmm, and p2pdma.

Link: http://lkml.kernel.org/r/155727339156.292046.5432007428235387859.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 41e94a851304 ("add devm_memremap_pages")
Signed-off-by: Dan Williams 
Reported-by: Logan Gunthorpe 
Reviewed-by: Ira Weiny 
Reviewed-by: Logan Gunthorpe 
Cc: Bjorn Helgaas 
Cc: "Jérôme Glisse" 
Cc: Christoph Hellwig 
Cc: Greg Kroah-Hartman 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/devm_memremap_pages: introduce devm_memunmap_pages

2019-06-14T03:34:56+00:00

Use the new devm_release_action() facility to allow
devm_memremap_pages_release() to be manually triggered.

Link: http://lkml.kernel.org/r/155727337088.292046.5774214552136776763.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams 
Reviewed-by: Ira Weiny 
Reviewed-by: Logan Gunthorpe 
Cc: Bjorn Helgaas 
Cc: Christoph Hellwig 
Cc: Greg Kroah-Hartman 
Cc: "Jérôme Glisse" 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds