Commit ecf371b2 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

mm: tweak __vma_enter_locked() 

Move the commentary on how __vma_enter_locked() behaves from the body of
__vma_start_write() to the head of __vma_enter_locked() and merge it with
the existing documentation.  Also add a call to
mmap_assert_write_locked().

Link: https://lkml.kernel.org/r/20251119042639.3937024-1-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 31807483

mm/mmap_lock.c

+5 −8
Original line number Diff line number Diff line
@@ -46,9 +46,9 @@ EXPORT_SYMBOL(__mmap_lock_do_trace_released); 
#ifdef CONFIG_MMU

#ifdef CONFIG_PER_VMA_LOCK

/*

 * Return value: 0 if vma detached,

 * 1 if vma attached with no readers,

 * -EINTR if signal received,

 * __vma_enter_locked() returns 0 immediately if the vma is not

 * attached, otherwise it waits for any current readers to finish and

 * returns 1.  Returns -EINTR if a signal is received while waiting.

 */

static inline int __vma_enter_locked(struct vm_area_struct *vma,

		bool detaching, int state)
@@ -56,6 +56,8 @@ static inline int __vma_enter_locked(struct vm_area_struct *vma, 
	int err;

	unsigned int tgt_refcnt = VMA_LOCK_OFFSET;



	mmap_assert_write_locked(vma->vm_mm);



	/* Additional refcnt if the vma is attached. */

	if (!detaching)

		tgt_refcnt++;
@@ -91,11 +93,6 @@ int __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq, 
{

	int locked;



	/*

	 * __vma_enter_locked() returns false immediately if the vma is not

	 * attached, otherwise it waits until refcnt is indicating that vma

	 * is attached with no readers.

	 */

	locked = __vma_enter_locked(vma, false, state);

	if (locked < 0)

		return locked;