Re: [PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

Re: [PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

[youling 257]

I have build error about kernel/sys.c,


kernel/sys.c: In function ‘prctl_set_vma’:

kernel/sys.c:2392:18: error:

‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean

‘mmap_base’?

  2392 |  down_write(&mm->mmap_sem);

       |                  ^~~~~~~~

       |                  mmap_base

kernel/sys.c:2402:16: error:

‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean

‘mmap_base’?

  2402 |  up_write(&mm->mmap_sem);

       |                ^~~~~~~~

       |                mmap_base



why not rename kernel/sys.c mmap_sem to mmap_lock?


diff --git a/kernel/sys.c b/kernel/sys.c

index 113955fe1c6b..043c04a745a9 100644

--- a/kernel/sys.c

+++ b/kernel/sys.c

@@ -2389,7 +2389,7 @@ static int prctl_set_vma(unsigned long opt,
unsigned long start,

      if (end == start)

          return 0;

-    down_write(&mm->mmap_sem);

+    down_write(&mm->mmap_lock);

      switch (opt) {

      case PR_SET_VMA_ANON_NAME:

@@ -2399,7 +2399,7 @@ static int prctl_set_vma(unsigned long opt,
unsigned long start,

          error = -EINVAL;

      }

-    up_write(&mm->mmap_sem);

+    up_write(&mm->mmap_lock);

      return error;

  }

Re: [PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

[Michel Lespinasse]

On Wed, Jun 3, 2020 at 9:35 PM youling 257 <youling257@gmail.com> wrote:
> I have build error about kernel/sys.c,
>
> kernel/sys.c: In function ‘prctl_set_vma’:
> kernel/sys.c:2392:18: error:
> ‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean
> ‘mmap_base’?
>   2392 |  down_write(&mm->mmap_sem);
>        |                  ^~~~~~~~
>        |                  mmap_base
> kernel/sys.c:2402:16: error:
> ‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean
> ‘mmap_base’?
>   2402 |  up_write(&mm->mmap_sem);
>        |                ^~~~~~~~
>        |                mmap_base
>
> why not rename kernel/sys.c mmap_sem to mmap_lock?

The proper fix would be to use the mmap locking apis defined in
include/linux/mmap_lock.h instead.

However I would like more information about your report. Did you apply
the series yourself ? If so, what base tree did you apply it onto ? If
not, what tree did you use that already included the series ?

Thanks,

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.

Re: [PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

[youling 257]

i build linux next kernel have the kernel/sys.c error.

2020-06-04 13:57 GMT+08:00, Michel Lespinasse <walken@google.com>:
> On Wed, Jun 3, 2020 at 9:35 PM youling 257 <youling257@gmail.com> wrote:
>> I have build error about kernel/sys.c,
>>
>> kernel/sys.c: In function ‘prctl_set_vma’:
>> kernel/sys.c:2392:18: error:
>> ‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean
>> ‘mmap_base’?
>>   2392 |  down_write(&mm->mmap_sem);
>>        |                  ^~~~~~~~
>>        |                  mmap_base
>> kernel/sys.c:2402:16: error:
>> ‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean
>> ‘mmap_base’?
>>   2402 |  up_write(&mm->mmap_sem);
>>        |                ^~~~~~~~
>>        |                mmap_base
>>
>> why not rename kernel/sys.c mmap_sem to mmap_lock?
>
> The proper fix would be to use the mmap locking apis defined in
> include/linux/mmap_lock.h instead.
>
> However I would like more information about your report. Did you apply
> the series yourself ? If so, what base tree did you apply it onto ? If
> not, what tree did you use that already included the series ?
>
> Thanks,
>
> --
> Michel "Walken" Lespinasse
> A program is never fully debugged until the last user dies.
>

Re: [PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

[youling 257]

2020-06-04 13:57 GMT+08:00, Michel Lespinasse <walken@google.com>:
> On Wed, Jun 3, 2020 at 9:35 PM youling 257 <youling257@gmail.com> wrote:
>> I have build error about kernel/sys.c,
>>
>> kernel/sys.c: In function ‘prctl_set_vma’:
>> kernel/sys.c:2392:18: error:
>> ‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean
>> ‘mmap_base’?
>>   2392 |  down_write(&mm->mmap_sem);
>>        |                  ^~~~~~~~
>>        |                  mmap_base
>> kernel/sys.c:2402:16: error:
>> ‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean
>> ‘mmap_base’?
>>   2402 |  up_write(&mm->mmap_sem);
>>        |                ^~~~~~~~
>>        |                mmap_base
>>
>> why not rename kernel/sys.c mmap_sem to mmap_lock?
>
> The proper fix would be to use the mmap locking apis defined in
> include/linux/mmap_lock.h instead.
>
> However I would like more information about your report. Did you apply
> the series yourself ? If so, what base tree did you apply it onto ? If
> not, what tree did you use that already included the series ?

I build linux next-20200603 tree have the kernel/sys.c error.

> Thanks,
>
> --
> Michel "Walken" Lespinasse
> A program is never fully debugged until the last user dies.
>

Re: [PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

[Michel Lespinasse]

On Thu, Jun 4, 2020 at 1:16 AM youling 257 <youling257@gmail.com> wrote:
> 2020-06-04 13:57 GMT+08:00, Michel Lespinasse <walken@google.com>:
> > However I would like more information about your report. Did you apply
> > the series yourself ? If so, what base tree did you apply it onto ? If
> > not, what tree did you use that already included the series ?
>
> I build linux next-20200603 tree have the kernel/sys.c error.

Thanks for the info.

The proper fix is to replace down_write(&mm->mmap_sem) with
mmap_write_lock(mm) and up_write(&mm->mmap_sem) with
mmap_write_unlock(mm)

If you just needed a quick fix to get the tree to build, what you did
(replacing mmap_sem with mmap_lock) is also fine.

Thanks again !

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.

Re: [PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

[youling 257]

today test linux kernel master branch, I have kernel/sys.c build error.
can you make a fix patch and push to linus?

2020-06-04 16:38 GMT+08:00, Michel Lespinasse <walken@google.com>:
> On Thu, Jun 4, 2020 at 1:16 AM youling 257 <youling257@gmail.com> wrote:
>> 2020-06-04 13:57 GMT+08:00, Michel Lespinasse <walken@google.com>:
>> > However I would like more information about your report. Did you apply
>> > the series yourself ? If so, what base tree did you apply it onto ? If
>> > not, what tree did you use that already included the series ?
>>
>> I build linux next-20200603 tree have the kernel/sys.c error.
>
> Thanks for the info.
>
> The proper fix is to replace down_write(&mm->mmap_sem) with
> mmap_write_lock(mm) and up_write(&mm->mmap_sem) with
> mmap_write_unlock(mm)
>
> If you just needed a quick fix to get the tree to build, what you did
> (replacing mmap_sem with mmap_lock) is also fine.
>
> Thanks again !
>
> --
> Michel "Walken" Lespinasse
> A program is never fully debugged until the last user dies.
>

Re: [PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

[Daniel Jordan]

On Tue, May 19, 2020 at 10:29:06PM -0700, Michel Lespinasse wrote:
> Rename the mmap_sem field to mmap_lock. Any new uses of this lock
> should now go through the new mmap locking api. The mmap_lock is
> still implemented as a rwsem, though this could change in the future.
> 
> Signed-off-by: Michel Lespinasse <walken@google.com>
> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>

Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>

Re: [PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

[Davidlohr Bueso]

On Tue, 19 May 2020, Michel Lespinasse wrote:

>Rename the mmap_sem field to mmap_lock. Any new uses of this lock
>should now go through the new mmap locking api. The mmap_lock is
>still implemented as a rwsem, though this could change in the future.
>
>Signed-off-by: Michel Lespinasse <walken@google.com>
>Reviewed-by: Vlastimil Babka <vbabka@suse.cz>

Reviewed-by: Davidlohr Bueso <dbueso@suse.de>

[PATCH v6 10/12] mmap locking API: rename mmap_sem to mmap_lock

[Michel Lespinasse]

Rename the mmap_sem field to mmap_lock. Any new uses of this lock
should now go through the new mmap locking api. The mmap_lock is
still implemented as a rwsem, though this could change in the future.

Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
---
 arch/ia64/mm/fault.c                  |  4 +--
 arch/x86/mm/fault.c                   |  2 +-
 drivers/gpu/drm/etnaviv/etnaviv_gem.c |  2 +-
 include/linux/mm_types.h              |  2 +-
 include/linux/mmap_lock.h             | 38 +++++++++++++--------------
 mm/memory.c                           |  2 +-
 mm/mmap.c                             |  4 +--
 mm/mmu_notifier.c                     |  2 +-
 8 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 693f00b117e1..9b95050c2048 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -70,8 +70,8 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
 	mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
 		| (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
 
-	/* mmap_sem is performance critical.... */
-	prefetchw(&mm->mmap_sem);
+	/* mmap_lock is performance critical.... */
+	prefetchw(&mm->mmap_lock);
 
 	/*
 	 * If we're in an interrupt or have no user context, we must not take the fault..
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 181f66b9049f..35f530f9dfc0 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1522,7 +1522,7 @@ dotraplinkage void
 do_page_fault(struct pt_regs *regs, unsigned long hw_error_code,
 		unsigned long address)
 {
-	prefetchw(&current->mm->mmap_sem);
+	prefetchw(&current->mm->mmap_lock);
 	trace_page_fault_entries(regs, hw_error_code, address);
 
 	if (unlikely(kmmio_fault(regs, address)))
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index dc9ef302f517..701f3995f621 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -661,7 +661,7 @@ static int etnaviv_gem_userptr_get_pages(struct etnaviv_gem_object *etnaviv_obj)
 	struct etnaviv_gem_userptr *userptr = &etnaviv_obj->userptr;
 	int ret, pinned = 0, npages = etnaviv_obj->base.size >> PAGE_SHIFT;
 
-	might_lock_read(&current->mm->mmap_sem);
+	might_lock_read(&current->mm->mmap_lock);
 
 	if (userptr->mm != current->mm)
 		return -EPERM;
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 4aba6c0c2ba8..d13b90399c16 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -436,7 +436,7 @@ struct mm_struct {
 		spinlock_t page_table_lock; /* Protects page tables and some
 					     * counters
 					     */
-		struct rw_semaphore mmap_sem;
+		struct rw_semaphore mmap_lock;
 
 		struct list_head mmlist; /* List of maybe swapped mm's.	These
 					  * are globally strung together off
diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index 43ef914e6468..b5bd86778cca 100644
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -4,67 +4,67 @@
 #include <linux/mmdebug.h>
 
 #define MMAP_LOCK_INITIALIZER(name) \
-	.mmap_sem = __RWSEM_INITIALIZER((name).mmap_sem),
+	.mmap_lock = __RWSEM_INITIALIZER((name).mmap_lock),
 
 static inline void mmap_init_lock(struct mm_struct *mm)
 {
-	init_rwsem(&mm->mmap_sem);
+	init_rwsem(&mm->mmap_lock);
 }
 
 static inline void mmap_write_lock(struct mm_struct *mm)
 {
-	down_write(&mm->mmap_sem);
+	down_write(&mm->mmap_lock);
 }
 
 static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
 {
-	down_write_nested(&mm->mmap_sem, subclass);
+	down_write_nested(&mm->mmap_lock, subclass);
 }
 
 static inline int mmap_write_lock_killable(struct mm_struct *mm)
 {
-	return down_write_killable(&mm->mmap_sem);
+	return down_write_killable(&mm->mmap_lock);
 }
 
 static inline bool mmap_write_trylock(struct mm_struct *mm)
 {
-	return down_write_trylock(&mm->mmap_sem) != 0;
+	return down_write_trylock(&mm->mmap_lock) != 0;
 }
 
 static inline void mmap_write_unlock(struct mm_struct *mm)
 {
-	up_write(&mm->mmap_sem);
+	up_write(&mm->mmap_lock);
 }
 
 static inline void mmap_write_downgrade(struct mm_struct *mm)
 {
-	downgrade_write(&mm->mmap_sem);
+	downgrade_write(&mm->mmap_lock);
 }
 
 static inline void mmap_read_lock(struct mm_struct *mm)
 {
-	down_read(&mm->mmap_sem);
+	down_read(&mm->mmap_lock);
 }
 
 static inline int mmap_read_lock_killable(struct mm_struct *mm)
 {
-	return down_read_killable(&mm->mmap_sem);
+	return down_read_killable(&mm->mmap_lock);
 }
 
 static inline bool mmap_read_trylock(struct mm_struct *mm)
 {
-	return down_read_trylock(&mm->mmap_sem) != 0;
+	return down_read_trylock(&mm->mmap_lock) != 0;
 }
 
 static inline void mmap_read_unlock(struct mm_struct *mm)
 {
-	up_read(&mm->mmap_sem);
+	up_read(&mm->mmap_lock);
 }
 
 static inline bool mmap_read_trylock_non_owner(struct mm_struct *mm)
 {
-	if (down_read_trylock(&mm->mmap_sem)) {
-		rwsem_release(&mm->mmap_sem.dep_map, _RET_IP_);
+	if (down_read_trylock(&mm->mmap_lock)) {
+		rwsem_release(&mm->mmap_lock.dep_map, _RET_IP_);
 		return true;
 	}
 	return false;
@@ -72,19 +72,19 @@ static inline bool mmap_read_trylock_non_owner(struct mm_struct *mm)
 
 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
 {
-	up_read_non_owner(&mm->mmap_sem);
+	up_read_non_owner(&mm->mmap_lock);
 }
 
 static inline void mmap_assert_locked(struct mm_struct *mm)
 {
-	lockdep_assert_held(&mm->mmap_sem);
-	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+	lockdep_assert_held(&mm->mmap_lock);
+	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
 }
 
 static inline void mmap_assert_write_locked(struct mm_struct *mm)
 {
-	lockdep_assert_held_write(&mm->mmap_sem);
-	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+	lockdep_assert_held_write(&mm->mmap_lock);
+	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
 }
 
 #endif /* _LINUX_MMAP_LOCK_H */
diff --git a/mm/memory.c b/mm/memory.c
index 20f98ea8968e..c2963e7affa9 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4811,7 +4811,7 @@ void __might_fault(const char *file, int line)
 	__might_sleep(file, line, 0);
 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
 	if (current->mm)
-		might_lock_read(&current->mm->mmap_sem);
+		might_lock_read(&current->mm->mmap_lock);
 #endif
 }
 EXPORT_SYMBOL(__might_fault);
diff --git a/mm/mmap.c b/mm/mmap.c
index 2f4ffccc5972..80a47031d5db 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3474,7 +3474,7 @@ static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
 		 * The LSB of head.next can't change from under us
 		 * because we hold the mm_all_locks_mutex.
 		 */
-		down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
+		down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock);
 		/*
 		 * We can safely modify head.next after taking the
 		 * anon_vma->root->rwsem. If some other vma in this mm shares
@@ -3504,7 +3504,7 @@ static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
 		 */
 		if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
 			BUG();
-		down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
+		down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock);
 	}
 }
 
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 24eb9d1ed0a7..2f348b6c9c9a 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -983,7 +983,7 @@ int mmu_interval_notifier_insert(struct mmu_interval_notifier *interval_sub,
 	struct mmu_notifier_subscriptions *subscriptions;
 	int ret;
 
-	might_lock(&mm->mmap_sem);
+	might_lock(&mm->mmap_lock);
 
 	subscriptions = smp_load_acquire(&mm->notifier_subscriptions);
 	if (!subscriptions || !subscriptions->has_itree) {
-- 
2.26.2.761.g0e0b3e54be-goog