This is a note to let you know that I've just added the patch titled libceph: don't bail early from try_read() when skipping a message to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: libceph-don-t-bail-early-from-try_read-when-skipping-a-message.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From e7a88e82fe380459b864e05b372638aeacb0f52d Mon Sep 17 00:00:00 2001 From: Ilya Dryomov <idryomov@xxxxxxxxx> Date: Wed, 17 Feb 2016 20:04:08 +0100 Subject: libceph: don't bail early from try_read() when skipping a message From: Ilya Dryomov <idryomov@xxxxxxxxx> commit e7a88e82fe380459b864e05b372638aeacb0f52d upstream. The contract between try_read() and try_write() is that when called each processes as much data as possible. When instructed by osd_client to skip a message, try_read() is violating this contract by returning after receiving and discarding a single message instead of checking for more. try_write() then gets a chance to write out more requests, generating more replies/skips for try_read() to handle, forcing the messenger into a starvation loop. Reported-by: Varada Kari <Varada.Kari@xxxxxxxxxxx> Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx> Tested-by: Varada Kari <Varada.Kari@xxxxxxxxxxx> Reviewed-by: Alex Elder <elder@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ceph/messenger.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -2340,7 +2340,7 @@ static int read_partial_message(struct c con->in_base_pos = -front_len - middle_len - data_len - sizeof(m->footer); con->in_tag = CEPH_MSGR_TAG_READY; - return 0; + return 1; } else if ((s64)seq - (s64)con->in_seq > 1) { pr_err("read_partial_message bad seq %lld expected %lld\n", seq, con->in_seq + 1); @@ -2366,7 +2366,7 @@ static int read_partial_message(struct c sizeof(m->footer); con->in_tag = CEPH_MSGR_TAG_READY; con->in_seq++; - return 0; + return 1; } BUG_ON(!con->in_msg); Patches currently in stable-queue which might be from idryomov@xxxxxxxxx are queue-4.4/libceph-fix-ceph_msg_revoke.patch queue-4.4/tcp-dccp-fix-another-race-at-listener-dismantle.patch queue-4.4/libceph-don-t-spam-dmesg-with-stray-reply-warnings.patch queue-4.4/libceph-don-t-bail-early-from-try_read-when-skipping-a-message.patch queue-4.4/libceph-use-the-right-footer-size-when-skipping-a-message.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html