From 5ce765a540f34d1e2005e1210f49f67fdf11e997 Mon Sep 17 00:00:00 2001 From: Alex Elder <elder@inktank.com> Date: Fri, 21 Sep 2012 17:59:58 -0500 Subject: [PATCH] libceph: only kunmap kmapped pages In write_partial_msg_pages(), pages need to be kmapped in order to perform a CRC-32c calculation on them. As an artifact of the way this code used to be structured, the kunmap() call was separated from the kmap() call and both were done conditionally. But the conditions under which the kmap() and kunmap() calls were made differed, so there was a chance a kunmap() call would be done on a page that had not been mapped. The symptom of this was tripping a BUG() in kunmap_high() when pkmap_count[nr] became 0. Reported-by: Bryan K. Wright <bryan@virginia.edu> Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Sage Weil <sage@inktank.com> --- net/ceph/messenger.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index 24c5eea8c45bb..159aa8bef9e7f 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -1073,16 +1073,13 @@ static int write_partial_msg_pages(struct ceph_connection *con) BUG_ON(kaddr == NULL); base = kaddr + con->out_msg_pos.page_pos + bio_offset; crc = crc32c(crc, base, len); + kunmap(page); msg->footer.data_crc = cpu_to_le32(crc); con->out_msg_pos.did_page_crc = true; } ret = ceph_tcp_sendpage(con->sock, page, con->out_msg_pos.page_pos + bio_offset, len, 1); - - if (do_datacrc) - kunmap(page); - if (ret <= 0) goto out; -- 2.30.2