On Sun, Nov 27, 2016 at 07:32:32PM +0300, Konstantin Khlebnikov wrote: > Current implementation employ 16bit counter of active stripes in lower > bits of bio->bi_phys_segments. If request is big enough to overflow > this counter bio will be completed and freed too early. > > Fortunately this not happens in default configuration because several > other limits prevent that: stripe_cache_size * nr_disks effectively > limits count of active stripes. And small max_sectors_kb at lower > disks prevent that during normal read/write operations. > > Overflow easily happens in discard if it's enabled by module parameter > "devices_handle_discard_safely" and stripe_cache_size is set big enough. > > This patch limits requests size with 256Mb - 8Kb to prevent overflows. > > Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> > Cc: Shaohua Li <shli@xxxxxxxxxx> > Cc: Neil Brown <neilb@xxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > --- > drivers/md/raid5.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c > index 92ac251e91e6..cce6057b9aca 100644 > --- a/drivers/md/raid5.c > +++ b/drivers/md/raid5.c > @@ -6984,6 +6984,15 @@ static int raid5_run(struct mddev *mddev) > stripe = (stripe | (stripe-1)) + 1; > mddev->queue->limits.discard_alignment = stripe; > mddev->queue->limits.discard_granularity = stripe; > + > + /* > + * We use 16-bit counter of active stripes in bi_phys_segments > + * (minus one for over-loaded initialization) > + */ > + blk_queue_max_hw_sectors(mddev->queue, 0xfffe * STRIPE_SECTORS); > + blk_queue_max_discard_sectors(mddev->queue, > + 0xfffe * STRIPE_SECTORS); > + > /* > * unaligned part of discard request will be ignored, so can't > * guarantee discard_zeroes_data Thanks! I applied this one, which is easy for stable too. After Neil's patches to remove the limitation, we can remove this one. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
