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mm: unexport __get_user_pages_unlocked()

Unexport the low-level __get_user_pages_unlocked() function and replaces
invocations with calls to more appropriate higher-level functions.

In hva_to_pfn_slow() we are able to replace __get_user_pages_unlocked()
with get_user_pages_unlocked() since we can now pass gup_flags.

In async_pf_execute() and process_vm_rw_single_vec() we need to pass
different tsk, mm arguments so get_user_pages_remote() is the sane
replacement in these cases (having added manual acquisition and release
of mmap_sem.)

Additionally get_user_pages_remote() reintroduces use of the FOLL_TOUCH
flag.  However, this flag was originally silently dropped by commit
1e98779 ("mm/gup: Introduce get_user_pages_remote()"), so this
appears to have been unintentional and reintroducing it is therefore not
an issue.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20161027095141.2569-3-lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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lorenzo-stoakes authored and torvalds committed Dec 14, 2016
1 parent 5b56d49 commit 8b7457ef9a9eb46cd1675d40d8e1fd3c47a38395
Showing with 25 additions and 21 deletions.
  1. +0 −3 include/linux/mm.h
  2. +4 −4 mm/gup.c
  3. +4 −4 mm/nommu.c
  4. +8 −4 mm/process_vm_access.c
  5. +7 −3 virt/kvm/async_pf.c
  6. +2 −3 virt/kvm/kvm_main.c
@@ -1280,9 +1280,6 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
struct vm_area_struct **vmas);
long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, 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,
struct page **pages, unsigned int gup_flags);
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags);
int get_user_pages_fast(unsigned long start, int nr_pages, int write,
@@ -865,9 +865,10 @@ EXPORT_SYMBOL(get_user_pages_locked);
* caller if required (just like with __get_user_pages). "FOLL_GET"
* is set implicitly if "pages" is non-NULL.
*/
__always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags)
static __always_inline long __get_user_pages_unlocked(struct task_struct *tsk,
struct mm_struct *mm, unsigned long start,
unsigned long nr_pages, struct page **pages,
unsigned int gup_flags)
{
long ret;
int locked = 1;
@@ -879,7 +880,6 @@ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct m
up_read(&mm->mmap_sem);
return ret;
}
EXPORT_SYMBOL(__get_user_pages_unlocked);

/*
* get_user_pages_unlocked() is suitable to replace the form:
@@ -176,9 +176,10 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
}
EXPORT_SYMBOL(get_user_pages_locked);

long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags)
static long __get_user_pages_unlocked(struct task_struct *tsk,
struct mm_struct *mm, unsigned long start,
unsigned long nr_pages, struct page **pages,
unsigned int gup_flags)
{
long ret;
down_read(&mm->mmap_sem);
@@ -187,7 +188,6 @@ 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(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags)
@@ -88,7 +88,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
ssize_t rc = 0;
unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
/ sizeof(struct pages *);
unsigned int flags = FOLL_REMOTE;
unsigned int flags = 0;

/* Work out address and page range required */
if (len == 0)
@@ -100,15 +100,19 @@ static int process_vm_rw_single_vec(unsigned long addr,

while (!rc && nr_pages && iov_iter_count(iter)) {
int pages = min(nr_pages, max_pages_per_loop);
int locked = 1;
size_t bytes;

/*
* Get the pages we're interested in. We must
* add FOLL_REMOTE because task/mm might not
* access remotely because task/mm might not
* current/current->mm
*/
pages = __get_user_pages_unlocked(task, mm, pa, pages,
process_pages, flags);
down_read(&mm->mmap_sem);
pages = get_user_pages_remote(task, mm, pa, pages, flags,
process_pages, NULL, &locked);
if (locked)
up_read(&mm->mmap_sem);
if (pages <= 0)
return -EFAULT;

@@ -76,16 +76,20 @@ static void async_pf_execute(struct work_struct *work)
struct kvm_vcpu *vcpu = apf->vcpu;
unsigned long addr = apf->addr;
gva_t gva = apf->gva;
int locked = 1;

might_sleep();

/*
* This work is run asynchromously to the task which owns
* mm and might be done in another context, so we must
* use FOLL_REMOTE.
* access remotely.
*/
__get_user_pages_unlocked(NULL, mm, addr, 1, NULL,
FOLL_WRITE | FOLL_REMOTE);
down_read(&mm->mmap_sem);
get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
&locked);
if (locked)
up_read(&mm->mmap_sem);

kvm_async_page_present_sync(vcpu, apf);

@@ -1418,13 +1418,12 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
npages = get_user_page_nowait(addr, write_fault, page);
up_read(&current->mm->mmap_sem);
} else {
unsigned int flags = FOLL_TOUCH | FOLL_HWPOISON;
unsigned int flags = FOLL_HWPOISON;

if (write_fault)
flags |= FOLL_WRITE;

npages = __get_user_pages_unlocked(current, current->mm, addr, 1,
page, flags);
npages = get_user_pages_unlocked(addr, 1, page, flags);
}
if (npages != 1)
return npages;

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