Commit 0014bd99 authored by Huang Ying's avatar Huang Ying Committed by Marcelo Tosatti

mm: export __get_user_pages

In most cases, get_user_pages and get_user_pages_fast should be used
to pin user pages in memory.  But sometimes, some special flags except
FOLL_GET, FOLL_WRITE and FOLL_FORCE are needed, for example in
following patch, KVM needs FOLL_HWPOISON.  To support these users,
__get_user_pages is exported directly.

There are some symbol name conflicts in infiniband driver, fixed them too.
Signed-off-by: default avatarHuang Ying <ying.huang@intel.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Michel Lespinasse <walken@google.com>
CC: Roland Dreier <roland@kernel.org>
CC: Ralph Campbell <infinipath@qlogic.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 91c9c3ed
......@@ -53,8 +53,8 @@ static void __ipath_release_user_pages(struct page **p, size_t num_pages,
}
/* call with current->mm->mmap_sem held */
static int __get_user_pages(unsigned long start_page, size_t num_pages,
struct page **p, struct vm_area_struct **vma)
static int __ipath_get_user_pages(unsigned long start_page, size_t num_pages,
struct page **p, struct vm_area_struct **vma)
{
unsigned long lock_limit;
size_t got;
......@@ -165,7 +165,7 @@ int ipath_get_user_pages(unsigned long start_page, size_t num_pages,
down_write(&current->mm->mmap_sem);
ret = __get_user_pages(start_page, num_pages, p, NULL);
ret = __ipath_get_user_pages(start_page, num_pages, p, NULL);
up_write(&current->mm->mmap_sem);
......
......@@ -51,8 +51,8 @@ static void __qib_release_user_pages(struct page **p, size_t num_pages,
/*
* Call with current->mm->mmap_sem held.
*/
static int __get_user_pages(unsigned long start_page, size_t num_pages,
struct page **p, struct vm_area_struct **vma)
static int __qib_get_user_pages(unsigned long start_page, size_t num_pages,
struct page **p, struct vm_area_struct **vma)
{
unsigned long lock_limit;
size_t got;
......@@ -136,7 +136,7 @@ int qib_get_user_pages(unsigned long start_page, size_t num_pages,
down_write(&current->mm->mmap_sem);
ret = __get_user_pages(start_page, num_pages, p, NULL);
ret = __qib_get_user_pages(start_page, num_pages, p, NULL);
up_write(&current->mm->mmap_sem);
......
......@@ -965,6 +965,10 @@ static inline int handle_mm_fault(struct mm_struct *mm,
extern int make_pages_present(unsigned long addr, unsigned long end);
extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int len, unsigned int foll_flags,
struct page **pages, struct vm_area_struct **vmas,
int *nonblocking);
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int nr_pages, int write, int force,
struct page **pages, struct vm_area_struct **vmas);
......
......@@ -245,11 +245,6 @@ static inline void mminit_validate_memmodel_limits(unsigned long *start_pfn,
}
#endif /* CONFIG_SPARSEMEM */
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int len, unsigned int foll_flags,
struct page **pages, struct vm_area_struct **vmas,
int *nonblocking);
#define ZONE_RECLAIM_NOSCAN -2
#define ZONE_RECLAIM_FULL -1
#define ZONE_RECLAIM_SOME 0
......
......@@ -1410,6 +1410,55 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
return page;
}
/**
* __get_user_pages() - pin user pages in memory
* @tsk: task_struct of target task
* @mm: mm_struct of target mm
* @start: starting user address
* @nr_pages: number of pages from start to pin
* @gup_flags: flags modifying pin behaviour
* @pages: array that receives pointers to the pages pinned.
* Should be at least nr_pages long. Or NULL, if caller
* only intends to ensure the pages are faulted in.
* @vmas: array of pointers to vmas corresponding to each page.
* Or NULL if the caller does not require them.
* @nonblocking: whether waiting for disk IO or mmap_sem contention
*
* Returns number of pages pinned. This may be fewer than the number
* requested. If nr_pages is 0 or negative, returns 0. If no pages
* were pinned, returns -errno. Each page returned must be released
* with a put_page() call when it is finished with. vmas will only
* remain valid while mmap_sem is held.
*
* Must be called with mmap_sem held for read or write.
*
* __get_user_pages walks a process's page tables and takes a reference to
* each struct page that each user address corresponds to at a given
* instant. That is, it takes the page that would be accessed if a user
* thread accesses the given user virtual address at that instant.
*
* This does not guarantee that the page exists in the user mappings when
* __get_user_pages returns, and there may even be a completely different
* page there in some cases (eg. if mmapped pagecache has been invalidated
* and subsequently re faulted). However it does guarantee that the page
* won't be freed completely. And mostly callers simply care that the page
* contains data that was valid *at some point in time*. Typically, an IO
* or similar operation cannot guarantee anything stronger anyway because
* locks can't be held over the syscall boundary.
*
* If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
* the page is written to, set_page_dirty (or set_page_dirty_lock, as
* appropriate) must be called after the page is finished with, and
* before put_page is called.
*
* If @nonblocking != NULL, __get_user_pages will not wait for disk IO
* or mmap_sem contention, and if waiting is needed to pin all pages,
* *@nonblocking will be set to 0.
*
* In most cases, get_user_pages or get_user_pages_fast should be used
* instead of __get_user_pages. __get_user_pages should be used only if
* you need some special @gup_flags.
*/
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int nr_pages, unsigned int gup_flags,
struct page **pages, struct vm_area_struct **vmas,
......@@ -1578,6 +1627,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
} while (nr_pages);
return i;
}
EXPORT_SYMBOL(__get_user_pages);
/**
* get_user_pages() - pin user pages in memory
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment