[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path
Thank you Juergen for your comments. I will soon send v2 patch. -Thanks, Manjunath On 10/30/2018 12:04 AM, Juergen Gross wrote: 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.patil@xxxxxxxxxx>Can you please add a "Fixes:" tag and "Cc: stable@xxxxxxxxxxxxxxx" ?--- 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@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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