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SubjectRe: 2.6.21-mm2 boot failure, raid autodetect, bd_set_size+0xb/0x80
On Fri, 11 May 2007 20:03:34 +0200
thunder7@xs4all.nl wrote:

> From: Andrew Morton <akpm@linux-foundation.org>
> Date: Wed, May 09, 2007 at 01:23:22AM -0700
> >
> > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.21/2.6.21-mm2/
> >
> >
> It won't boot here.
>
> AMD64 platform, raid6 partition.
>
> 2.6.21-rc7-mm2 runs fine, it's dmesg says:
>
> md: created md4
> md: bind<hda9>
> md: bind<hdc9>
> md: running: <hdc9><hda9>
> raid1: raid set md4 active with 2 out of 2 mirrors
> md4: bitmap initialized from disk: read 10/10 pages, set 46 bits, status: 0
> created bitmap (156 pages) for device md4
> md: considering hdc8 ...
> md: adding hdc8 ...
> <snip>
>
>
> where 2.6.21-mm2 halts with
>
> md: created md4
> md: bind<hda9>
> md: bind<hdc9>
> md: running: <hdc9><hda9>
> raid1: raid set md4 active with 2 out of 2 mirrors
> md4: bitmap initialized from disk: read 10/10 pages, set 46 bits, status: 0
> created bitmap (156 pages) for device md4
> Unable to handle kernel null pointer dereference
>
> bd_set_size+0xb/0x80

Yes, Neil had a whoops and a dud patch spent a day in mainline.

Hopefully the below revert (from mainline) will fix it.


From: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
To: git-commits-head@vger.kernel.org
Subject: Revert "md: improve partition detection in md array"
Date: Thu, 10 May 2007 01:59:03 GMT
Sender: git-commits-head-owner@vger.kernel.org

Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=44ce6294d07555c3d313757105fd44b78208407f
Commit: 44ce6294d07555c3d313757105fd44b78208407f
Parent: 497f050c42e46a4b1f6a9bcd8827fa5d97fe1feb
Author: Linus Torvalds <torvalds@woody.linux-foundation.org>
AuthorDate: Wed May 9 18:51:36 2007 -0700
Committer: Linus Torvalds <torvalds@woody.linux-foundation.org>
CommitDate: Wed May 9 18:51:36 2007 -0700

Revert "md: improve partition detection in md array"

This reverts commit 5b479c91da90eef605f851508744bfe8269591a0.

Quoth Neil Brown:

"It causes an oops when auto-detecting raid arrays, and it doesn't
seem easy to fix.

The array may not be 'open' when do_md_run is called, so
bdev->bd_disk might be NULL, so bd_set_size can oops.

This whole approach of opening an md device before it has been
assembled just seems to get more and more painful. I think I'm going
to have to come up with something clever to provide both backward
comparability with usage expectation, and sane integration into the
rest of the kernel."

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
drivers/md/md.c | 26 ++++++++++++++++++--------
drivers/md/raid1.c | 1 +
drivers/md/raid5.c | 2 ++
include/linux/raid/md_k.h | 1 +
4 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2901d0c..65814b0 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3104,7 +3104,6 @@ static int do_md_run(mddev_t * mddev)
struct gendisk *disk;
struct mdk_personality *pers;
char b[BDEVNAME_SIZE];
- struct block_device *bdev;

if (list_empty(&mddev->disks))
/* cannot run an array with no devices.. */
@@ -3332,13 +3331,7 @@ static int do_md_run(mddev_t * mddev)
md_wakeup_thread(mddev->thread);
md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */

- bdev = bdget_disk(mddev->gendisk, 0);
- if (bdev) {
- bd_set_size(bdev, mddev->array_size << 1);
- blkdev_ioctl(bdev->bd_inode, NULL, BLKRRPART, 0);
- bdput(bdev);
- }
-
+ mddev->changed = 1;
md_new_event(mddev);
kobject_uevent(&mddev->gendisk->kobj, KOBJ_CHANGE);
return 0;
@@ -3460,6 +3453,7 @@ static int do_md_stop(mddev_t * mddev, int mode)
mddev->pers = NULL;

set_capacity(disk, 0);
+ mddev->changed = 1;

if (mddev->ro)
mddev->ro = 0;
@@ -4599,6 +4593,20 @@ static int md_release(struct inode *inode, struct file * file)
return 0;
}

+static int md_media_changed(struct gendisk *disk)
+{
+ mddev_t *mddev = disk->private_data;
+
+ return mddev->changed;
+}
+
+static int md_revalidate(struct gendisk *disk)
+{
+ mddev_t *mddev = disk->private_data;
+
+ mddev->changed = 0;
+ return 0;
+}
static struct block_device_operations md_fops =
{
.owner = THIS_MODULE,
@@ -4606,6 +4614,8 @@ static struct block_device_operations md_fops =
.release = md_release,
.ioctl = md_ioctl,
.getgeo = md_getgeo,
+ .media_changed = md_media_changed,
+ .revalidate_disk= md_revalidate,
};

static int md_thread(void * arg)
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 1b7130c..97ee870 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2063,6 +2063,7 @@ static int raid1_resize(mddev_t *mddev, sector_t sectors)
*/
mddev->array_size = sectors>>1;
set_capacity(mddev->gendisk, mddev->array_size << 1);
+ mddev->changed = 1;
if (mddev->array_size > mddev->size && mddev->recovery_cp == MaxSector) {
mddev->recovery_cp = mddev->size << 1;
set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a72e70a..061375e 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3864,6 +3864,7 @@ static int raid5_resize(mddev_t *mddev, sector_t sectors)
sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
mddev->array_size = (sectors * (mddev->raid_disks-conf->max_degraded))>>1;
set_capacity(mddev->gendisk, mddev->array_size << 1);
+ mddev->changed = 1;
if (sectors/2 > mddev->size && mddev->recovery_cp == MaxSector) {
mddev->recovery_cp = mddev->size << 1;
set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
@@ -3998,6 +3999,7 @@ static void end_reshape(raid5_conf_t *conf)
conf->mddev->array_size = conf->mddev->size *
(conf->raid_disks - conf->max_degraded);
set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
+ conf->mddev->changed = 1;

bdev = bdget_disk(conf->mddev->gendisk, 0);
if (bdev) {
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index a121f36..de72c49 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -201,6 +201,7 @@ struct mddev_s
struct mutex reconfig_mutex;
atomic_t active;

+ int changed; /* true if we might need to reread partition info */
int degraded; /* whether md should consider
* adding a spare
*/
-
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