I haven't really tested but I was aware of the commit before I send my last email. It doesn't seem relevant to be honest, because it doesn't change the fact that the inner loop wil only end if the whole request has been looped over. So still one big bio. There are a few things that seem suspicious to me. First of all, the inner loop has an if-break at its end that seem to practically do nothing, especially in terms of making the inner loop end when the bio reach its expected size (BIO_MAX_PAGES?). bi_size = bio_add_page(bio, ZERO_PAGE(0), sz, 0); If you take a look at bio_add_page(): https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/block/bio.c?h=v4.13-rc4#n820 it will basically always return "len", which is "sz" here, unchanged. if (bi_size < sz) break; So this pretty much never happens, with two exceptions: if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED))) return 0; which is most likely irrelevant in this case, if (bio->bi_vcnt >= bio->bi_max_vecs) return 0; which seem to matter in this case. However: if (page == bv->bv_page && offset == bv->bv_offset + bv->bv_len) { bv->bv_len += len; goto done; } ... if (bio->bi_vcnt >= bio->bi_max_vecs) return 0; ... bio->bi_vcnt++; done: bio->bi_iter.bi_size += len; return len; So if the first condition in the above quote is matched, the exception would never happen either. On 9 August 2017 at 21:38, hch@xxxxxx <hch@xxxxxx> wrote: > Does commit 615d22a51c04856efe62af6e1d5b450aaf5cc2c0 > "block: Fix __blkdev_issue_zeroout loop" fix the issue for you?
