On 29/10/2018 19:31, 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"
Please us the correct format for specifying another commit. > Signed-off-by: Manjunath Patil <manjunath.b.pa...@oracle.com> Can you please add a "Fixes:" tag and "Cc: sta...@vger.kernel.org" ? > --- > 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'd drop this change. > > kfree(info->rinfo); > info->rinfo = NULL; > @@ -1919,6 +1921,7 @@ static int negotiate_mq(struct blkfront_info *info) > GFP_KERNEL); > if (!info->rinfo) { > xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info > structure"); > + info->nr_rings = 0; > return -ENOMEM; > } Juergen _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel