| From | Greg Kroah-Hartman <> | Subject | [ 164/171] libceph: only kunmap kmapped pages | Date | Wed, 21 Nov 2012 16:41:50 -0800 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Alex Elder <elder@inktank.com>
(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 <bryan@virginia.edu> Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Sage Weil <sage@inktank.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ceph/messenger.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
--- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -1069,16 +1069,13 @@ static int write_partial_msg_pages(struc 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;
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