linux-toradex.git/kernel/memremap.c, branch v4.18-rc4

mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPS

2018-05-22T13:59:39+00:00

In preparation for fixing dax-dma-vs-unmap issues, filesystems need to
be able to rely on the fact that they will get wakeups on dev_pagemap
page-idle events. Introduce MEMORY_DEVICE_FS_DAX and
generic_dax_page_free() as common indicator / infrastructure for dax
filesytems to require. With this change there are no users of the
MEMORY_DEVICE_HOST designation, so remove it.

The HMM sub-system extended dev_pagemap to arrange a callback when a
dev_pagemap managed page is freed. Since a dev_pagemap page is free /
idle when its reference count is 1 it requires an additional branch to
check the page-type at put_page() time. Given put_page() is a hot-path
we do not want to incur that check if HMM is not in use, so a static
branch is used to avoid that overhead when not necessary.

Now, the FS_DAX implementation wants to reuse this mechanism for
receiving dev_pagemap ->page_free() callbacks. Rework the HMM-specific
static-key into a generic mechanism that either HMM or FS_DAX code paths
can enable.

For ARCH=um builds, and any other arch that lacks ZONE_DEVICE support,
care must be taken to compile out the DEV_PAGEMAP_OPS infrastructure.
However, we still need to support FS_DAX in the FS_DAX_LIMITED case
implemented by the s390/dcssblk driver.

Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Michal Hocko 
Reported-by: kbuild test robot 
Reported-by: Thomas Meyer 
Reported-by: Dave Jiang 
Cc: "Jérôme Glisse" 
Reviewed-by: Jan Kara 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Dan Williams

memremap: split devm_memremap_pages() and memremap() infrastructure

2018-05-16T06:08:33+00:00

Currently, kernel/memremap.c contains generic code for supporting
memremap() (CONFIG_HAS_IOMEM) and devm_memremap_pages()
(CONFIG_ZONE_DEVICE). This causes ongoing build maintenance problems as
additions to memremap.c, especially for the ZONE_DEVICE case, need to be
careful about being placed in ifdef guards. Remove the need for these
ifdef guards by moving the ZONE_DEVICE support functions to their own
compilation unit.

Cc: "Jérôme Glisse" 
Cc: Ross Zwisler 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Signed-off-by: Dan Williams

kernel/memremap: Remove stale devres_free() call

2018-03-06T18:58:54+00:00

devm_memremap_pages() was re-worked in e8d513483300 "memremap: change
devm_memremap_pages interface to use struct dev_pagemap" to take a
caller allocated struct dev_pagemap as a function parameter. A call to
devres_free() was left in the error cleanup path which results in a
kernel panic if the remap fails for some reason. Remove it to fix the
panic and let devm_memremap_pages() fail gracefully.

Fixes: e8d513483300 ("memremap: change devm_memremap_pages interface...")
Signed-off-by: Oliver O'Halloran 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Logan Gunthorpe 
Signed-off-by: Dan Williams

memremap: fix softlockup reports at teardown

2018-03-03T03:34:50+00:00

The cond_resched() currently in the setup path needs to be duplicated in
the teardown path. Rather than require each instance of
for_each_device_pfn() to open code the same sequence, embed it in the
helper.

Link: https://github.com/intel/ixpdimm_sw/issues/11
Cc: "Jérôme Glisse" 
Cc: Michal Hocko 
Cc: Christoph Hellwig 
Cc: 
Fixes: 71389703839e ("mm, zone_device: Replace {get, put}_zone_device_page()...")
Signed-off-by: Dan Williams

mm: Fix devm_memremap_pages() collision handling

2018-01-20T00:29:56+00:00

If devm_memremap_pages() detects a collision while adding entries
to the radix-tree, we call pgmap_radix_release(). Unfortunately,
the function removes *all* entries for the range -- including the
entries that caused the collision in the first place.

Modify pgmap_radix_release() to take an additional argument to
indicate where to stop, so that only newly added entries are removed
from the tree.

Cc: 
Fixes: 9476df7d80df ("mm: introduce find_dev_pagemap()")
Signed-off-by: Jan H. Schönherr 
Signed-off-by: Dan Williams

mm: Fix memory size alignment in devm_memremap_pages_release()

2018-01-20T00:29:48+00:00

The functions devm_memremap_pages() and devm_memremap_pages_release() use
different ways to calculate the section-aligned amount of memory. The
latter function may use an incorrect size if the memory region is small
but straddles a section border.

Use the same code for both.

Cc: 
Fixes: 5f29a77cd957 ("mm: fix mixed zone detection in devm_memremap_pages")
Signed-off-by: Jan H. Schönherr 
Signed-off-by: Dan Williams

memremap: merge find_dev_pagemap into get_dev_pagemap

2018-01-08T19:46:23+00:00

There is only one caller of the trivial function find_dev_pagemap left,
so just merge it into the caller.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Dan Williams

memremap: change devm_memremap_pages interface to use struct dev_pagemap

2018-01-08T19:46:23+00:00

This new interface is similar to how struct device (and many others)
work. The caller initializes a 'struct dev_pagemap' as required
and calls 'devm_memremap_pages'. This allows the pagemap structure to
be embedded in another structure and thus container_of can be used. In
this way application specific members can be stored in a containing
struct.

This will be used by the P2P infrastructure and HMM could probably
be cleaned up to use it as well (instead of having it's own, similar
'hmm_devmem_pages_create' function).

Signed-off-by: Logan Gunthorpe 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Dan Williams

memremap: drop private struct page_map

2018-01-08T19:46:23+00:00

'struct page_map' is a private structure of 'struct dev_pagemap' but the
latter replicates all the same fields as the former so there isn't much
value in it. Thus drop it in favour of a completely public struct.

This is a clean up in preperation for a more generally useful
'devm_memeremap_pages' interface.

Signed-off-by: Logan Gunthorpe 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Dan Williams

memremap: simplify duplicate region handling in devm_memremap_pages

2018-01-08T19:46:23+00:00

__radix_tree_insert already checks for duplicates and returns -EEXIST in
that case, so remove the duplicate (and racy) duplicates check.

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