From patchwork Tue Nov 20 17:19:36 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [3.5.yuz, extended, stable] Patch "libceph: only kunmap kmapped pages" has been added to staging queue Date: Tue, 20 Nov 2012 07:19:36 -0000 From: Herton Ronaldo Krzesinski X-Patchwork-Id: 200480 Message-Id: <1353431976-11215-1-git-send-email-herton.krzesinski@canonical.com> To: Alex Elder Cc: "Bryan K. Wright" , kernel-team@lists.ubuntu.com, Sage Weil This is a note to let you know that I have just added a patch titled libceph: only kunmap kmapped pages to the linux-3.5.y-queue branch of the 3.5.yuz extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.yuz tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Herton ------ >From 38c1cfbc01e54212f13710a2175289fbaa391cfa Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Fri, 21 Sep 2012 17:59:58 -0500 Subject: [PATCH 72/78] libceph: only kunmap kmapped pages commit 5ce765a540f34d1e2005e1210f49f67fdf11e997 upstream. 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: Herton Ronaldo Krzesinski --- net/ceph/messenger.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) -- 1.7.9.5 diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index b141c86..8ba0eee 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;