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mm: gup: add __get_user_pages_unlocked to customize gup_flags

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Some callers (like KVM) may want to set the gup_flags like FOLL_HWPOSION
to get a proper -EHWPOSION retval instead of -EFAULT to take a more
appropriate action if get_user_pages runs into a memory failure.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Arcangeli 2015-02-11 15:27:20 -08:00 committed by Linus Torvalds
parent f0818f472d
commit 0fd71a56f4
3 changed files with 49 additions and 15 deletions
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4
include/linux/mm.h
View File

@ -1265,6 +1265,10 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
int *locked);
long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags);
long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages);

44
mm/gup.c
View File

@ -582,9 +582,9 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
int write, int force,
struct page **pages,
struct vm_area_struct **vmas,
int *locked, bool notify_drop)
int *locked, bool notify_drop,
unsigned int flags)
{
int flags = FOLL_TOUCH;
long ret, pages_done;
bool lock_dropped;
@ -698,10 +698,36 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
int *locked)
{
return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
pages, NULL, locked, true);
pages, NULL, locked, true, FOLL_TOUCH);
}
EXPORT_SYMBOL(get_user_pages_locked);
/*
* Same as get_user_pages_unlocked(...., FOLL_TOUCH) but it allows to
* pass additional gup_flags as last parameter (like FOLL_HWPOISON).
*
* NOTE: here FOLL_TOUCH is not set implicitly and must be set by the
* caller if required (just like with __get_user_pages). "FOLL_GET",
* "FOLL_WRITE" and "FOLL_FORCE" are set implicitly as needed
* according to the parameters "pages", "write", "force"
* respectively.
*/
__always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags)
{
long ret;
int locked = 1;
down_read(&mm->mmap_sem);
ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
pages, NULL, &locked, false, gup_flags);
if (locked)
up_read(&mm->mmap_sem);
return ret;
}
EXPORT_SYMBOL(__get_user_pages_unlocked);
/*
* get_user_pages_unlocked() is suitable to replace the form:
*
@ -723,14 +749,8 @@ long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages)
{
long ret;
int locked = 1;
down_read(&mm->mmap_sem);
ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
pages, NULL, &locked, false);
if (locked)
up_read(&mm->mmap_sem);
return ret;
return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write,
force, pages, FOLL_TOUCH);
}
EXPORT_SYMBOL(get_user_pages_unlocked);
@ -794,7 +814,7 @@ long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
int force, struct page **pages, struct vm_area_struct **vmas)
{
return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
pages, vmas, NULL, false);
pages, vmas, NULL, false, FOLL_TOUCH);
}
EXPORT_SYMBOL(get_user_pages);

14
mm/nommu.c
View File

@ -224,9 +224,10 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
}
EXPORT_SYMBOL(get_user_pages_locked);
long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages)
int write, int force, struct page **pages,
unsigned int gup_flags)
{
long ret;
down_read(&mm->mmap_sem);
@ -235,6 +236,15 @@ long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
up_read(&mm->mmap_sem);
return ret;
}
EXPORT_SYMBOL(__get_user_pages_unlocked);
long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages)
{
return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write,
force, pages, 0);
}
EXPORT_SYMBOL(get_user_pages_unlocked);
/**