On 10/30/2018 3:39 AM, Roger Pau Monné wrote:
On Mon, Oct 29, 2018 at 11:31:56AM -0700, Manjunath Patil wrote:info->nr_rings isn't adjusted in case of ENOMEM error from negotiate_mq(). This leads to kernel panic in error path. Typical call stack involving panic - #8 page_fault at ffffffff8175936f [exception RIP: blkif_free_ring+33] RIP: ffffffffa0149491 RSP: ffff8804f7673c08 RFLAGS: 00010292 ... #9 blkif_free at ffffffffa0149aaa [xen_blkfront] #10 talk_to_blkback at ffffffffa014c8cd [xen_blkfront] #11 blkback_changed at ffffffffa014ea8b [xen_blkfront] #12 xenbus_otherend_changed at ffffffff81424670 #13 backend_changed at ffffffff81426dc3 #14 xenwatch_thread at ffffffff81422f29 #15 kthread at ffffffff810abe6a #16 ret_from_fork at ffffffff81754078 Though either of my changes avoid the panic, I included both the changes. This issue got introduced with "7ed8ce1 xen-blkfront: move negotiate_mq to cover all cases of new VBDs" Signed-off-by: Manjunath Patil <manjunath.b.patil@xxxxxxxxxx> --- drivers/block/xen-blkfront.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 429d201..dc8fe25 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1350,8 +1350,10 @@ static void blkif_free(struct blkfront_info *info, int suspend) if (info->rq) blk_mq_stop_hw_queues(info->rq);- for (i = 0; i < info->nr_rings; i++)- blkif_free_ring(&info->rinfo[i]); + if (info->rinfo) { + for (i = 0; i < info->nr_rings; i++) + blkif_free_ring(&info->rinfo[i]); + }I don't see the point in the if case here, you already fixed it by setting the nr_rings value which I think it's the correct way of fixing it. Thanks, Roger.
Thank you Roger for your comments. I will exclude this change and send for review again. -Thanks, Manjunath
