Patch "aoe: fix crash in page count manipulation" has been added to the 4.8-stable tree

Patch "aoe: fix crash in page count manipulation" has been added to the 4.8-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    aoe: fix crash in page count manipulation

to the 4.8-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:
     aoe-fix-crash-in-page-count-manipulation.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 0cbc72a1781250f373327dd7e306e33859a42154 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@fb.com>
Date: Fri, 11 Nov 2016 18:28:50 -0700
Subject: aoe: fix crash in page count manipulation

From: Jens Axboe <axboe@fb.com>

commit 0cbc72a1781250f373327dd7e306e33859a42154 upstream.

aoeblk contains some mysterious code, that wants to elevate the bio
vec page counts while it's under IO. That is not needed, it's
fragile, and it's causing kernel oopses for some.

Reported-by: Tested-by: Don Koch <kochd@us.ibm.com>
Tested-by: Tested-by: Don Koch <kochd@us.ibm.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/block/aoe/aoecmd.c |   41 -----------------------------------------
 1 file changed, 41 deletions(-)

--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -853,45 +853,6 @@ rqbiocnt(struct request *r)
 	return n;
 }
 
-/* This can be removed if we are certain that no users of the block
- * layer will ever use zero-count pages in bios.  Otherwise we have to
- * protect against the put_page sometimes done by the network layer.
- *
- * See http://oss.sgi.com/archives/xfs/2007-01/msg00594.html for
- * discussion.
- *
- * We cannot use get_page in the workaround, because it insists on a
- * positive page count as a precondition.  So we use _refcount directly.
- */
-static void
-bio_pageinc(struct bio *bio)
-{
-	struct bio_vec bv;
-	struct page *page;
-	struct bvec_iter iter;
-
-	bio_for_each_segment(bv, bio, iter) {
-		/* Non-zero page count for non-head members of
-		 * compound pages is no longer allowed by the kernel.
-		 */
-		page = compound_head(bv.bv_page);
-		page_ref_inc(page);
-	}
-}
-
-static void
-bio_pagedec(struct bio *bio)
-{
-	struct page *page;
-	struct bio_vec bv;
-	struct bvec_iter iter;
-
-	bio_for_each_segment(bv, bio, iter) {
-		page = compound_head(bv.bv_page);
-		page_ref_dec(page);
-	}
-}
-
 static void
 bufinit(struct buf *buf, struct request *rq, struct bio *bio)
 {
@@ -899,7 +860,6 @@ bufinit(struct buf *buf, struct request
 	buf->rq = rq;
 	buf->bio = bio;
 	buf->iter = bio->bi_iter;
-	bio_pageinc(bio);
 }
 
 static struct buf *
@@ -1127,7 +1087,6 @@ aoe_end_buf(struct aoedev *d, struct buf
 	if (buf == d->ip.buf)
 		d->ip.buf = NULL;
 	rq = buf->rq;
-	bio_pagedec(buf->bio);
 	mempool_free(buf, d->bufpool);
 	n = (unsigned long) rq->special;
 	rq->special = (void *) --n;


Patches currently in stable-queue which might be from axboe@fb.com are

queue-4.8/aoe-fix-crash-in-page-count-manipulation.patch