BUG kmalloc-64 (Not tainted): Poison overwritten
Hi, Michael I just got the following kernel bug while working on Dave's net tree in a KVM guest. It looks like a bug in virtio. Let me know if you need more information. [ 69.816089] BUG kmalloc-64 (Not tainted): Poison overwritten [ 69.816089] - [ 69.816089] [ 69.816089] Disabling lock debugging due to kernel taint [ 69.816089] INFO: 0x8800d480c7c0-0x8800d480c7c0. First byte 0x6a instead of 0x6b [ 69.816089] INFO: Allocated in virtqueue_add+0x6b/0x2a2 age=423 cpu=3 pid=128 [ 69.816089] __slab_alloc+0x44b/0x4d2 [ 69.816089] __kmalloc+0xa3/0x14e [ 69.816089] virtqueue_add+0x6b/0x2a2 [ 69.816089] virtqueue_add_sgs+0x78/0x87 [ 69.816089] __virtblk_add_req+0x139/0x14b [ 69.816089] virtio_queue_rq+0x14e/0x1f0 [ 69.816089] __blk_mq_run_hw_queue+0x1ac/0x2b9 [ 69.816089] blk_mq_run_hw_queue+0x59/0xb8 [ 69.816089] blk_mq_insert_requests+0x136/0x1ab [ 69.816089] blk_mq_flush_plug_list+0xd4/0xe3 [ 69.816089] blk_flush_plug_list+0x9b/0x1b9 [ 69.816089] blk_finish_plug+0x24/0x33 [ 69.816089] generic_writepages+0x4c/0x59 [ 69.816089] do_writepages+0x21/0x2f [ 69.816089] __writeback_single_inode+0xd6/0x5ca [ 69.816089] writeback_sb_inodes+0x28c/0x458 [ 69.816089] INFO: Freed in detach_buf+0x3d/0x6e age=469 cpu=3 pid=128 [ 69.816089] __slab_free+0x35/0x283 [ 69.816089] kfree+0x153/0x1ac [ 69.816089] detach_buf+0x3d/0x6e [ 69.816089] virtqueue_get_buf+0xac/0xdd [ 69.816089] virtblk_done+0x61/0xcb [ 69.816089] vring_interrupt+0x2d/0x3c [ 69.816089] handle_irq_event_percpu+0xbd/0x2c0 [ 69.816089] handle_irq_event+0x4a/0x6e [ 69.816089] handle_edge_irq+0xc0/0xe3 [ 69.816089] handle_irq+0x11b/0x128 [ 69.816089] do_IRQ+0x4d/0xc1 [ 69.816089] ret_from_intr+0x0/0x1d [ 70.780063] kmem_cache_free+0xb2/0x248 [ 70.780063] ext4_release_io_end+0x78/0xa9 [ 70.780063] ext4_put_io_end+0x50/0x5f [ 70.780063] ext4_writepages+0x662/0xb62 [ 70.780063] INFO: Slab 0xea0003520300 objects=20 used=20 fp=0x (null) flags=0x1804080 [ 70.780063] INFO: Object 0x8800d480c7a8 @offset=1960 fp=0x8800d480db90 [ 70.780063] [ 70.780063] Bytes b4 8800d480c798: 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a [ 70.780063] Object 8800d480c7a8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b [ 70.780063] Object 8800d480c7b8: 6b 6b 6b 6b 6b 6b 6b 6b 6a 6b 6b 6b 6b 6b 6b 6b jkkk [ 70.780063] Object 8800d480c7c8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b [ 70.780063] Object 8800d480c7d8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkk. [ 70.780063] Redzone 8800d480c7e8: bb bb bb bb bb bb bb bb [ 70.780063] Padding 8800d480c928: 5a 5a 5a 5a 5a 5a 5a 5a [ 70.780063] CPU: 1 PID: 780 Comm: u32_del.sh Tainted: GB 4.2.0-rc7+ #1097 [ 70.780063] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 70.780063] 8800d480c7a8 8800d5a47aa8 81a64274 [ 70.780063] 88011a007700 8800d5a47ad8 81187587 8800d480c7c0 [ 70.780063] 006b 88011a007700 8800d480c7c0 8800d5a47b38 [ 70.780063] Call Trace: [ 70.780063] [81a64274] dump_stack+0x4c/0x65 [ 70.780063] [81187587] print_trailer+0x12b/0x134 [ 70.780063] [81187636] check_bytes_and_report+0xa6/0xf3 [ 70.780063] [811b8111] ? alloc_fdmem+0x2b/0x34 [ 70.780063] [81187b5a] check_object+0x111/0x1ac [ 70.780063] [811b8111] ? alloc_fdmem+0x2b/0x34 [ 70.780063] [81a5ef08] alloc_debug_processing+0x67/0x109 [ 70.780063] [81a5f3f5] __slab_alloc+0x44b/0x4d2 [ 70.780063] [811b8111] ? alloc_fdmem+0x2b/0x34 [ 70.780063] [810a34aa] ? __might_sleep+0x78/0x80 [ 70.780063] [81189388] __kmalloc+0xa3/0x14e [ 70.780063] [811b8111] ? alloc_fdmem+0x2b/0x34 [ 70.780063] [811b8111] alloc_fdmem+0x2b/0x34 [ 70.780063] [811b81ab] alloc_fdtable+0x91/0xc2 [ 70.780063] [811b8aca] dup_fd+0x15d/0x2fc [ 70.780063] [8107866a] copy_process.part.33+0x704/0x1837 [ 70.780063] [810a43b4] ? sched_clock_cpu+0x9e/0xb7 [ 70.780063] [810a44a7] ? local_clock+0x19/0x22 [ 70.780063] [810e41cb] ? current_kernel_time+0xe/0x32 [ 70.780063] [8107994f] _do_fork+0xd3/0x371 [ 70.780063] [810e41cb] ? current_kernel_time+0xe/0x32 [ 70.780063] [81106d79] ? __audit_syscall_entry+0xbf/0xe1 [ 70.780063] [8100e658] ? do_audit_syscall_entry+0x63/0x65 [ 70.780063] [8100f429] ? syscall_trace_enter_phase1+0x11a/0x125 [ 70.780063] [81079c73] SyS_clone+0x19/0x1b [ 70.780063] [81a703d7]
A question about vring operation
Hi all, I have a question about the vring_avail: It only includes an idx (equivalent to the ring tail), which is used by the frontend (virtio_net) to fill bufs. The backend (e.g. vhost_net) maintains the ring head (last_avail_idx) by itself. The frontend checks if the ring is full or empty via a counter (vq-num_free). My question is why can't we include the ring head in the vring_avail struct, so that the vq-num_free is not needed, and the backend can directly use it without maintaining its own copy? Thanks, Wei ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: BUG kmalloc-64 (Not tainted): Poison overwritten
On Tue, Aug 25, 2015 at 2:11 PM, Cong Wang cw...@twopensource.com wrote: Hi, Michael I just got the following kernel bug while working on Dave's net tree in a KVM guest. It looks like a bug in virtio. Hmm, the stack trace is misleading, it could be caused by my own networking code even though it doesn't show in dmesg. Anyway I can't reproduce it on the clean -net tree. I will let you know if it is really a bug. Thanks. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH net-next] virtio-net: avoid unnecessary sg initialzation
From: Jason Wang jasow...@redhat.com Date: Thu, 27 Aug 2015 14:53:06 +0800 Usually an skb does not have up to MAX_SKB_FRAGS frags. So no need to initialize the unuse part of sg. This patch initialize the sg based on the real number it will used: - during xmit, it could be inferred from nr_frags and can_push. - for small receive buffer, it will also be 2. Cc: Michael S. Tsirkin m...@redhat.com Signed-off-by: Jason Wang jasow...@redhat.com This looks fine, thanks Jason. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
[PATCH net-next] virtio-net: avoid unnecessary sg initialzation
Usually an skb does not have up to MAX_SKB_FRAGS frags. So no need to
initialize the unuse part of sg. This patch initialize the sg based on
the real number it will used:
- during xmit, it could be inferred from nr_frags and can_push.
- for small receive buffer, it will also be 2.
Cc: Michael S. Tsirkin m...@redhat.com
Signed-off-by: Jason Wang jasow...@redhat.com
---
drivers/net/virtio_net.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 53f5660..c006ae4 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -540,7 +540,7 @@ static int add_recvbuf_small(struct virtnet_info *vi,
struct receive_queue *rq,
skb_put(skb, GOOD_PACKET_LEN);
hdr = skb_vnet_hdr(skb);
- sg_init_table(rq-sg, MAX_SKB_FRAGS + 2);
+ sg_init_table(rq-sg, 2);
sg_set_buf(rq-sg, hdr, vi-hdr_len);
skb_to_sgvec(skb, rq-sg + 1, 0, skb-len);
@@ -893,7 +893,7 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff
*skb)
if (vi-mergeable_rx_bufs)
hdr-num_buffers = 0;
- sg_init_table(sq-sg, MAX_SKB_FRAGS + 2);
+ sg_init_table(sq-sg, skb_shinfo(skb)-nr_frags + (can_push ? 1 : 2));
if (can_push) {
__skb_push(skb, hdr_len);
num_sg = skb_to_sgvec(skb, sq-sg, 0, skb-len);
--
2.1.4
___
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Call for Papers - WorldCIST'15: 4td World Conference on Information Systems and Technologies
WorldCIST'16 - 4th World Conference on Information Systems and Technologies Recife, PE, Brazil 22th-24th of March 2016 http://www.aisti.eu/worldcist16/ --- SCOPE The WorldCist'16 - 4th World Conference on Information Systems and Technologies, to be held at Recife, PE, Brazil, 22 - 24 March 2016, is a global forum for researchers and practitioners to present and discuss the most recent innovations, trends, results, experiences and concerns in the several perspectives of Information Systems and Technologies. We are pleased to invite you to submit your papers to WorldCist'16. All submissions will be reviewed on the basis of relevance, originality, importance and clarity. THEMES Submitted papers should be related with one or more of the main themes proposed for the Conference: A) Information and Knowledge Management (IKM); B) Organizational Models and Information Systems (OMIS); C) Software and Systems Modeling (SSM); D) Software Systems, Architectures, Applications and Tools (SSAAT); E) Multimedia Systems and Applications (MSA); F) Computer Networks, Mobility and Pervasive Systems (CNMPS); G) Intelligent and Decision Support Systems (IDSS); H) Big Data Analytics and Applications (BDAA); I) Human-Computer Interaction (HCI); J) Health Informatics (HIS); K) Information Technologies in Education (ITE); L) Information Technologies in Radiocommunications (ITR). TYPES OF SUBMISSIONS AND DECISIONS Four types of papers can be submitted: - Full paper: Finished or consolidated RD works, to be included in one of the Conference themes. These papers are assigned a 10-page limit. - Short paper: Ongoing works with relevant preliminary results, open to discussion. These papers are assigned a 7-page limit. -Poster paper: Initial work with relevant ideas, open to discussion. These papers are assigned to a 4-page limit. - Company paper: Companies' papers that show practical experience, R D, tools, etc., focused on some topics of the conference. These papers are assigned to a 4-page limit. Submitted papers must comply with the format of Advances in Intelligent Systems and Computing Series (see Instructions for Authors at Springer Website or download a DOC example) be written in English, must not have been published before, not be under review for any other conference or publication and not include any information leading to the authors identification. Therefore, the authors names, affiliations and bibliographic references should not be included in the version for evaluation by the Program Committee. This information should only be included in the camera-ready version, saved in Word or Latex format and also in PDF format. These files must be accompanied by the Consent to Publication form filled out, in a ZIP file, and uploaded at the conference management system. All papers will be subjected to a double-blind review by at least two members of the Program Committee. Based on Program Committee evaluation, a paper can be rejected or accepted by the Conference Chairs. In the later case, it can be accepted as the type originally submitted or as another type. Thus, full papers can be accepted as short papers or poster papers only. Similarly, short papers can be accepted as poster papers only. In these cases, the authors will be allowed to maintain the original number of pages in the camera-ready version. The authors of accepted poster papers must also build and print a poster to be exhibited during the Conference. This poster must follow an A1 or A2 vertical format. The Conference can includes Work Sessions where these posters are presented and orally discussed, with a 5 minute limit per poster. The authors of accepted full papers will have 15 minutes to present their work in a Conference Work Session; approximately 5 minutes of discussion will follow each presentation. The authors of accepted short papers and company papers will have 11 minutes to present their work in a Conference Work Session; approximately 4 minutes of discussion will follow each presentation. PUBLICATION AND INDEXING To ensure that a full paper, short paper, poster paper or company paper is published in the Proceedings, at least one of the authors must be fully registered by the 27th of December 2015, and the paper must comply with the suggested layout and page-limit. Additionally, all recommended changes must be addressed by the authors before they submit the camera-ready version. No more than one paper per registration will be published in the Conference Proceedings. An extra fee must be paid for publication of additional papers, with a maximum of one additional paper per registration. Full and short papers will be published in Proceedings by Springer, in a book of Advances in Intelligent Systems and Computing series. Poster and company papers will be published by AISTI. Published full and short papers will be submitted for indexation by ISI,
