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Date: Wed, 29 Oct 2014 17:35:17 +0100
From: Andrea Arcangeli <aarcange@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc: "Kirill A. Shutemov" <kirill@...temov.name>,
Michel Lespinasse <walken@...gle.com>,
Andrew Jones <drjones@...hat.com>,
Hugh Dickins <hughd@...gle.com>, Mel Gorman <mgorman@...e.de>,
Andres Lagar-Cavilla <andreslc@...gle.com>,
Minchan Kim <minchan@...nel.org>,
KOSAKI Motohiro <kosaki.motohiro@...il.com>,
"\\\"Dr. David Alan Gilbert\\\"" <dgilbert@...hat.com>,
Peter Feiner <pfeiner@...gle.com>,
Peter Zijlstra <peterz@...radead.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
James Bottomley <James.Bottomley@...senPartnership.com>,
David Miller <davem@...emloft.net>,
Steve Capper <steve.capper@...aro.org>,
Johannes Weiner <jweiner@...hat.com>
Subject: [PATCH 2/5] mm: gup: add __get_user_pages_unlocked to customize gup_flags
Some caller (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@...hat.com>
---
include/linux/mm.h | 4 ++++
mm/gup.c | 44 ++++++++++++++++++++++++++++++++------------
mm/nommu.c | 16 +++++++++++++---
3 files changed, 49 insertions(+), 15 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 99831d9..9a5ada3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1222,6 +1222,10 @@ 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);
diff --git a/mm/gup.c b/mm/gup.c
index a8521f1..01534ff 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -591,9 +591,9 @@ 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;
@@ -707,11 +707,37 @@ 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:
*
* down_read(&mm->mmap_sem);
@@ -732,14 +758,8 @@ 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);
@@ -803,7 +823,7 @@ 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);
diff --git a/mm/nommu.c b/mm/nommu.c
index 2a63d1f..6f6c752 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -223,9 +223,10 @@ 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,
- unsigned long start, unsigned long nr_pages,
- int write, int force, struct page **pages)
+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;
down_read(&mm->mmap_sem);
@@ -234,6 +235,15 @@ 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);
/**
--
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