On Sun, 2016-02-21 at 13:43 -0500, John David Anglin wrote: > I verified that commit 54efd50bfd873e2dbf784e0b21a8027ba4299a3e in > linux-block fails to > boot and commit 41609892701e26724b8617201f43254cadf2e7ae (blk-cgroup: > Drop unlikely > before IS_ERR(_OR_NULL)) does boot successfully. Commit > 41609892701e26724b8617201f43254cadf2e7ae > is previous commit in tree. > > I don't believe that the change can be reverted from Linus' tree as > this commit allowed other > stuff to be removed (see second paragraph of commit description). OK, can you just verify you can boot 4.5-rc5 without the sata_sil24 driver? My theory, based on what Helge produced is that this commit is building a large transfer list > 65535 and then splitting it wrongly. I think the problem is that it's not respecting the DMA boundary, so Helge sees a transfer size of 69632 which I think slops over on both sides, requiring 3 segments to describe. However, the merge code thinks we only need two (because the length is < 2*65536). The reason we only see this with ATA drivers is because virtually no SCSI drivers set the DMA boundary. Most ATA drivers require a dma boundary of 65535. James -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
