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Commit 5a0768f6 authored by Michel Lespinasse's avatar Michel Lespinasse Committed by Linus Torvalds
Browse files

mm: check rb_subtree_gap correctness 



When CONFIG_DEBUG_VM_RB is enabled, check that rb_subtree_gap is correctly
set for every vma and that mm->highest_vm_end is also correct.

Also add an explicit 'bug' variable to track if browse_rb() detected any
invalid condition.

[akpm@linux-foundation.org: repair innovative coding-style inventions]
Signed-off-by: default avatarMichel Lespinasse <walken@google.com>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d3737187

mm/mmap.c

+39 −14
Original line number Diff line number Diff line
@@ -322,31 +322,45 @@ static long vma_compute_subtree_gap(struct vm_area_struct *vma) 
#ifdef CONFIG_DEBUG_VM_RB

static int browse_rb(struct rb_root *root)

{

	int i = 0, j;

	int i = 0, j, bug = 0;

	struct rb_node *nd, *pn = NULL;

	unsigned long prev = 0, pend = 0;



	for (nd = rb_first(root); nd; nd = rb_next(nd)) {

		struct vm_area_struct *vma;

		vma = rb_entry(nd, struct vm_area_struct, vm_rb);

		if (vma->vm_start < prev)

			printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;

		if (vma->vm_start < pend)

		if (vma->vm_start < prev) {

			printk("vm_start %lx prev %lx\n", vma->vm_start, prev);

			bug = 1;

		}

		if (vma->vm_start < pend) {

			printk("vm_start %lx pend %lx\n", vma->vm_start, pend);

		if (vma->vm_start > vma->vm_end)

			printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);

			bug = 1;

		}

		if (vma->vm_start > vma->vm_end) {

			printk("vm_end %lx < vm_start %lx\n",

				vma->vm_end, vma->vm_start);

			bug = 1;

		}

		if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {

			printk("free gap %lx, correct %lx\n",

			       vma->rb_subtree_gap,

			       vma_compute_subtree_gap(vma));

			bug = 1;

		}

		i++;

		pn = nd;

		prev = vma->vm_start;

		pend = vma->vm_end;

	}

	j = 0;

	for (nd = pn; nd; nd = rb_prev(nd)) {

	for (nd = pn; nd; nd = rb_prev(nd))

		j++;

	if (i != j) {

		printk("backwards %d, forwards %d\n", j, i);

		bug = 1;

	}

	if (i != j)

		printk("backwards %d, forwards %d\n", j, i), i = 0;

	return i;

	return bug ? -1 : i;

}



static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
@@ -365,6 +379,7 @@ void validate_mm(struct mm_struct *mm) 
{

	int bug = 0;

	int i = 0;

	unsigned long highest_address = 0;

	struct vm_area_struct *vma = mm->mmap;

	while (vma) {

		struct anon_vma_chain *avc;
@@ -372,14 +387,24 @@ void validate_mm(struct mm_struct *mm) 
		list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)

			anon_vma_interval_tree_verify(avc);

		vma_unlock_anon_vma(vma);

		highest_address = vma->vm_end;

		vma = vma->vm_next;

		i++;

	}

	if (i != mm->map_count)

		printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;

	if (i != mm->map_count) {

		printk("map_count %d vm_next %d\n", mm->map_count, i);

		bug = 1;

	}

	if (highest_address != mm->highest_vm_end) {

		printk("mm->highest_vm_end %lx, found %lx\n",

		       mm->highest_vm_end, highest_address);

		bug = 1;

	}

	i = browse_rb(&mm->mm_rb);

	if (i != mm->map_count)

		printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;

	if (i != mm->map_count) {

		printk("map_count %d rb %d\n", mm->map_count, i);

		bug = 1;

	}

	BUG_ON(bug);

}

#else