On Thu, Jan 31, 2008 at 02:05:58PM +0100, Jens Axboe wrote: > On Thu, Jan 31 2008, Nai Xia wrote: > > My dmesg relevant info is quite similar: > > > > [ 6.875041] Freeing unused kernel memory: 320k freed > > [ 8.143120] ide-cd: rq still having bio: dev hdc: type=2, flags=114c8 > > [ 8.144439] > > [ 8.144439] sector 10824201199534213, nr/cnr 0/0 > > [ 8.144439] bio cf029280, biotail cf029280, buffer 00000000, data > > 00000000, len 158 > > [ 8.144439] cdb: 12 00 00 00 fe 00 00 00 00 00 00 00 00 00 00 00 > > [ 8.144439] backup: data_len=158 bi_size=158 > > [ 8.160756] ide-cd: rq still having bio: dev hdc: type=2, flags=114c8 > > [ 8.160756] > > [ 8.160756] sector 2669858, nr/cnr 0/0 > > [ 8.160756] bio cf029300, biotail cf029300, buffer 00000000, data > > 00000000, len 158 > > [ 8.160756] cdb: 12 01 00 00 fe 00 00 00 00 00 00 00 00 00 00 00 > > [ 8.160756] backup: data_len=158 bi_size=158 > > [ 14.851101] eth0: link up > > [ 27.121883] eth0: no IPv6 routers present > > > > > > And by the way, Kiyoshi, > > This can be reproduced in a typical setup vmware workstation 6.02 with > > a vritual IDE cdrom, > > in case you wanna catch that with your own eyes. :-) > > Thanks for your trying hard to correct this annoying bug. > > The below fix should be enough. It's perfectly legal to have leftover > byte counts when the drive signals completion, happens all the time for > eg user issued commands where you don't know an exact byte count. Actually, this behavior has been the case even before the __blk_end_request() changes. I did test plain 2.6.24 with the following --- linux-2.6/drivers/ide/ide-cd.c 2008-01-31 22:18:59.000000000 +0100 +++ linux-2.6/drivers/ide/ide-cd.c-new 2008-01-31 22:18:50.000000000 +0100 @@ -1711,8 +1711,12 @@ static ide_startstop_t cdrom_newpc_intr( /* * If DRQ is clear, the command has completed. */ - if ((stat & DRQ_STAT) == 0) + if ((stat & DRQ_STAT) == 0) { + blk_dump_rq_flags(rq, "ide-cd: rq still having bio"); + printk("backup: data_len=%u bi_size=%u\n", + rq->data_len, rq->bio->bi_size); goto end_request; + } /* * check which way to transfer data to see whether we've been getting residual byte counts: Jan 31 22:10:06 gollum kernel: [ 26.702877] ide-cd: rq still having bio: dev hdc: type=2, flags=114c8 Jan 31 22:10:06 gollum kernel: [ 26.702945] Jan 31 22:10:06 gollum kernel: [ 26.702946] sector 2673511, nr/cnr 0/0 Jan 31 22:10:06 gollum kernel: [ 26.703052] bio dfa8ec40, biotail dfa8ec40, buffer 00000000, data 00000000, len 158 Jan 31 22:10:06 gollum kernel: [ 26.703122] cdb: 12 00 00 00 fe 00 00 00 00 00 00 00 00 00 00 00 Jan 31 22:10:06 gollum kernel: [ 26.703877] backup: data_len=158 bi_size=158 ... so we've been simply silently ignoring this until now so i guess we don't need to BUG() for something that's totally benign. -- Regards/Gruß, Boris. - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html