Skip to main content

Browse the archive

Revision 475049809977bf3975d78f2d2fd992e19ce2d59e authored by Roel Kluin on 10 March 2009, 19:55:45 UTC, committed by Linus Torvalds on 10 March 2009, 22:55:10 UTC 
mm: get_nid_for_pfn() returns int
 
get_nid_for_pfn() returns int

Presumably the (nid < 0) case has never happened.

We do know that it is happening on one system while creating a symlink for
a memory section so it should also happen on the same system if
unregister_mem_sect_under_nodes() were called to remove the same symlink.

The test was actually added in response to a problem with an earlier
version reported by Yasunori Goto where one or more of the leading pages
of a memory section on the 2nd node of one of his systems was
uninitialized because I believe they coincided with a memory hole.

That earlier version did not ignore uninitialized pages and determined
the nid by considering only the 1st page of each memory section.  This
caused the symlink to the 1st memory section on the 2nd node to be
incorrectly created in /sys/devices/system/node/node0 instead of
/sys/devices/system/node/node1.  The problem was fixed by adding the
test to skip over uninitialized pages.

I suspect we have not seen any reports of the non-removal
of a symlink due to the incorrect declaration of the nid
variable in unregister_mem_sect_under_nodes() because
  - systems where a memory section could have an uninitialized
    range of leading pages are probably rare.
  - memory remove is probably not done very frequently on the
    systems that are capable of demonstrating the problem.
  - lingering symlink(s) that should have been removed may
    have simply gone unnoticed.

[garyhade@us.ibm.com: wrote changelog]
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 1abaf33
Raw File
dm-bio-list.h 
/*
 * Copyright (C) 2004 Red Hat UK Ltd.
 *
 * This file is released under the GPL.
 */

#ifndef DM_BIO_LIST_H
#define DM_BIO_LIST_H

#include <linux/bio.h>

#ifdef CONFIG_BLOCK

struct bio_list {
	struct bio *head;
	struct bio *tail;
};

static inline int bio_list_empty(const struct bio_list *bl)
{
	return bl->head == NULL;
}

static inline void bio_list_init(struct bio_list *bl)
{
	bl->head = bl->tail = NULL;
}

#define bio_list_for_each(bio, bl) \
	for (bio = (bl)->head; bio; bio = bio->bi_next)

static inline unsigned bio_list_size(const struct bio_list *bl)
{
	unsigned sz = 0;
	struct bio *bio;

	bio_list_for_each(bio, bl)
		sz++;

	return sz;
}

static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
{
	bio->bi_next = NULL;

	if (bl->tail)
		bl->tail->bi_next = bio;
	else
		bl->head = bio;

	bl->tail = bio;
}

static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
{
	if (!bl2->head)
		return;

	if (bl->tail)
		bl->tail->bi_next = bl2->head;
	else
		bl->head = bl2->head;

	bl->tail = bl2->tail;
}

static inline void bio_list_merge_head(struct bio_list *bl,
				       struct bio_list *bl2)
{
	if (!bl2->head)
		return;

	if (bl->head)
		bl2->tail->bi_next = bl->head;
	else
		bl->tail = bl2->tail;

	bl->head = bl2->head;
}

static inline struct bio *bio_list_pop(struct bio_list *bl)
{
	struct bio *bio = bl->head;

	if (bio) {
		bl->head = bl->head->bi_next;
		if (!bl->head)
			bl->tail = NULL;

		bio->bi_next = NULL;
	}

	return bio;
}

static inline struct bio *bio_list_get(struct bio_list *bl)
{
	struct bio *bio = bl->head;

	bl->head = bl->tail = NULL;

	return bio;
}

#endif /* CONFIG_BLOCK */
#endif
back to top