attempt to access beyond end of device

attempt to access beyond end of device

[Jan Niehusmann]

ll_rw_blk.c: generic_make_request() contains the following code:

if (maxsector < count || maxsector - count < sector) {
	bh->b_state &= (1 << BH_Lock) | (1 << BH_Mapped);
	if (blk_size[major][MINOR(bh->b_rdev)]) {

		/* This may well happen - the kernel calls bread()
		   without checking the size of the device, e.g.,
		   when mounting a device. */
		printk(KERN_INFO
		       "attempt to access beyond end of device\n");
		printk(KERN_INFO "%s: rw=%d, want=%d, limit=%d\n",
		       kdevname(bh->b_rdev), rw,
		       (sector + count)>>1,
		       blk_size[major][MINOR(bh->b_rdev)]);
	}
	bh->b_end_io(bh, 0);
	return;
}


That means that if blk_size[major][MINOR(bh->b_rdev)] == 0, the request
is canceled but no message is printed. Shouldn't there be a warning message?

Jan





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Re: attempt to access beyond end of device

[Andries Brouwer]

On Thu, Dec 07, 2000 at 04:56:59PM +0100, Jan Niehusmann wrote:
> ll_rw_blk.c: generic_make_request() contains the following code:
> 
> if (maxsector < count || maxsector - count < sector) {
> 	bh->b_state &= (1 << BH_Lock) | (1 << BH_Mapped);
> 	if (blk_size[major][MINOR(bh->b_rdev)]) {
> 
> 		/* This may well happen - the kernel calls bread()
> 		   without checking the size of the device, e.g.,
> 		   when mounting a device. */
> 		printk(KERN_INFO
> 		       "attempt to access beyond end of device\n");
> 		printk(KERN_INFO "%s: rw=%d, want=%d, limit=%d\n",
> 		       kdevname(bh->b_rdev), rw,
> 		       (sector + count)>>1,
> 		       blk_size[major][MINOR(bh->b_rdev)]);
> 	}
> 	bh->b_end_io(bh, 0);
> 	return;
> }
> 
> 
> That means that if blk_size[major][MINOR(bh->b_rdev)] == 0, the request
> is canceled but no message is printed. Shouldn't there be a warning message?

Maybe that code fragment is mine. If so, then at some point
in time I decided that the answer to your question is no.

Andries
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Re: attempt to access beyond end of device

[John Kennedy]

On Thu, Dec 07, 2000 at 05:34:28PM +0100, Andries Brouwer wrote:
> On Thu, Dec 07, 2000 at 04:56:59PM +0100, Jan Niehusmann wrote:
> > That means that if blk_size[major][MINOR(bh->b_rdev)] == 0, the request
> > is canceled but no message is printed. Shouldn't there be a warning message?
> 
> Maybe that code fragment is mine. If so, then at some point
> in time I decided that the answer to your question is no.

  As a potential real-world case (but possibly unrelated), I had an
interesting situation crop-up while I was playing with the loopback
filesystems.

  If you just use the program-tools, you end up with a situation like:

	losetup <blah> [close all] dd <blah> [close all] losetup -d [blah]

  In my case, I was making a standalone program that did it all in one
program and I messed up in the ordering of the close() and the LOOP_CLR_FD.

  I'm pretty sure that (with my small 10K test dataset) the I/O between
the loopback device and the looped file was never hitting the disk.
If I LOOP_CLR_FD before I closed, I ended up with bad data in the looped
file and kernel errors syslogged:

	kernel: attempt to access beyond end of device
	kernel: 07:00: rw=1, want=1, limit=0
	kernel: dev 07:00 blksize=0 blocknr=0 sector=0 size=1024 count=1

  I tended to get 10 of those, one for each of the 10 1K blocks in
my test dataset.

  Doing the close() then the LOOP_CLR_FD got rid of the errors.
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Re: attempt to access beyond end of device

[Justin Pryzby]

Before anyone asks, no my disk is not full:

pryzbyj@perseus:/usr/src/penguin$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/hda1             3.7G  1.1G  2.5G  31% /
/dev/hda3              19G  349M   18G   2% /home
/dev/hda4              14G  1.5G   12G  12% /usr/src

Sizes shouldn't have changed by more than 01% since I got the error.
Interesting: rerunning `updatedb --localuser=nobody 2>/dev/null` fails to
reproduce the error.

Is the error possibly the result of filesystem corruption?  I imagine that
each directory has a pointer to the disk location of each of its member
files; if that pointer were larger than the disk size, would this error
be the result?

If this is the result of filesystem corruption, it is not necessarily a
problem with ext3 or some othersuch, as I have done some *hard* shutdowns
recently (read: control-alt-backspace on a sis motherboard).

Justin

attempt to access beyond end of device

[Justin Pryzby]

2.4.20-ac1, Debian testing.

While running `updatedb --localuser=nobody 2>/dev/null`, I receive several pages of the following message:

Dec  5 13:43:25 perseus kernel: Directory sread (sector 0x18) failed
Dec  5 13:43:25 perseus kernel: attempt to access beyond end of device
Dec  5 13:43:25 perseus kernel: 02:00: rw=0, want=12, limit=4

Some of the numbers are different sometimes.  I can post my syslog if anyone is interested, but I'm not even sure if this is a kernel issue.

Disk configuration is as follows:

pryzbyj@perseus:~$ mount
/dev/hda1 on / type ext3 (rw,errors=remount-ro)
proc on /proc type proc (rw)
/dev/hda3 on /home type ext3 (rw)
/dev/hda4 on /usr/src type ext3 (rw)

Justin

attempt to access beyond end of device

[Janek]

Hi,

I have dual P III 665 with 512 MB ram and IBM ServeRAID controller.
It has been running for 40 days without problems but yesterday during
system backup it gave me the following error to syslog:

kernel: attempt to access beyond end of device
kernel: 08:03: rw=0, want=631625768, limit=7912989
kernel: dev 08:03 blksize=4096 blocknr=1768519177 sector=1263251528 size=4096 count=1

with different want numbers.
After a while thise lines changed to :

kernel: EXT2-fs error (device sd(8,3)): ext2_free_blocks: Freeing blocks not in datazone - block = 1869575229, count = 1

After backup nothing else was printed. Machine did not crash or anything.
Only MySQL server hanged...

Is this serious ? What chould I do ?

Also I'm using RedHat 6.2 with kernel 2.2.16. MySQL 3.22.32


Thanks,
Janek Hiis


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