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Commit 0d731759 authored by Lorenzo Stoakes's avatar Lorenzo Stoakes Committed by Linus Torvalds
Browse files

mm: unexport __get_user_pages() 



This patch unexports the low-level __get_user_pages() function.

Recent refactoring of the get_user_pages* functions allow flags to be
passed through get_user_pages() which eliminates the need for access to
this function from its one user, kvm.

We can see that the two calls to get_user_pages() which replace
__get_user_pages() in kvm_main.c are equivalent by examining their call
stacks:

  get_user_page_nowait():
    get_user_pages(start, 1, flags, page, NULL)
    __get_user_pages_locked(current, current->mm, start, 1, page, NULL, NULL,
			    false, flags | FOLL_TOUCH)
    __get_user_pages(current, current->mm, start, 1,
		     flags | FOLL_TOUCH | FOLL_GET, page, NULL, NULL)

  check_user_page_hwpoison():
    get_user_pages(addr, 1, flags, NULL, NULL)
    __get_user_pages_locked(current, current->mm, addr, 1, NULL, NULL, NULL,
			    false, flags | FOLL_TOUCH)
    __get_user_pages(current, current->mm, addr, 1, flags | FOLL_TOUCH, NULL,
		     NULL, NULL)

Signed-off-by: default avatarLorenzo Stoakes <lstoakes@gmail.com>
Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 272ddc8b

include/linux/mm.h

+0 −4
Original line number Diff line number Diff line
@@ -1271,10 +1271,6 @@ extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void * 
extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,

		void *buf, int len, unsigned int gup_flags);



long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,

		      unsigned long start, unsigned long nr_pages,

		      unsigned int foll_flags, struct page **pages,

		      struct vm_area_struct **vmas, int *nonblocking);

long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,

			    unsigned long start, unsigned long nr_pages,

			    unsigned int gup_flags, struct page **pages,

mm/gup.c

+1 −2
Original line number Diff line number Diff line
@@ -526,7 +526,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) 
 * instead of __get_user_pages. __get_user_pages should be used only if

 * you need some special @gup_flags.

 */

long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,

static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,

		unsigned long start, unsigned long nr_pages,

		unsigned int gup_flags, struct page **pages,

		struct vm_area_struct **vmas, int *nonblocking)
@@ -631,7 +631,6 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 
	} while (nr_pages);

	return i;

}

EXPORT_SYMBOL(__get_user_pages);



bool vma_permits_fault(struct vm_area_struct *vma, unsigned int fault_flags)

{

mm/nommu.c

+1 −1
Original line number Diff line number Diff line
@@ -109,7 +109,7 @@ unsigned int kobjsize(const void *objp) 
	return PAGE_SIZE << compound_order(page);

}



long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,

static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,

		      unsigned long start, unsigned long nr_pages,

		      unsigned int foll_flags, struct page **pages,

		      struct vm_area_struct **vmas, int *nonblocking)

virt/kvm/kvm_main.c

+4 −6
Original line number Diff line number Diff line
@@ -1346,21 +1346,19 @@ unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *w 
static int get_user_page_nowait(unsigned long start, int write,

		struct page **page)

{

	int flags = FOLL_TOUCH | FOLL_NOWAIT | FOLL_HWPOISON | FOLL_GET;

	int flags = FOLL_NOWAIT | FOLL_HWPOISON;



	if (write)

		flags |= FOLL_WRITE;



	return __get_user_pages(current, current->mm, start, 1, flags, page,

			NULL, NULL);

	return get_user_pages(start, 1, flags, page, NULL);

}



static inline int check_user_page_hwpoison(unsigned long addr)

{

	int rc, flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_WRITE;

	int rc, flags = FOLL_HWPOISON | FOLL_WRITE;



	rc = __get_user_pages(current, current->mm, addr, 1,

			      flags, NULL, NULL, NULL);

	rc = get_user_pages(addr, 1, flags, NULL, NULL);

	return rc == -EHWPOISON;

}