Re: [PATCH 01/10] mm: remove write/force parameters from __get_user_pages_locked()

[Jan Kara]

On Thu 13-10-16 01:20:11, Lorenzo Stoakes wrote:
> This patch removes the write and force parameters from 
> __get_user_pages_locked()
> to make the use of FOLL_FORCE explicit in callers as use of this flag can 
> result
> in surprising behaviour (and hence bugs) within the mm subsystem.
> 
> Signed-off-by: Lorenzo Stoakes 

Looks good. You can add:

Reviewed-by: Jan Kara 

Honza
-- 
Jan Kara 
SUSE Labs, CR

Re: [PATCH 01/10] mm: remove write/force parameters from __get_user_pages_locked()

[Jan Kara]

On Thu 13-10-16 01:20:11, Lorenzo Stoakes wrote:
> This patch removes the write and force parameters from 
> __get_user_pages_locked()
> to make the use of FOLL_FORCE explicit in callers as use of this flag can 
> result
> in surprising behaviour (and hence bugs) within the mm subsystem.
> 
> Signed-off-by: Lorenzo Stoakes 

Looks good. You can add:

Reviewed-by: Jan Kara 

Honza
-- 
Jan Kara 
SUSE Labs, CR

[PATCH 01/10] mm: remove write/force parameters from __get_user_pages_locked()

[Lorenzo Stoakes]

This patch removes the write and force parameters from __get_user_pages_locked()
to make the use of FOLL_FORCE explicit in callers as use of this flag can result
in surprising behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes 
---
 mm/gup.c | 47 +--
 1 file changed, 33 insertions(+), 14 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 96b2b2f..ba83942 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -729,7 +729,6 @@ static __always_inline 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,
struct vm_area_struct **vmas,
int *locked, bool notify_drop,
@@ -747,10 +746,6 @@ static __always_inline long __get_user_pages_locked(struct 
task_struct *tsk,
 
if (pages)
flags |= FOLL_GET;
-   if (write)
-   flags |= FOLL_WRITE;
-   if (force)
-   flags |= FOLL_FORCE;
 
pages_done = 0;
lock_dropped = false;
@@ -846,9 +841,15 @@ long get_user_pages_locked(unsigned long start, unsigned 
long nr_pages,
   int write, int force, struct page **pages,
   int *locked)
 {
+   unsigned int flags = FOLL_TOUCH;
+
+   if (write)
+   flags |= FOLL_WRITE;
+   if (force)
+   flags |= FOLL_FORCE;
+
return __get_user_pages_locked(current, current->mm, start, nr_pages,
-  write, force, pages, NULL, locked, true,
-  FOLL_TOUCH);
+  pages, NULL, locked, true, flags);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 
@@ -869,9 +870,15 @@ __always_inline long __get_user_pages_unlocked(struct 
task_struct *tsk, struct m
 {
long ret;
int locked = 1;
+
+   if (write)
+   gup_flags |= FOLL_WRITE;
+   if (force)
+   gup_flags |= FOLL_FORCE;
+
down_read(>mmap_sem);
-   ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
- pages, NULL, , false, gup_flags);
+   ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL,
+ , false, gup_flags);
if (locked)
up_read(>mmap_sem);
return ret;
@@ -963,9 +970,15 @@ long get_user_pages_remote(struct task_struct *tsk, struct 
mm_struct *mm,
int write, 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,
-  FOLL_TOUCH | FOLL_REMOTE);
+   unsigned int flags = FOLL_TOUCH | FOLL_REMOTE;
+
+   if (write)
+   flags |= FOLL_WRITE;
+   if (force)
+   flags |= FOLL_FORCE;
+
+   return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
+  NULL, false, flags);
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
@@ -979,9 +992,15 @@ long get_user_pages(unsigned long start, unsigned long 
nr_pages,
int write, int force, struct page **pages,
struct vm_area_struct **vmas)
 {
+   unsigned int flags = FOLL_TOUCH;
+
+   if (write)
+   flags |= FOLL_WRITE;
+   if (force)
+   flags |= FOLL_FORCE;
+
return __get_user_pages_locked(current, current->mm, start, nr_pages,
-  write, force, pages, vmas, NULL, false,
-  FOLL_TOUCH);
+  pages, vmas, NULL, false, flags);
 }
 EXPORT_SYMBOL(get_user_pages);
 
-- 
2.10.0

[PATCH 01/10] mm: remove write/force parameters from __get_user_pages_locked()

[Lorenzo Stoakes]

This patch removes the write and force parameters from __get_user_pages_locked()
to make the use of FOLL_FORCE explicit in callers as use of this flag can result
in surprising behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes 
---
 mm/gup.c | 47 +--
 1 file changed, 33 insertions(+), 14 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 96b2b2f..ba83942 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -729,7 +729,6 @@ static __always_inline 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,
struct vm_area_struct **vmas,
int *locked, bool notify_drop,
@@ -747,10 +746,6 @@ static __always_inline long __get_user_pages_locked(struct 
task_struct *tsk,
 
if (pages)
flags |= FOLL_GET;
-   if (write)
-   flags |= FOLL_WRITE;
-   if (force)
-   flags |= FOLL_FORCE;
 
pages_done = 0;
lock_dropped = false;
@@ -846,9 +841,15 @@ long get_user_pages_locked(unsigned long start, unsigned 
long nr_pages,
   int write, int force, struct page **pages,
   int *locked)
 {
+   unsigned int flags = FOLL_TOUCH;
+
+   if (write)
+   flags |= FOLL_WRITE;
+   if (force)
+   flags |= FOLL_FORCE;
+
return __get_user_pages_locked(current, current->mm, start, nr_pages,
-  write, force, pages, NULL, locked, true,
-  FOLL_TOUCH);
+  pages, NULL, locked, true, flags);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 
@@ -869,9 +870,15 @@ __always_inline long __get_user_pages_unlocked(struct 
task_struct *tsk, struct m
 {
long ret;
int locked = 1;
+
+   if (write)
+   gup_flags |= FOLL_WRITE;
+   if (force)
+   gup_flags |= FOLL_FORCE;
+
down_read(>mmap_sem);
-   ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
- pages, NULL, , false, gup_flags);
+   ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL,
+ , false, gup_flags);
if (locked)
up_read(>mmap_sem);
return ret;
@@ -963,9 +970,15 @@ long get_user_pages_remote(struct task_struct *tsk, struct 
mm_struct *mm,
int write, 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,
-  FOLL_TOUCH | FOLL_REMOTE);
+   unsigned int flags = FOLL_TOUCH | FOLL_REMOTE;
+
+   if (write)
+   flags |= FOLL_WRITE;
+   if (force)
+   flags |= FOLL_FORCE;
+
+   return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
+  NULL, false, flags);
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
@@ -979,9 +992,15 @@ long get_user_pages(unsigned long start, unsigned long 
nr_pages,
int write, int force, struct page **pages,
struct vm_area_struct **vmas)
 {
+   unsigned int flags = FOLL_TOUCH;
+
+   if (write)
+   flags |= FOLL_WRITE;
+   if (force)
+   flags |= FOLL_FORCE;
+
return __get_user_pages_locked(current, current->mm, start, nr_pages,
-  write, force, pages, vmas, NULL, false,
-  FOLL_TOUCH);
+  pages, vmas, NULL, false, flags);
 }
 EXPORT_SYMBOL(get_user_pages);
 
-- 
2.10.0