From 21e292e34c48c03fb6638c2d1295ca12dac97b03 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Fri, 21 Sep 2012 17:59:58 -0500 Subject: libceph: only kunmap kmapped pages (cherry picked from commit 5ce765a540f34d1e2005e1210f49f67fdf11e997) 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 Signed-off-by: Alex Elder Reviewed-by: Sage Weil Signed-off-by: Greg Kroah-Hartman --- 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 5f312510f49c..6577a9fc6ce7 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -1069,16 +1069,13 @@ 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; -- cgit v1.2.3