On Wed, Jun 19, 2002 at 10:02:48AM +0100, Dave Jones wrote:
> I got a bug report about an issue with LVM in 2.5.22-dj1, which turns
> out to be caused by broken /proc/partitions in mainline.
>
> (davej@mesh:davej)$ cat /proc/partitions
> major minor #blocks name
>
> 8 0 0 sda
> 22 0 1515870810 hdc
>
> Note the huge numbers in hex are 0x5a5a5a5a, so something
> seems to be getting poisoned somewhere.
Is this LVM?
I don't see how LVM could produce such values.
(And in fact LVM does not even compile, so only a patched LVM
could produce anything at all.)
From: Wayne Whitney <whitney@adsl-209-76-109-63.dsl.snfc21.pacbell.net>
I traced the change to the part of mainline ChangeSet 1.496 given
below (warning: cut and pasted). It seems to cause every possible
device that a driver could provide to show up in /proc/partitions.
For LVM, that's a zillion devices, and /proc/partitions overflows,
showing some random pages from memory. Reverting the patch below
makes /proc/partitions and LVM happy again.
--- a/drivers/block/genhd.c Wed May 8 09:53:06 2002
+++ b/drivers/block/genhd.c Sun Jun 9 18:58:36 2002
@@ -177,9 +177,10 @@
if (sgp == gendisk_head)
seq_puts(part, "major minor #blocks name\n\n");
- /* show all non-0 size partitions of this disk */
+ /* show the full disk and all non-0 size partitions of it */
for (n = 0; n < (sgp->nr_real << sgp->minor_shift); n++) {
- if (sgp->part[n].nr_sects == 0)
+ int minormask = (1<<sgp->minor_shift) - 1;
+ if ((n & minormask) && sgp->part[n].nr_sects == 0)
continue;
seq_printf(part, "%4d %4d %10d %s\n",
sgp->major, n, sgp->sizes[n],
Yes.
Normally the nr_real field indicates how many devices are
present. But LVM sets that to 256 even when nothing is present.
So, indeed, when all size fields are set to 0 this would probably
yield a list of 256 absent LVM devices.
Maybe LVM has to be fixed, or this patch fragment reverted, or both.
Something else is that if /proc/partitions overflows that must be
fixed independently of zeros or LVM.
Andries
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Sun Jun 23 2002 - 22:00:23 EST