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mm/hmm: fix memremap.h, move dev_page_fault_t callback to hmm

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The kbuild robot reported the following on a development branch that used
memremap.h in a new path:

   In file included from arch/m68k/include/asm/pgtable_mm.h:148:0,
                     from arch/m68k/include/asm/pgtable.h:5,
                     from include/linux/memremap.h:7,
                     from drivers//dax/bus.c:3:
    arch/m68k/include/asm/motorola_pgtable.h: In function 'pgd_offset':
 >> arch/m68k/include/asm/motorola_pgtable.h:199:11: error: dereferencing pointer to incomplete type 'const struct mm_struct'
      return mm->pgd + pgd_index(address);
               ^~

The ->page_fault() callback is specific to HMM.  Move it to 'struct
hmm_devmem' where the unusual asm/pgtable.h dependency can be contained in
include/linux/hmm.h.  Longer term refactoring this dependency out of HMM
is recommended, but in the meantime memremap.h remains generic.

Link: http://lkml.kernel.org/r/154534090899.3120190.6652620807617715272.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 5042db43cc ("mm/ZONE_DEVICE: new type of ZONE_DEVICE memory...")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams 2018-12-28 00:39:46 -08:00 • committed by Linus Torvalds
parent c86aa7bbfd
commit 063a7d1d36
4 changed files with 31 additions and 35 deletions
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32
include/linux/memremap.h
View file

@ -4,8 +4,6 @@
#include <linux/ioport.h>
#include <linux/percpu-refcount.h>
#include <asm/pgtable.h>
struct resource;
struct device;
@ -66,47 +64,18 @@ enum memory_type {
};
/*
* For MEMORY_DEVICE_PRIVATE we use ZONE_DEVICE and extend it with two
* callbacks:
* page_fault()
* page_free()
*
* Additional notes about MEMORY_DEVICE_PRIVATE may be found in
* include/linux/hmm.h and Documentation/vm/hmm.rst. There is also a brief
* explanation in include/linux/memory_hotplug.h.
*
* The page_fault() callback must migrate page back, from device memory to
* system memory, so that the CPU can access it. This might fail for various
* reasons (device issues, device have been unplugged, ...). When such error
* conditions happen, the page_fault() callback must return VM_FAULT_SIGBUS and
* set the CPU page table entry to "poisoned".
*
* Note that because memory cgroup charges are transferred to the device memory,
* this should never fail due to memory restrictions. However, allocation
* of a regular system page might still fail because we are out of memory. If
* that happens, the page_fault() callback must return VM_FAULT_OOM.
*
* The page_fault() callback can also try to migrate back multiple pages in one
* chunk, as an optimization. It must, however, prioritize the faulting address
* over all the others.
*
*
* The page_free() callback is called once the page refcount reaches 1
* (ZONE_DEVICE pages never reach 0 refcount unless there is a refcount bug.
* This allows the device driver to implement its own memory management.)
*
* For MEMORY_DEVICE_PUBLIC only the page_free() callback matter.
*/
typedef int (*dev_page_fault_t)(struct vm_area_struct *vma,
unsigned long addr,
const struct page *page,
unsigned int flags,
pmd_t *pmdp);
typedef void (*dev_page_free_t)(struct page *page, void *data);
/**
* struct dev_pagemap - metadata for ZONE_DEVICE mappings
* @page_fault: callback when CPU fault on an unaddressable device page
* @page_free: free page callback when page refcount reaches 1
* @altmap: pre-allocated/reserved memory for vmemmap allocations
* @res: physical address range covered by @ref
@ -117,7 +86,6 @@ typedef void (*dev_page_free_t)(struct page *page, void *data);
* @type: memory type: see MEMORY_* in memory_hotplug.h
*/
struct dev_pagemap {
dev_page_fault_t page_fault;
dev_page_free_t page_free;
struct vmem_altmap altmap;
bool altmap_valid;