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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
include/linux/hmm.h
View File

@ -69,6 +69,7 @@
#define LINUX_HMM_H
#include <linux/kconfig.h>
#include <asm/pgtable.h>
#if IS_ENABLED(CONFIG_HMM)
@ -486,6 +487,7 @@ struct hmm_devmem_ops {
* @device: device to bind resource to
* @ops: memory operations callback
* @ref: per CPU refcount
* @page_fault: callback when CPU fault on an unaddressable device page
*
* This an helper structure for device drivers that do not wish to implement
* the gory details related to hotplugging new memoy and allocating struct
@ -493,7 +495,28 @@ struct hmm_devmem_ops {
*
* Device drivers can directly use ZONE_DEVICE memory on their own if they
* wish to do so.
*
* 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.
*/
typedef int (*dev_page_fault_t)(struct vm_area_struct *vma,
unsigned long addr,
const struct page *page,
unsigned int flags,
pmd_t *pmdp);
struct hmm_devmem {
struct completion completion;
unsigned long pfn_first;
@ -503,6 +526,7 @@ struct hmm_devmem {
struct dev_pagemap pagemap;
const struct hmm_devmem_ops *ops;
struct percpu_ref ref;
dev_page_fault_t page_fault;
};
/*

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;

6
kernel/memremap.c
View File

@ -11,6 +11,7 @@
#include <linux/types.h>
#include <linux/wait_bit.h>
#include <linux/xarray.h>
#include <linux/hmm.h>
static DEFINE_XARRAY(pgmap_array);
#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
@ -24,6 +25,9 @@ vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
pmd_t *pmdp)
{
struct page *page = device_private_entry_to_page(entry);
struct hmm_devmem *devmem;
devmem = container_of(page->pgmap, typeof(*devmem), pagemap);
/*
* The page_fault() callback must migrate page back to system memory
@ -39,7 +43,7 @@ vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
* There is a more in-depth description of what that callback can and
* cannot do, in include/linux/memremap.h
*/
return page->pgmap->page_fault(vma, addr, page, flags, pmdp);
return devmem->page_fault(vma, addr, page, flags, pmdp);
}
EXPORT_SYMBOL(device_private_entry_fault);
#endif /* CONFIG_DEVICE_PRIVATE */

4
mm/hmm.c
View File

@ -1087,10 +1087,10 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
devmem->pfn_last = devmem->pfn_first +
(resource_size(devmem->resource) >> PAGE_SHIFT);
devmem->page_fault = hmm_devmem_fault;
devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
devmem->pagemap.res = *devmem->resource;
devmem->pagemap.page_fault = hmm_devmem_fault;
devmem->pagemap.page_free = hmm_devmem_free;
devmem->pagemap.altmap_valid = false;
devmem->pagemap.ref = &devmem->ref;
@ -1141,10 +1141,10 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
devmem->pfn_last = devmem->pfn_first +
(resource_size(devmem->resource) >> PAGE_SHIFT);
devmem->page_fault = hmm_devmem_fault;
devmem->pagemap.type = MEMORY_DEVICE_PUBLIC;
devmem->pagemap.res = *devmem->resource;
devmem->pagemap.page_fault = hmm_devmem_fault;
devmem->pagemap.page_free = hmm_devmem_free;
devmem->pagemap.altmap_valid = false;
devmem->pagemap.ref = &devmem->ref;