On Tue, Dec 15, 2015 at 11:38:41PM +0800, Ming Lei wrote: > On Tue, 15 Dec 2015 21:06:31 +0800 > Eryu Guan <guaneryu@xxxxxxxxx> wrote: > > > On Tue, Dec 15, 2015 at 08:06:47PM +0800, Ming Lei wrote: > > > On Tue, Dec 15, 2015 at 7:20 PM, Eryu Guan <guaneryu@xxxxxxxxx> wrote: > > > > On Fri, Dec 11, 2015 at 07:53:40PM +0800, Eryu Guan wrote: > > > >> Hi, > > > >> > > > >> I saw this kernel BUG_ON on 4.4-rc4 kernel, and this can be reproduced > > > >> easily on ppc64 host by: > > > > > > > > This is still reproducible with 4.4-rc5 kernel. > > > > > > Could you capture the debug log after appyling the attached patch and > > > the reproduction? > > > > Thanks for looking into this! dmesg shows: > > > > [ 686.217682] bio_split: sectors 0, bio_sectors 128, bi_rw 0 > > I guess the following patch should fix the issue, and ca369d51b3 > uses OPTIMAL TRANSFER LENGTH to set limits->max_sectors, which > may be less than one page size. > > I don't understand the idea behind this change, Martin, could > you explain it a bit? > > --- > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index 3d22fc3..d66d362 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -2889,10 +2889,11 @@ static int sd_revalidate_disk(struct gendisk *disk) > */ > if (sdkp->opt_xfer_blocks && sdkp->opt_xfer_blocks <= dev_max && > sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS) > - rw_max = q->limits.io_opt = > + q->limits.io_opt = > logical_to_sectors(sdp, sdkp->opt_xfer_blocks); > - else > - rw_max = BLK_DEF_MAX_SECTORS; > + > + rw_max = min_t(unsigned, BLK_DEF_MAX_SECTORS, > + q->limits.max_dev_sectors); > > /* Combine with controller limits */ > q->limits.max_sectors = min(rw_max, queue_max_hw_sectors(q)); I tested this patch and no BUG_ON this time, the debug messages are not triggered either. Thanks, Eryu -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
