On Wed, Oct 20 2004, Mark Rustad wrote:
> Folks,
>
> I have been having trouble with kernel crashes resulting from RAID1
> component device failures. I have been testing the robustness of an
> embedded system and have been using a drive that is known to fail after
> a time under load. When this device returns a media error, I always
> wind up with either a kernel hang or reboot. In this environment, each
> drive has four partitions, each of which is part of a RAID1 with its
> partner on the other device. Swap is on md2 so even it should be
> robust.
>
> I have gotten this result with the SuSE standard i386 smp kernels
> 2.6.5-7.97 and 2.6.5-7.108. I also get these failures with the
> kernel.org kernels 2.6.8.1, 2.6.9-rc4 and 2.6.9.
>
> The hardware setup is a two cpu Nacona with an Adaptec 7902 SCSI
> controller with two Seagate drives on a SAF-TE bus. I run three or four
> dd commands copying /dev/md0 to /dev/null to provide the activity that
> stimulates the failure.
>
> I suspect that something is going wrong in the retry of the failed I/O
> operations, but I'm really not familiar with any of this area of the
> kernel at all.
>
> In one failure, I get the following messages from kernel 2.6.9:
>
> raid1: Disk failure on sdb1, disabling device.
> raid1: sdb1: rescheduling sector 176
> raid1: sda1: redirecting sector 176 to another mirror
> raid1: sdb1: rescheduling sector 184
> raid1: sda1: redirecting sector 184 to another mirror
> Incorrect number of segments after building list
> counted 2, received 1
> req nr_sec 0, cur_nr_sec 7
This should be fixed by this patch, can you test it?
===== drivers/block/ll_rw_blk.c 1.273 vs edited =====
--- 1.273/drivers/block/ll_rw_blk.c 2004-10-19 11:40:18 +02:00
+++ edited/drivers/block/ll_rw_blk.c 2004-10-20 17:06:12 +02:00
@@ -2766,22 +2767,36 @@
{
struct bio *bio, *prevbio = NULL;
int nr_phys_segs, nr_hw_segs;
+ unsigned int phys_size, hw_size;
+ request_queue_t *q = rq->q;
if (!rq->bio)
return;
- nr_phys_segs = nr_hw_segs = 0;
+ phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
rq_for_each_bio(bio, rq) {
/* Force bio hw/phys segs to be recalculated. */
bio->bi_flags &= ~(1 << BIO_SEG_VALID);
- nr_phys_segs += bio_phys_segments(rq->q, bio);
- nr_hw_segs += bio_hw_segments(rq->q, bio);
+ nr_phys_segs += bio_phys_segments(q, bio);
+ nr_hw_segs += bio_hw_segments(q, bio);
if (prevbio) {
- if (blk_phys_contig_segment(rq->q, prevbio, bio))
+ int pseg = phys_size + prevbio->bi_size + bio->bi_size;
+ int hseg = hw_size + prevbio->bi_size + bio->bi_size;
+
+ if (blk_phys_contig_segment(q, prevbio, bio) &&
+ pseg <= q->max_segment_size) {
nr_phys_segs--;
- if (blk_hw_contig_segment(rq->q, prevbio, bio))
+ phys_size += prevbio->bi_size + bio->bi_size;
+ } else
+ phys_size = 0;
+
+ if (blk_hw_contig_segment(q, prevbio, bio) &&
+ hseg <= q->max_segment_size) {
nr_hw_segs--;
+ hw_size += prevbio->bi_size + bio->bi_size;
+ } else
+ hw_size = 0;
}
prevbio = bio;
}
--
Jens Axboe
-
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