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

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

drivers/infiniband/hw/ipath/ipath_user_pages.c

+3 −3
Original line number Diff line number Diff line
@@ -53,7 +53,7 @@ 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,

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;
@@ -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);

drivers/infiniband/hw/qib/qib_user_pages.c

+3 −3
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ 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,

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;
@@ -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);

include/linux/mm.h

+4 −0
Original line number Diff line number Diff line
@@ -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);

mm/internal.h

+0 −5
Original line number Diff line number Diff line
@@ -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

mm/memory.c

+50 −0
Original line number Diff line number Diff line
@@ -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