From: Alex Elder Date: Fri, 21 Sep 2012 22:59:58 +0000 (-0500) Subject: libceph: only kunmap kmapped pages X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=5ce765a540f34d1e2005e1210f49f67fdf11e997;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git 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 Signed-off-by: Alex Elder Reviewed-by: Sage Weil --- diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index 24c5eea8c45b..159aa8bef9e7 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;