Commit 2039e6ac authored by Toshi Kani's avatar Toshi Kani Committed by Thomas Gleixner
Browse files

x86/mm/pat: Change free_memtype() to support shrinking case 



Using mremap() to shrink the map size of a VM_PFNMAP range causes
the following error message, and leaves the pfn range allocated.

 x86/PAT: test:3493 freeing invalid memtype [mem 0x483200000-0x4863fffff]

This is because rbt_memtype_erase(), called from free_memtype()
with spin_lock held, only supports to free a whole memtype node in
memtype_rbroot.  Therefore, this patch changes rbt_memtype_erase()
to support a request that shrinks the size of a memtype node for
mremap().

memtype_rb_exact_match() is renamed to memtype_rb_match(), and
is enhanced to support EXACT_MATCH and END_MATCH in @match_type.
Since the memtype_rbroot tree allows overlapping ranges,
rbt_memtype_erase() checks with EXACT_MATCH first, i.e. free
a whole node for the munmap case.  If no such entry is found,
it then checks with END_MATCH, i.e. shrink the size of a node
from the end for the mremap case.

On the mremap case, rbt_memtype_erase() proceeds in two steps,
1) remove the node, and then 2) insert the updated node.  This
allows proper update of augmented values, subtree_max_end, in
the tree.

Signed-off-by: default avatarToshi Kani <toshi.kani@hpe.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: stsp@list.ru
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1450832064-10093-3-git-send-email-toshi.kani@hpe.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent d9fe4fab

arch/x86/mm/pat.c

+1 −1
Original line number Diff line number Diff line
@@ -586,7 +586,7 @@ int free_memtype(u64 start, u64 end) 
	entry = rbt_memtype_erase(start, end);

	spin_unlock(&memtype_lock);



	if (!entry) {

	if (IS_ERR(entry)) {

		pr_info("x86/PAT: %s:%d freeing invalid memtype [mem %#010Lx-%#010Lx]\n",

			current->comm, current->pid, start, end - 1);

		return -EINVAL;

arch/x86/mm/pat_rbtree.c

+43 −9
Original line number Diff line number Diff line
@@ -98,8 +98,13 @@ static struct memtype *memtype_rb_lowest_match(struct rb_root *root, 
	return last_lower; /* Returns NULL if there is no overlap */

}



static struct memtype *memtype_rb_exact_match(struct rb_root *root,

				u64 start, u64 end)

enum {

	MEMTYPE_EXACT_MATCH	= 0,

	MEMTYPE_END_MATCH	= 1

};



static struct memtype *memtype_rb_match(struct rb_root *root,

				u64 start, u64 end, int match_type)

{

	struct memtype *match;
@@ -107,7 +112,12 @@ static struct memtype *memtype_rb_exact_match(struct rb_root *root, 
	while (match != NULL && match->start < end) {

		struct rb_node *node;



		if (match->start == start && match->end == end)

		if ((match_type == MEMTYPE_EXACT_MATCH) &&

		    (match->start == start) && (match->end == end))

			return match;



		if ((match_type == MEMTYPE_END_MATCH) &&

		    (match->start < start) && (match->end == end))

			return match;



		node = rb_next(&match->rb);
@@ -117,7 +127,7 @@ static struct memtype *memtype_rb_exact_match(struct rb_root *root, 
			match = NULL;

	}



	return NULL; /* Returns NULL if there is no exact match */

	return NULL; /* Returns NULL if there is no match */

}



static int memtype_rb_check_conflict(struct rb_root *root,
@@ -210,12 +220,36 @@ struct memtype *rbt_memtype_erase(u64 start, u64 end) 
{

	struct memtype *data;



	data = memtype_rb_exact_match(&memtype_rbroot, start, end);

	/*

	 * Since the memtype_rbroot tree allows overlapping ranges,

	 * rbt_memtype_erase() checks with EXACT_MATCH first, i.e. free

	 * a whole node for the munmap case.  If no such entry is found,

	 * it then checks with END_MATCH, i.e. shrink the size of a node

	 * from the end for the mremap case.

	 */

	data = memtype_rb_match(&memtype_rbroot, start, end,

				MEMTYPE_EXACT_MATCH);

	if (!data) {

		data = memtype_rb_match(&memtype_rbroot, start, end,

					MEMTYPE_END_MATCH);

		if (!data)

		goto out;

			return ERR_PTR(-EINVAL);

	}



	if (data->start == start) {

		/* munmap: erase this node */

		rb_erase_augmented(&data->rb, &memtype_rbroot,

					&memtype_rb_augment_cb);

	} else {

		/* mremap: update the end value of this node */

		rb_erase_augmented(&data->rb, &memtype_rbroot,

					&memtype_rb_augment_cb);

		data->end = start;

		data->subtree_max_end = data->end;

		memtype_rb_insert(&memtype_rbroot, data);

		return NULL;

	}



	rb_erase_augmented(&data->rb, &memtype_rbroot, &memtype_rb_augment_cb);

out:

	return data;

}

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