The macro version of mmu_notifier_range_init() for CONFIG_MMU_NOTIFIER=n
does not evaluate all its arguments, leading to a warning in one case:
mm/migrate.c: In function 'migrate_vma_pages':
mm/migrate.c:2711:20: error: unused variable 'mm' [-Werror=unused-variable]
struct mm_struct *mm = vma->vm_mm;
Pass down the 'mm' as into the inline function as well so gcc can
see why the variable exists.
Fixes: 137d92bd73b1 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2")
Signed-off-by: Arnd Bergmann <[email protected]>
---
include/linux/mmu_notifier.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 29f7b9670ba3..b13ea00ded5d 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -476,6 +476,7 @@ struct mmu_notifier_range {
};
static inline void _mmu_notifier_range_init(struct mmu_notifier_range *range,
+ struct mm_struct *mm,
unsigned long start,
unsigned long end)
{
@@ -484,7 +485,7 @@ static inline void _mmu_notifier_range_init(struct mmu_notifier_range *range,
}
#define mmu_notifier_range_init(range, mm, start, end, event) \
- _mmu_notifier_range_init(range, start, end)
+ _mmu_notifier_range_init(range, mm, start, end)
static inline int mm_has_notifiers(struct mm_struct *mm)
--
2.20.0
On Tue, Dec 11, 2018 at 09:04:43PM +0100, Arnd Bergmann wrote:
> The macro version of mmu_notifier_range_init() for CONFIG_MMU_NOTIFIER=n
> does not evaluate all its arguments, leading to a warning in one case:
>
> mm/migrate.c: In function 'migrate_vma_pages':
> mm/migrate.c:2711:20: error: unused variable 'mm' [-Werror=unused-variable]
> struct mm_struct *mm = vma->vm_mm;
>
> Pass down the 'mm' as into the inline function as well so gcc can
> see why the variable exists.
>
> Fixes: 137d92bd73b1 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2")
What about changing migrate.c (i actualy tried to do that everywhere in
the patchset but i missed that spot) So we avoid one useless variable on
such configuration:
diff --git a/mm/migrate.c b/mm/migrate.c
index f02bb4b22c1a..883fce631f47 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2701,7 +2701,6 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
const unsigned long npages = migrate->npages;
const unsigned long start = migrate->start;
struct vm_area_struct *vma = migrate->vma;
- struct mm_struct *mm = vma->vm_mm;
struct mmu_notifier_range range;
unsigned long addr, i;
bool notified = false;
@@ -2724,8 +2723,8 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
if (!notified) {
notified = true;
- mmu_notifier_range_init(&range, mm, addr,
- migrate->end,
+ mmu_notifier_range_init(&range, vma->vm_mm,
+ addr, migrate->end,
MMU_NOTIFY_CLEAR);
mmu_notifier_invalidate_range_start(&range);
}
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> include/linux/mmu_notifier.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
> index 29f7b9670ba3..b13ea00ded5d 100644
> --- a/include/linux/mmu_notifier.h
> +++ b/include/linux/mmu_notifier.h
> @@ -476,6 +476,7 @@ struct mmu_notifier_range {
> };
>
> static inline void _mmu_notifier_range_init(struct mmu_notifier_range *range,
> + struct mm_struct *mm,
> unsigned long start,
> unsigned long end)
> {
> @@ -484,7 +485,7 @@ static inline void _mmu_notifier_range_init(struct mmu_notifier_range *range,
> }
>
> #define mmu_notifier_range_init(range, mm, start, end, event) \
> - _mmu_notifier_range_init(range, start, end)
> + _mmu_notifier_range_init(range, mm, start, end)
>
>
> static inline int mm_has_notifiers(struct mm_struct *mm)
> --
> 2.20.0
>
On Tue, 11 Dec 2018, Jerome Glisse wrote:
> On Tue, Dec 11, 2018 at 09:04:43PM +0100, Arnd Bergmann wrote:
> > The macro version of mmu_notifier_range_init() for CONFIG_MMU_NOTIFIER=n
> > does not evaluate all its arguments, leading to a warning in one case:
> >
> > mm/migrate.c: In function 'migrate_vma_pages':
> > mm/migrate.c:2711:20: error: unused variable 'mm' [-Werror=unused-variable]
> > struct mm_struct *mm = vma->vm_mm;
> >
> > Pass down the 'mm' as into the inline function as well so gcc can
> > see why the variable exists.
> >
> > Fixes: 137d92bd73b1 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2")
>
> What about changing migrate.c (i actualy tried to do that everywhere in
> the patchset but i missed that spot) So we avoid one useless variable on
> such configuration:
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index f02bb4b22c1a..883fce631f47 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2701,7 +2701,6 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
> const unsigned long npages = migrate->npages;
> const unsigned long start = migrate->start;
> struct vm_area_struct *vma = migrate->vma;
> - struct mm_struct *mm = vma->vm_mm;
> struct mmu_notifier_range range;
> unsigned long addr, i;
> bool notified = false;
> @@ -2724,8 +2723,8 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
> if (!notified) {
> notified = true;
>
> - mmu_notifier_range_init(&range, mm, addr,
> - migrate->end,
> + mmu_notifier_range_init(&range, vma->vm_mm,
> + addr, migrate->end,
> MMU_NOTIFY_CLEAR);
> mmu_notifier_invalidate_range_start(&range);
> }
Wouldn't it be better to just declare mmu_notifier_range_init() as a
static inline function rather than a #define to avoid this warning?
On Tue, Dec 11, 2018 at 01:12:54PM -0800, David Rientjes wrote:
> On Tue, 11 Dec 2018, Jerome Glisse wrote:
>
> > On Tue, Dec 11, 2018 at 09:04:43PM +0100, Arnd Bergmann wrote:
> > > The macro version of mmu_notifier_range_init() for CONFIG_MMU_NOTIFIER=n
> > > does not evaluate all its arguments, leading to a warning in one case:
> > >
> > > mm/migrate.c: In function 'migrate_vma_pages':
> > > mm/migrate.c:2711:20: error: unused variable 'mm' [-Werror=unused-variable]
> > > struct mm_struct *mm = vma->vm_mm;
> > >
> > > Pass down the 'mm' as into the inline function as well so gcc can
> > > see why the variable exists.
> > >
> > > Fixes: 137d92bd73b1 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2")
> >
> > What about changing migrate.c (i actualy tried to do that everywhere in
> > the patchset but i missed that spot) So we avoid one useless variable on
> > such configuration:
> >
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index f02bb4b22c1a..883fce631f47 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -2701,7 +2701,6 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
> > const unsigned long npages = migrate->npages;
> > const unsigned long start = migrate->start;
> > struct vm_area_struct *vma = migrate->vma;
> > - struct mm_struct *mm = vma->vm_mm;
> > struct mmu_notifier_range range;
> > unsigned long addr, i;
> > bool notified = false;
> > @@ -2724,8 +2723,8 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
> > if (!notified) {
> > notified = true;
> >
> > - mmu_notifier_range_init(&range, mm, addr,
> > - migrate->end,
> > + mmu_notifier_range_init(&range, vma->vm_mm,
> > + addr, migrate->end,
> > MMU_NOTIFY_CLEAR);
> > mmu_notifier_invalidate_range_start(&range);
> > }
>
> Wouldn't it be better to just declare mmu_notifier_range_init() as a
> static inline function rather than a #define to avoid this warning?
The define trick is use to drop the event parameter so that we do not
need to define the event value for CONFIG_MMU_NOTIFIER=n case.
Cheers,
J?r?me
On Tue, 11 Dec 2018, Jerome Glisse wrote:
> > > > The macro version of mmu_notifier_range_init() for CONFIG_MMU_NOTIFIER=n
> > > > does not evaluate all its arguments, leading to a warning in one case:
> > > >
> > > > mm/migrate.c: In function 'migrate_vma_pages':
> > > > mm/migrate.c:2711:20: error: unused variable 'mm' [-Werror=unused-variable]
> > > > struct mm_struct *mm = vma->vm_mm;
> > > >
> > > > Pass down the 'mm' as into the inline function as well so gcc can
> > > > see why the variable exists.
> > > >
> > > > Fixes: 137d92bd73b1 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2")
> > >
> > > What about changing migrate.c (i actualy tried to do that everywhere in
> > > the patchset but i missed that spot) So we avoid one useless variable on
> > > such configuration:
> > >
> > > diff --git a/mm/migrate.c b/mm/migrate.c
> > > index f02bb4b22c1a..883fce631f47 100644
> > > --- a/mm/migrate.c
> > > +++ b/mm/migrate.c
> > > @@ -2701,7 +2701,6 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
> > > const unsigned long npages = migrate->npages;
> > > const unsigned long start = migrate->start;
> > > struct vm_area_struct *vma = migrate->vma;
> > > - struct mm_struct *mm = vma->vm_mm;
> > > struct mmu_notifier_range range;
> > > unsigned long addr, i;
> > > bool notified = false;
> > > @@ -2724,8 +2723,8 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
> > > if (!notified) {
> > > notified = true;
> > >
> > > - mmu_notifier_range_init(&range, mm, addr,
> > > - migrate->end,
> > > + mmu_notifier_range_init(&range, vma->vm_mm,
> > > + addr, migrate->end,
> > > MMU_NOTIFY_CLEAR);
> > > mmu_notifier_invalidate_range_start(&range);
> > > }
> >
> > Wouldn't it be better to just declare mmu_notifier_range_init() as a
> > static inline function rather than a #define to avoid this warning?
>
> The define trick is use to drop the event parameter so that we do not
> need to define the event value for CONFIG_MMU_NOTIFIER=n case.
>
Hmm, strange that Arnd's build failure is only reporting about an unused
variable instead of MMU_NOTIFY_CLEAR being undefined :/
I think this should be done so that anybody using
mmu_notifier_range_init() doesn't need to worry about the implications of
*any* unused formal parameter as a result of how the #define is formed:
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -10,21 +10,6 @@
struct mmu_notifier;
struct mmu_notifier_ops;
-#ifdef CONFIG_MMU_NOTIFIER
-
-/*
- * The mmu notifier_mm structure is allocated and installed in
- * mm->mmu_notifier_mm inside the mm_take_all_locks() protected
- * critical section and it's released only when mm_count reaches zero
- * in mmdrop().
- */
-struct mmu_notifier_mm {
- /* all mmu notifiers registerd in this mm are queued in this list */
- struct hlist_head list;
- /* to serialize the list modifications and hlist_unhashed */
- spinlock_t lock;
-};
-
/**
* enum mmu_notifier_event - reason for the mmu notifier callback
* @MMU_NOTIFY_UNMAP: either munmap() that unmap the range or a mremap() that
@@ -53,6 +38,21 @@ enum mmu_notifier_event {
MMU_NOTIFY_SOFT_DIRTY,
};
+#ifdef CONFIG_MMU_NOTIFIER
+
+/*
+ * The mmu notifier_mm structure is allocated and installed in
+ * mm->mmu_notifier_mm inside the mm_take_all_locks() protected
+ * critical section and it's released only when mm_count reaches zero
+ * in mmdrop().
+ */
+struct mmu_notifier_mm {
+ /* all mmu notifiers registerd in this mm are queued in this list */
+ struct hlist_head list;
+ /* to serialize the list modifications and hlist_unhashed */
+ spinlock_t lock;
+};
+
struct mmu_notifier_range {
struct mm_struct *mm;
unsigned long start;
@@ -483,9 +483,14 @@ static inline void _mmu_notifier_range_init(struct mmu_notifier_range *range,
range->end = end;
}
-#define mmu_notifier_range_init(range, mm, start, end, event) \
- _mmu_notifier_range_init(range, start, end)
-
+static inline void mmu_notifier_range_init(struct mmu_notifier_range *range,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end,
+ enum mmu_notifier_event event)
+{
+ _mmu_notifier_range_init(range, start, end);
+}
static inline int mm_has_notifiers(struct mm_struct *mm)
{
On Tue, Dec 11, 2018 at 10:43 PM David Rientjes <[email protected]> wrote:
>
> On Tue, 11 Dec 2018, Jerome Glisse wrote:
>
> Hmm, strange that Arnd's build failure is only reporting about an unused
> variable instead of MMU_NOTIFY_CLEAR being undefined :/
>
> I think this should be done so that anybody using
> mmu_notifier_range_init() doesn't need to worry about the implications of
> *any* unused formal parameter as a result of how the #define is formed:
Your patch below is more or less what I tried at first, and that resulted
in another build failure for
mm/hugetlb.c: mmu_notifier_range_init(&range, mm, start, end,
MMU_NOTIFY_CLEAR);
mm/hugetlb.c- adjust_range_if_pmd_sharing_possible(vma,
&range.start, &range.end);
where range.end refers to a nonexisting member of range.
Arnd
On Tue, Dec 11, 2018 at 10:53:03PM +0100, Arnd Bergmann wrote:
> On Tue, Dec 11, 2018 at 10:43 PM David Rientjes <[email protected]> wrote:
> >
> > On Tue, 11 Dec 2018, Jerome Glisse wrote:
>
> >
> > Hmm, strange that Arnd's build failure is only reporting about an unused
> > variable instead of MMU_NOTIFY_CLEAR being undefined :/
> >
> > I think this should be done so that anybody using
> > mmu_notifier_range_init() doesn't need to worry about the implications of
> > *any* unused formal parameter as a result of how the #define is formed:
>
> Your patch below is more or less what I tried at first, and that resulted
> in another build failure for
>
> mm/hugetlb.c: mmu_notifier_range_init(&range, mm, start, end,
> MMU_NOTIFY_CLEAR);
> mm/hugetlb.c- adjust_range_if_pmd_sharing_possible(vma,
> &range.start, &range.end);
>
> where range.end refers to a nonexisting member of range.
>
> Arnd
I will post a v3 with htmldoc fix and build warning fix incorporated.
Cheers,
J?r?me
On Tue, 11 Dec 2018, Arnd Bergmann wrote:
> > Hmm, strange that Arnd's build failure is only reporting about an unused
> > variable instead of MMU_NOTIFY_CLEAR being undefined :/
> >
> > I think this should be done so that anybody using
> > mmu_notifier_range_init() doesn't need to worry about the implications of
> > *any* unused formal parameter as a result of how the #define is formed:
>
> Your patch below is more or less what I tried at first, and that resulted
> in another build failure for
>
> mm/hugetlb.c: mmu_notifier_range_init(&range, mm, start, end,
> MMU_NOTIFY_CLEAR);
> mm/hugetlb.c- adjust_range_if_pmd_sharing_possible(vma,
> &range.start, &range.end);
>
> where range.end refers to a nonexisting member of range.
>
Isn't that separate? It seems like there is a strict dependency that
CONFIG_HUGETLBFS has on CONFIG_MMU_NOTIFIER.