On Sat, Feb 25, 2017 at 01:06:22AM +0800, Coly Li wrote: > On 2017/2/24 上午7:14, NeilBrown wrote: > > On Thu, Feb 23 2017, Coly Li wrote: > > > >> > >> I tried to set up a 4 layer stacked md raid1, and reduce I/O > >> barrier bucket size to 8MB, running for 10 hours, there is no > >> deadlock observed, > > > > Try setting BARRIER_BUCKETS_NR to '1' and BARRIER_UNIT_SECTOR_BITS > > to 3 and make sure the write requests are larger than 1 page (and > > have resync happen at the same time as writes). > > Hi Neil, > > Yes, the above method triggers deadlock easily. After come to > understand how bios are handled in stacked raid1 and the relationship > between current->bio_list, plug->pending and conf->pending_bio_list, I > think I come to understand what you worried and the meaning of your fix. > > I totally agree and understand there will be hash conflict sooner or > later now. Yes we need this fix. > > Thanks to you and Shaohua, explaining the details to me, and help me > to catch up your mind :-) I'm confused. So the deadlock is real? How is it triggered? 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
