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Commit 1756954c authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm: fix build warning for uninitialized value 



do_wp_page() sets mmun_called if mmun_start and mmun_end were
initialized and, if so, may call mmu_notifier_invalidate_range_end()
with these values.  This doesn't prevent gcc from emitting a build
warning though:

  mm/memory.c: In function `do_wp_page':
  mm/memory.c:2530: warning: `mmun_start' may be used uninitialized in this function
  mm/memory.c:2531: warning: `mmun_end' may be used uninitialized in this function

It's much easier to initialize the variables to impossible values and do
a simple comparison to determine if they were initialized to remove the
bool entirely.

Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 63c3b902

mm/memory.c

+4 −6
Original line number Diff line number Diff line
@@ -2527,9 +2527,8 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 
	int ret = 0;

	int page_mkwrite = 0;

	struct page *dirty_page = NULL;

	unsigned long mmun_start;	/* For mmu_notifiers */

	unsigned long mmun_end;		/* For mmu_notifiers */

	bool mmun_called = false;	/* For mmu_notifiers */

	unsigned long mmun_start = 0;	/* For mmu_notifiers */

	unsigned long mmun_end = 0;	/* For mmu_notifiers */



	old_page = vm_normal_page(vma, address, orig_pte);

	if (!old_page) {
@@ -2708,8 +2707,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 
		goto oom_free_new;



	mmun_start  = address & PAGE_MASK;

	mmun_end    = (address & PAGE_MASK) + PAGE_SIZE;

	mmun_called = true;

	mmun_end    = mmun_start + PAGE_SIZE;

	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);



	/*
@@ -2778,7 +2776,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 
		page_cache_release(new_page);

unlock:

	pte_unmap_unlock(page_table, ptl);

	if (mmun_called)

	if (mmun_end > mmun_start)

		mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);

	if (old_page) {

		/*