linux.git/include/linux/hmm.h, branch v5.7-rc2

mm/hmm: remove HMM_FAULT_SNAPSHOT

2020-03-27T23:19:24+00:00

Now that flags are handled on a fine-grained per-page basis this global
flag is redundant and has a confusing overlap with the pfn_flags_mask and
default_flags.

Normalize the HMM_FAULT_SNAPSHOT behavior into one place. Callers needing
the SNAPSHOT behavior should set a pfn_flags_mask and default_flags that
always results in a cleared HMM_PFN_VALID. Then no pages will be faulted,
and HMM_FAULT_SNAPSHOT is not a special flow that overrides the masking
mechanism.

As this is the last flag, also remove the flags argument. If future flags
are needed they can be part of the struct hmm_range function arguments.

Link: https://lore.kernel.org/r/20200327200021.29372-5-jgg@ziepe.ca
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jason Gunthorpe

mm/hmm: remove unused code and tidy comments

2020-03-27T23:19:24+00:00

Delete several functions that are never called, fix some desync between
comments and structure content, toss the now out of date top of file
header, and move one function only used by hmm.c into hmm.c

Link: https://lore.kernel.org/r/20200327200021.29372-4-jgg@ziepe.ca
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jason Gunthorpe

mm/hmm: check the device private page owner in hmm_range_fault()

2020-03-26T17:33:38+00:00

hmm_range_fault() will succeed for any kind of device private memory, even
if it doesn't belong to the calling entity.  While nouveau has some crude
checks for that, they are broken because they assume nouveau is the only
user of device private memory.  Fix this by passing in an expected pgmap
owner in the hmm_range_fault structure.

If a device_private page is found and doesn't match the owner then it is
treated as an non-present and non-faultable page.

This prevents a bug in amdgpu, where it doesn't know how to handle
device_private pages, but hmm_range_fault would return them anyhow.

Fixes: 4ef589dc9b10 ("mm/hmm/devmem: device memory hotplug using ZONE_DEVICE")
Link: https://lore.kernel.org/r/20200316193216.920734-5-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Ralph Campbell 
Signed-off-by: Jason Gunthorpe

mm: simplify device private page handling in hmm_range_fault

2020-03-26T17:33:38+00:00

Remove the HMM_PFN_DEVICE_PRIVATE flag, no driver has ever set this flag
on input, and the only place that uses it on output can be trivially
changed to use is_device_private_page().

This removes the ability to request that device_private pages are faulted
back into system memory.

Link: https://lore.kernel.org/r/20200316193216.920734-4-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Signed-off-by: Jason Gunthorpe

mm/hmm: remove the unused HMM_FAULT_ALLOW_RETRY flag

2020-03-26T17:33:37+00:00

The HMM_FAULT_ALLOW_RETRY isn't used anywhere in the tree.  Remove it and
the weird -EAGAIN handling where handle_mm_fault() drops the mmap_sem.

Link: https://lore.kernel.org/r/20200316135310.899364-3-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Signed-off-by: Jason Gunthorpe

mm/hmm: don't provide a stub for hmm_range_fault()

2020-03-26T17:33:37+00:00

All callers of hmm_range_fault depend on CONFIG_HMM_MIRROR, so don't
bother with a stub.

Link: https://lore.kernel.org/r/20200316135310.899364-2-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: Zi Yan 
Reviewed-by: Jason Gunthorpe 
Signed-off-by: Jason Gunthorpe

mm/hmm: remove hmm_range_dma_map and hmm_range_dma_unmap

2019-11-23T23:56:45+00:00

These two functions have never been used since they were added.

Link: https://lore.kernel.org/r/20191113134528.21187-1-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: John Hubbard 
Reviewed-by: Jason Gunthorpe 
Signed-off-by: Jason Gunthorpe

mm/hmm: remove hmm_mirror and related

2019-11-23T23:56:45+00:00

The only two users of this are now converted to use mmu_interval_notifier,
delete all the code and update hmm.rst.

Link: https://lore.kernel.org/r/20191112202231.3856-14-jgg@ziepe.ca
Reviewed-by: Jérôme Glisse 
Tested-by: Ralph Campbell 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jason Gunthorpe

mm/hmm: define the pre-processor related parts of hmm.h even if disabled

2019-11-23T23:56:44+00:00

Only the function calls are stubbed out with static inlines that always
fail. This is the standard way to write a header for an optional component
and makes it easier for drivers that only optionally need HMM_MIRROR.

Link: https://lore.kernel.org/r/20191112202231.3856-5-jgg@ziepe.ca
Reviewed-by: Jérôme Glisse 
Tested-by: Ralph Campbell 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jason Gunthorpe

mm/hmm: allow hmm_range to be used with a mmu_interval_notifier or hmm_mirror

2019-11-23T23:56:44+00:00

hmm_mirror's handling of ranges does not use a sequence count which
results in this bug:

         CPU0                                   CPU1
                                     hmm_range_wait_until_valid(range)
                                         valid == true
                                     hmm_range_fault(range)
hmm_invalidate_range_start()
   range->valid = false
hmm_invalidate_range_end()
   range->valid = true
                                     hmm_range_valid(range)
                                          valid == true

Where the hmm_range_valid() should not have succeeded.

Adding the required sequence count would make it nearly identical to the
new mmu_interval_notifier. Instead replace the hmm_mirror stuff with
mmu_interval_notifier.

Co-existence of the two APIs is the first step.

Link: https://lore.kernel.org/r/20191112202231.3856-4-jgg@ziepe.ca
Reviewed-by: Jérôme Glisse 
Tested-by: Philip Yang 
Tested-by: Ralph Campbell 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jason Gunthorpe