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[Xen-devel] Module Error

To: Xen-devel@xxxxxxxxxxxxxxxxxxx, xen-users <Xen-users@xxxxxxxxxxxxxxxxxxx>

From: Artur Baruchi <mail.baruchi@xxxxxxxxx>

Date: Sun, 30 Oct 2011 19:16:11 -0200

Cc:

Delivery-date: Mon, 14 Nov 2011 15:17:26 -0800

List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Hi. Im writing a kernel module to extract some information from kernel, the module is working really fine in an AMD (AMD Athlon(tm) 64 X2 Dual Core Processor 3800+), but, when trying to run the module in a i7 (Intel(R) Core(TM) i7 CPU 930 @ 2.80GHz) Im facing some strange errors (see below). The kernel versions are just the same on both machines (2.6.34.10-0.2-xen #1 SMP x86_64 x86_64 x86_64 GNU/Linux). The difference are the amount of memory AND processor vendor. I noted that the line of code that hangs my machine is this one: if(end->host==NULL) { The end->host points to an Inode type (end is an address_space type). If I remove this line, the module works (but, obviously, do not return what I want). I tried the same code in a kernel without xen (2.6.34.10-0.2-desktop #1 SMP x86_64 x86_64 x86_64 GNU/Linux) and worked fine, so I suppose that this error is due to something in Xen running in a intel processor (I tried the module in an intel quad, and got the same error). Follow some outputs: The error stack: Oct 28 23:40:35 goku kernel: [ 4472.129718] BUG: unable to handle kernel paging request at 000003d600000004 Oct 28 23:40:35 goku kernel: [ 4472.129933] IP: [<ffffffffa08d118c>] get_files+0x6c/0x220 [pagecache] Oct 28 23:40:35 goku kernel: [ 4472.130098] PGD 0 Oct 28 23:40:35 goku kernel: [ 4472.130250] Oops: 0000 [#4] SMP Oct 28 23:40:35 goku kernel: [ 4472.130452] last sysfs file: /sys/devices/system/cpu/cpu7/online Oct 28 23:40:35 goku kernel: [ 4472.130562] CPU 0 Oct 28 23:40:35 goku kernel: [ 4472.130615] Modules linked in: pagecache ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager ocfs2_stackglue configfs drbd crc32c libcrc32c bridge stp llc nfsd lockd nfs_acl snd_pcm_oss auth_rpcgss snd_mixer_oss usbbk gntdev netbk blkbk blkback_pagemap blktap domctl xenbus_be snd_seq evtchn snd_seq_device sunrpc exportfs edd fuse loop snd_hda_codec_realtek firewire_ohci snd_hda_intel firewire_core snd_hda_codec crc_itu_t snd_hwdep snd_pcm snd_timer ohci1394 iTCO_wdt snd soundcore sr_mod xhci_hcd ieee1394 i2c_i801 iTCO_vendor_support pcspkr snd_page_alloc sg r8169 wmi serio_raw ext4 jbd2 crc16 linear uhci_hcd sd_mod nouveau ehci_hcd ttm drm_kms_helper usbcore drm agpgart i2c_algo_bit i2c_core button dm_snapshot dm_mod xenblk cdrom xennet fan processor ata_piix ahci pata_jmicron ata_generic libata scsi_mod thermal thermal_sys hwmon Oct 28 23:40:35 goku kernel: [ 4472.132037] Oct 28 23:40:35 goku kernel: [ 4472.132037] Pid: 4641, comm: cat Tainted: G D 2.6.34.10-0.2-xen #1 X58A-UD3R/X58A-UD3R Oct 28 23:40:35 goku kernel: [ 4472.132037] RIP: e030:[<ffffffffa08d118c>] [<ffffffffa08d118c>] get_files+0x6c/0x220 [pagecache] Oct 28 23:40:35 goku kernel: [ 4472.132037] RSP: e02b:ffff8801ded93c88 EFLAGS: 00010246 Oct 28 23:40:35 goku kernel: [ 4472.132037] RAX: 8000000004000400 RBX: ffff8801e8ea5bd0 RCX: 0000000000000001 Oct 28 23:40:35 goku kernel: [ 4472.132037] RDX: ffff8801efc8c7e8 RSI: ffffffffa08d15c0 RDI: ffff8801e8ea4c28 Oct 28 23:40:35 goku kernel: [ 4472.132037] RBP: 0000000000000001 R08: ffff8801eed81e00 R09: 0000000000000000 Oct 28 23:40:35 goku kernel: [ 4472.132037] R10: ffff8801e8ea5c00 R11: 0000000000000000 R12: 00000000001e6000 Oct 28 23:40:35 goku kernel: [ 4472.132037] R13: 0000000006a50000 R14: ffff8801e8ea5b88 R15: 000003d600000004 Oct 28 23:40:35 goku kernel: [ 4472.132037] FS: 00007fcb81c3b700(0000) GS:ffff88000200b000(0000) knlGS:0000000000000000 Oct 28 23:40:35 goku kernel: [ 4472.132037] CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 Oct 28 23:40:35 goku kernel: [ 4472.132037] CR2: 000003d600000004 CR3: 00000001edecf000 CR4: 0000000000002660 Oct 28 23:40:35 goku kernel: [ 4472.132037] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Oct 28 23:40:35 goku kernel: [ 4472.132037] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Oct 28 23:40:35 goku kernel: [ 4472.132037] Process cat (pid: 4641, threadinfo ffff8801ded92000, task ffff8801eedfa780) Oct 28 23:40:35 goku kernel: [ 4472.132037] Stack: Oct 28 23:40:35 goku kernel: [ 4472.132037] 0000000101baa5b4 0000000200000002 0000000000000000 ffff8801f16ffae8 Oct 28 23:40:35 goku kernel: [ 4472.132037] <0> 0000000000000000 ffff8801ee7c6500 ffff8801efd32bc0 ffff8801e45de2d0 Oct 28 23:40:35 goku kernel: [ 4472.132037] <0> ffff8801ee7c6500 ffff8801f05d80f8 ffffffff801314f0 ffffffffa08d1349 Oct 28 23:40:35 goku kernel: [ 4472.132037] Call Trace: Oct 28 23:40:35 goku kernel: [ 4472.132037] [<ffffffffa08d1349>] cache_open+0x9/0x20 [pagecache] Oct 28 23:40:35 goku kernel: [ 4472.132037] [<ffffffff8016c529>] proc_reg_open+0xb9/0x240 Oct 28 23:40:35 goku kernel: [ 4472.132037] [<ffffffff8011060b>] __dentry_open+0xeb/0x340 Oct 28 23:40:35 goku kernel: [ 4472.132037] [<ffffffff801206a8>] finish_open+0xe8/0x1c0 Oct 28 23:40:35 goku kernel: [ 4472.132037] [<ffffffff80120f40>] do_filp_open+0x1a0/0x630 Oct 28 23:40:35 goku kernel: [ 4472.132037] [<ffffffff8011214a>] do_sys_open+0x6a/0x140 Oct 28 23:40:35 goku kernel: [ 4472.132037] [<ffffffff80007438>] system_call_fastpath+0x16/0x1b Oct 28 23:40:35 goku kernel: [ 4472.132037] [<00007fcb817a7130>] 0x7fcb817a7130 Oct 28 23:40:35 goku kernel: [ 4472.132037] Code: 03 05 69 9d f9 df 4c 8b 78 18 4d 85 ff 0f 84 9c 00 00 00 41 f6 c7 01 0f 85 92 00 00 00 48 8b 00 a9 00 00 02 00 0f 85 84 00 00 00 <49> 8b 1f 48 85 db 0f 84 78 00 00 00 48 83 7b 40 00 74 71 4c 8b Oct 28 23:40:35 goku kernel: [ 4472.132037] RIP [<ffffffffa08d118c>] get_files+0x6c/0x220 [pagecache] Oct 28 23:40:35 goku kernel: [ 4472.132037] RSP <ffff8801ded93c88> Oct 28 23:40:35 goku kernel: [ 4472.132037] CR2: 000003d600000004 Oct 28 23:40:35 goku kernel: [ 4472.143966] ---[ end trace a998217447e12d1d ]--- Peace of code (simplified): int init_module () { unsigned long pfn; struct inode *ino; unsigned char * c; struct address_space *end; struct dentry *dentry; int fl; struct filepage * temp; struct filepage *pos; for (pfn = 0; pfn < num_physpages; pfn++) { struct page *page; if (!pfn_valid(pfn)) continue; page = pfn_to_page(pfn); if((page->mapping!=NULL) && (!PageAnon(page)) && (!PageSwapCache(page))) { end = page->mapping; if(end->host==NULL) { <- without this line, no hangs, but the module returns wrong data to me... printk(KERN_INFO "Cool... found an valid inode \n"); } } } return 0; } Thanks in advance. Att. Artur Baruchi _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel

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