mmap locking API: convert mmap_sem API comments

Convert comments that reference old mmap_sem APIs to reference
corresponding new mmap locking APIs instead.

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-12-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/vm/hmm.rst

@@ -191,15 +191,15 @@ The usage pattern is::
 
  again:
       range.notifier_seq = mmu_interval_read_begin(&interval_sub);
-      down_read(&mm->mmap_sem);
+      mmap_read_lock(mm);
       ret = hmm_range_fault(&range);
       if (ret) {
-          up_read(&mm->mmap_sem);
+          mmap_read_unlock(mm);
           if (ret == -EBUSY)
                  goto again;
           return ret;
       }
-      up_read(&mm->mmap_sem);
+      mmap_read_unlock(mm);
 
       take_lock(driver->update);
       if (mmu_interval_read_retry(&ni, range.notifier_seq) {

arch/alpha/mm/fault.c

@@ -171,7 +171,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 
-			 /* No need to up_read(&mm->mmap_sem) as we would
+			 /* No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/ia64/mm/fault.c

@@ -173,7 +173,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 
-			 /* No need to up_read(&mm->mmap_sem) as we would
+			 /* No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/m68k/mm/fault.c

@@ -165,7 +165,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 			flags |= FAULT_FLAG_TRIED;
 
 			/*
-			 * No need to up_read(&mm->mmap_sem) as we would
+			 * No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/microblaze/mm/fault.c

@@ -238,7 +238,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
 			flags |= FAULT_FLAG_TRIED;
 
 			/*
-			 * No need to up_read(&mm->mmap_sem) as we would
+			 * No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/mips/mm/fault.c

@@ -181,7 +181,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
 			flags |= FAULT_FLAG_TRIED;
 
 			/*
-			 * No need to up_read(&mm->mmap_sem) as we would
+			 * No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/nds32/mm/fault.c

@@ -247,7 +247,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 
-			/* No need to up_read(&mm->mmap_sem) as we would
+			/* No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/nios2/mm/fault.c

@@ -160,7 +160,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
 			flags |= FAULT_FLAG_TRIED;
 
 			/*
-			 * No need to up_read(&mm->mmap_sem) as we would
+			 * No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/openrisc/mm/fault.c

@@ -183,7 +183,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 
-			 /* No need to up_read(&mm->mmap_sem) as we would
+			 /* No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/parisc/mm/fault.c

@@ -329,7 +329,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
 			current->min_flt++;
 		if (fault & VM_FAULT_RETRY) {
 			/*
-			 * No need to up_read(&mm->mmap_sem) as we would
+			 * No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/riscv/mm/fault.c

@@ -147,7 +147,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
 			flags |= FAULT_FLAG_TRIED;
 
 			/*
-			 * No need to up_read(&mm->mmap_sem) as we would
+			 * No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/sh/mm/fault.c

@@ -502,7 +502,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 			flags |= FAULT_FLAG_TRIED;
 
 			/*
-			 * No need to up_read(&mm->mmap_sem) as we would
+			 * No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/sparc/mm/fault_32.c

@@ -262,7 +262,7 @@ asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 
-			/* No need to up_read(&mm->mmap_sem) as we would
+			/* No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/sparc/mm/fault_64.c

@@ -450,7 +450,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 
-			/* No need to up_read(&mm->mmap_sem) as we would
+			/* No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

arch/xtensa/mm/fault.c

@@ -130,7 +130,7 @@ void do_page_fault(struct pt_regs *regs)
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 
-			 /* No need to up_read(&mm->mmap_sem) as we would
+			 /* No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

drivers/android/binder_alloc.c

@@ -933,7 +933,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
 	if (!mmget_not_zero(mm))
 		goto err_mmget;
 	if (!mmap_read_trylock(mm))
-		goto err_down_read_mmap_sem_failed;
+		goto err_mmap_read_lock_failed;
 	vma = binder_alloc_get_vma(alloc);
 
 	list_lru_isolate(lru, item);
@@ -960,7 +960,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
 	mutex_unlock(&alloc->mutex);
 	return LRU_REMOVED_RETRY;
 
-err_down_read_mmap_sem_failed:
+err_mmap_read_lock_failed:
 	mmput_async(mm);
 err_mmget:
 err_page_already_freed:

fs/hugetlbfs/inode.c

@@ -187,7 +187,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 }
 
 /*
- * Called under down_write(mmap_sem).
+ * Called under mmap_write_lock(mm).
  */
 
 #ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA

fs/userfaultfd.c

@@ -1248,7 +1248,7 @@ static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
 	/*
 	 * To be sure waitqueue_active() is not reordered by the CPU
 	 * before the pagetable update, use an explicit SMP memory
-	 * barrier here. PT lock release or up_read(mmap_sem) still
+	 * barrier here. PT lock release or mmap_read_unlock(mm) still
 	 * have release semantics that can allow the
 	 * waitqueue_active() to be reordered before the pte update.
 	 */

mm/filemap.c

@@ -1373,7 +1373,7 @@ EXPORT_SYMBOL_GPL(__lock_page_killable);
  * Return values:
  * 1 - page is locked; mmap_sem is still held.
  * 0 - page is not locked.
- *     mmap_sem has been released (up_read()), unless flags had both
+ *     mmap_lock has been released (mmap_read_unlock(), unless flags had both
  *     FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
  *     which case mmap_sem is still held.
  *

mm/gup.c

@@ -1993,19 +1993,19 @@ EXPORT_SYMBOL(get_user_pages);
 /**
  * get_user_pages_locked() is suitable to replace the form:
  *
- *      down_read(&mm->mmap_sem);
+ *      mmap_read_lock(mm);
  *      do_something()
  *      get_user_pages(tsk, mm, ..., pages, NULL);
- *      up_read(&mm->mmap_sem);
+ *      mmap_read_unlock(mm);
  *
  *  to:
  *
  *      int locked = 1;
- *      down_read(&mm->mmap_sem);
+ *      mmap_read_lock(mm);
  *      do_something()
  *      get_user_pages_locked(tsk, mm, ..., pages, &locked);
  *      if (locked)
- *          up_read(&mm->mmap_sem);
+ *          mmap_read_unlock(mm);
  *
  * @start:      starting user address
  * @nr_pages:   number of pages from start to pin
@@ -2050,9 +2050,9 @@ EXPORT_SYMBOL(get_user_pages_locked);
 /*
  * get_user_pages_unlocked() is suitable to replace the form:
  *
- *      down_read(&mm->mmap_sem);
+ *      mmap_read_lock(mm);
  *      get_user_pages(tsk, mm, ..., pages, NULL);
- *      up_read(&mm->mmap_sem);
+ *      mmap_read_unlock(mm);
  *
  *  with:
  *

mm/huge_memory.c

@@ -1833,9 +1833,9 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 		goto unlock;
 
 	/*
-	 * In case prot_numa, we are under down_read(mmap_sem). It's critical
+	 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
 	 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
-	 * which is also under down_read(mmap_sem):
+	 * which is also under mmap_read_lock(mm):
 	 *
 	 *	CPU0:				CPU1:
 	 *				change_huge_pmd(prot_numa=1)

mm/khugepaged.c

@@ -1543,7 +1543,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
 		/*
 		 * Check vma->anon_vma to exclude MAP_PRIVATE mappings that
 		 * got written to. These VMAs are likely not worth investing
-		 * down_write(mmap_sem) as PMD-mapping is likely to be split
+		 * mmap_write_lock(mm) as PMD-mapping is likely to be split
 		 * later.
 		 *
 		 * Not that vma->anon_vma check is racy: it can be set up after

mm/ksm.c

@@ -2362,7 +2362,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
 	} else {
 		mmap_read_unlock(mm);
 		/*
-		 * up_read(&mm->mmap_sem) first because after
+		 * mmap_read_unlock(mm) first because after
 		 * spin_unlock(&ksm_mmlist_lock) run, the "mm" may
 		 * already have been freed under us by __ksm_exit()
 		 * because the "mm_slot" is still hashed and

mm/memory.c

@@ -3323,10 +3323,10 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	 * pte_offset_map() on pmds where a huge pmd might be created
 	 * from a different thread.
 	 *
-	 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
+	 * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
 	 * parallel threads are excluded by other means.
 	 *
-	 * Here we only have down_read(mmap_sem).
+	 * Here we only have mmap_read_lock(mm).
 	 */
 	if (pte_alloc(vma->vm_mm, vmf->pmd))
 		return VM_FAULT_OOM;

mm/mempolicy.c

@@ -2185,7 +2185,7 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
  *
  * 	This function allocates a page from the kernel page pool and applies
  *	a NUMA policy associated with the VMA or the current process.
- *	When VMA is not NULL caller must hold down_read on the mmap_sem of the
+ *	When VMA is not NULL caller must read-lock the mmap_lock of the
  *	mm_struct of the VMA to prevent it from going away. Should be used for
  *	all allocations for pages that will be mapped into user space. Returns
  *	NULL when no page can be allocated.

mm/migrate.c

@@ -2772,10 +2772,10 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
 	 * pte_offset_map() on pmds where a huge pmd might be created
 	 * from a different thread.
 	 *
-	 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
+	 * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
 	 * parallel threads are excluded by other means.
 	 *
-	 * Here we only have down_read(mmap_sem).
+	 * Here we only have mmap_read_lock(mm).
 	 */
 	if (pte_alloc(mm, pmdp))
 		goto abort;

mm/mmap.c

@@ -1361,7 +1361,7 @@ static inline bool file_mmap_ok(struct file *file, struct inode *inode,
 }
 
 /*
- * The caller must hold down_write(&current->mm->mmap_sem).
+ * The caller must write-lock current->mm->mmap_lock.
  */
 unsigned long do_mmap(struct file *file, unsigned long addr,
 			unsigned long len, unsigned long prot,

mm/oom_kill.c

@@ -577,8 +577,8 @@ static bool oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm)
 	/*
 	 * MMF_OOM_SKIP is set by exit_mmap when the OOM reaper can't
 	 * work on the mm anymore. The check for MMF_OOM_SKIP must run
-	 * under mmap_sem for reading because it serializes against the
-	 * down_write();up_write() cycle in exit_mmap().
+	 * under mmap_lock for reading because it serializes against the
+	 * mmap_write_lock();mmap_write_unlock() cycle in exit_mmap().
 	 */
 	if (test_bit(MMF_OOM_SKIP, &mm->flags)) {
 		trace_skip_task_reaping(tsk->pid);
@@ -611,7 +611,7 @@ static void oom_reap_task(struct task_struct *tsk)
 	int attempts = 0;
 	struct mm_struct *mm = tsk->signal->oom_mm;
 
-	/* Retry the down_read_trylock(mmap_sem) a few times */
+	/* Retry the mmap_read_trylock(mm) a few times */
 	while (attempts++ < MAX_OOM_REAP_RETRIES && !oom_reap_task_mm(tsk, mm))
 		schedule_timeout_idle(HZ/10);
 
@@ -629,7 +629,7 @@ static void oom_reap_task(struct task_struct *tsk)
 
 	/*
 	 * Hide this mm from OOM killer because it has been either reaped or
-	 * somebody can't call up_write(mmap_sem).
+	 * somebody can't call mmap_write_unlock(mm).
 	 */
 	set_bit(MMF_OOM_SKIP, &mm->flags);
 

net/ipv4/tcp.c

@@ -1734,7 +1734,7 @@ int tcp_mmap(struct file *file, struct socket *sock,
 		return -EPERM;
 	vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC);
 
-	/* Instruct vm_insert_page() to not down_read(mmap_sem) */
+	/* Instruct vm_insert_page() to not mmap_read_lock(mm) */
 	vma->vm_flags |= VM_MIXEDMAP;
 
 	vma->vm_ops = &tcp_vm_ops;