| Message ID | 20111112054546.9555.7764.sendpatchset@krkumar2.in.ibm.com |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
On Sat, 2011-11-12 at 11:15 +0530, Krishna Kumar wrote: > Sasha Levin <levinsasha928@gmail.com> wrote on 11/12/2011 03:32:04 AM: > > > I'm seeing this BUG() sometimes when running it using a small patch I > > did for KVM tool: > > > > [ 1.281531] Call Trace: > > [ 1.281531] [<ffffffff8138a0e5>] ? free_rq_sq+0x2c/0xce > > [ 1.281531] [<ffffffff8138bb63>] ? virtnet_probe+0x81c/0x855 > > [ 1.281531] [<ffffffff8129c9e7>] ? virtio_dev_probe+0xa7/0xc6 > > [ 1.281531] [<ffffffff8134d2c3>] ? driver_probe_device+0xb2/0x142 > > [ 1.281531] [<ffffffff8134d3a2>] ? __driver_attach+0x4f/0x6f > > [ 1.281531] [<ffffffff8134d353>] ? driver_probe_device+0x142/0x142 > > [ 1.281531] [<ffffffff8134c3ab>] ? bus_for_each_dev+0x47/0x72 > > [ 1.281531] [<ffffffff8134c90d>] ? bus_add_driver+0xa2/0x1e6 > > [ 1.281531] [<ffffffff81cc1b36>] ? tun_init+0x89/0x89 > > [ 1.281531] [<ffffffff8134db59>] ? driver_register+0x8d/0xf8 > > [ 1.281531] [<ffffffff81cc1b36>] ? tun_init+0x89/0x89 > > [ 1.281531] [<ffffffff81c98ac1>] ? do_one_initcall+0x78/0x130 > > [ 1.281531] [<ffffffff81c98c0e>] ? kernel_init+0x95/0x113 > > [ 1.281531] [<ffffffff81658274>] ? kernel_thread_helper+0x4/0x10 > > [ 1.281531] [<ffffffff81c98b79>] ? do_one_initcall+0x130/0x130 > > [ 1.281531] [<ffffffff81658270>] ? gs_change+0x13/0x13 > > [ 1.281531] Code: c2 85 d2 48 0f 45 2d d1 39 ce 00 eb 22 65 8b 14 25 > > 90 cc 00 00 48 8b 05 f0 a6 bc 00 48 63 d2 4c 89 e7 48 03 3c d0 e8 83 dd > > 00 00 > > [ 1.281531] 8b 68 10 44 89 e6 48 89 ef 2b 75 18 e8 e4 f1 ff ff 8b 05 > > fd > > [ 1.281531] RIP [<ffffffff810b3ac7>] free_percpu+0x9a/0x104 > > [ 1.281531] RSP <ffff88001383fd50> > > [ 1.281531] CR2: 0000000000000010 > > [ 1.281531] ---[ end trace 68cbc23dfe2fe62a ]--- > > > > I don't have time today to dig into it, sorry. > > Thanks for the report. > > free_rq_sq() was being called twice in the failure path. The second > call panic'd since it had freed the same pointers earlier. > > 1. free_rq_sq() was being called twice in the failure path. > virtnet_setup_vqs() had already freed up rq/sq on error, and > virtnet_probe() tried to do it again. Fix it in virtnet_probe > by moving the call up. > 2. Make free_rq_sq() re-entrant by setting freed pointers to NULL. > 3. Remove free_stats() as it was being called only once. > > Sasha, could you please try this patch on top of existing patches? > > thanks! > > Signed-off-by: krkumar2@in.ibm.com > --- [snip] I've tested it and it looks good, no BUG() or panic. I would suggest adding some output if we take the failure path, since while the guest does boot peacefully, it doesn't have a network interface and there's nothing in the boot log to indicate anything has gone wrong.
diff -ruNp n6/drivers/net/virtio_net.c n7/drivers/net/virtio_net.c --- n6/drivers/net/virtio_net.c 2011-11-12 11:03:48.000000000 +0530 +++ n7/drivers/net/virtio_net.c 2011-11-12 10:39:28.000000000 +0530 @@ -782,23 +782,6 @@ static void virtnet_netpoll(struct net_d } #endif -static void free_stats(struct virtnet_info *vi) -{ - int i; - - for (i = 0; i < vi->num_queue_pairs; i++) { - if (vi->sq && vi->sq[i]) { - free_percpu(vi->sq[i]->stats); - vi->sq[i]->stats = NULL; - } - - if (vi->rq && vi->rq[i]) { - free_percpu(vi->rq[i]->stats); - vi->rq[i]->stats = NULL; - } - } -} - static int virtnet_open(struct net_device *dev) { struct virtnet_info *vi = netdev_priv(dev); @@ -1054,19 +1037,22 @@ static void free_rq_sq(struct virtnet_in { int i; - free_stats(vi); - - if (vi->rq) { - for (i = 0; i < vi->num_queue_pairs; i++) + for (i = 0; i < vi->num_queue_pairs; i++) { + if (vi->rq && vi->rq[i]) { + free_percpu(vi->rq[i]->stats); kfree(vi->rq[i]); - kfree(vi->rq); - } + vi->rq[i] = NULL; + } - if (vi->sq) { - for (i = 0; i < vi->num_queue_pairs; i++) + if (vi->sq && vi->sq[i]) { + free_percpu(vi->sq[i]->stats); kfree(vi->sq[i]); - kfree(vi->sq); + vi->sq[i] = NULL; + } } + + kfree(vi->rq); + kfree(vi->sq); } static void free_unused_bufs(struct virtnet_info *vi) @@ -1387,10 +1373,9 @@ free_vqs: for (i = 0; i < num_queue_pairs; i++) cancel_delayed_work_sync(&vi->rq[i]->refill); vdev->config->del_vqs(vdev); - -free_netdev: free_rq_sq(vi); +free_netdev: free_netdev(dev); return err; }