From: Shriram Rajagopalan <rshriram@gmail.com>
To: Kaushik Kumar Ram <kaushik@rice.edu>
Cc: xen-devel@lists.xensource.com
Subject: Re: blktap2 and CONFIG_XEN_BLKBACK_PAGEMAP
Date: Thu, 15 Jul 2010 11:19:26 -0700 [thread overview]
Message-ID: <AANLkTikrRhnrQd3dA4l0C8l-sTrYGAkS3sKA9LzmEHCs@mail.gmail.com> (raw)
In-Reply-To: <2E49F371-C04A-4DE2-9945-66ABADD0042C@rice.edu>
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IIRC during my early experiments with blkback & blktap2, I hit a similar
error.. tracing through the code, I gathered that the pagemap stuff is used
to manage page grants to blktap2 kernel driver . So, the #else (ie
!BLKBK_PAGEMAP) code is not going to work.
I suggest, you try to look at the blkback_pagemap.c and the blktap2/device.c
or something like that to get a better picture.
On Wed, Jul 14, 2010 at 4:59 PM, Kaushik Kumar Ram <kaushik@rice.edu> wrote:
> Is it necessary to use blkback_pagemap with blktap2? Since the use of
> blkback_pagemap is configurable I tried without it and my system crashed
> (crash dump attached below). Or is it a bug?
>
> I am using about a month old xen-unstable.hg with linux-2.6.18-xen.hg (both
> 64 bit).
>
> Thanks.
> -Kaushik
>
> (XEN) mm.c:889:d0 Error getting mfn 80765 (pfn 3fba6) from L1 entry
> 8000000080765027 for l1e_owner=0, pg_owner=0
> (XEN) mm.c:5046:d0 ptwr_emulate: could not get_page_from_l1e()
> Unable to handle kernel paging request at ffff8800388f6688 RIP:
> [<ffffffff803dc7d6>] blktap_map_uaddr_fn+0xa6/0xc0
> PGD 1140067 PUD 1141067 PMD 1306067 PTE 80100000388f6065
> Oops: 0003 [1] SMP
> CPU 0
> Modules linked in: e1000e sd_mod ata_piix libata thermal fan
> Pid: 4183, comm: blkback.1.sda1 Not tainted 2.6.18.8-xen0 #40
> RIP: e030:[<ffffffff803dc7d6>] [<ffffffff803dc7d6>]
> blktap_map_uaddr_fn+0xa6/0xc0
> RSP: e02b:ffff880039d01840 EFLAGS: 00010297
> RAX: 8000000080765027 RBX: ffff8800388f6688 RCX: ffff880039d01908
> RDX: 00002b218a8d1000 RSI: ffff880001fb15d0 RDI: ffff8800388f6688
> RBP: ffff880039d01850 R08: 00000000000388f6 R09: 0000000000000000
> R10: 0000000000000000 R11: 00000000000002c8 R12: ffff8800388f6688
> R13: 00002b218a8d1000 R14: 00002b218a8d2000 R15: ffff88003890e2a0
> FS: 00002af9674c06e0(0000) GS:ffffffff8058c000(0000)
> knlGS:0000000000000000
> CS: e033 DS: 0000 ES: 0000
> Process blkback.1.sda1 (pid: 4183, threadinfo ffff880039d00000, task
> ffff88003e8cf080)
> Stack: ffff8800388f6688 ffff880001fb15d0 ffff880039d018f0 ffffffff80270033
> 0000001a00000039 ffff880039d01908 ffffffff803dc730 ffff88003a714080
> ffff8800389802b0 00002b218a8d2000 00002b218a8d2000 ffff88003c03b430
> Call Trace:
> [<ffffffff80270033>] apply_to_page_range+0x4e3/0x590
> [<ffffffff803dc730>] blktap_map_uaddr_fn+0x0/0xc0
> [<ffffffff803dac01>] blktap_map_uaddr+0x21/0x30
> [<ffffffff803db70c>] blktap_device_do_request+0x67c/0xfe0
> [<ffffffff8023f36c>] __mod_timer+0xbc/0xe0
> [<ffffffff802088b0>] __switch_to+0x370/0x5b0
> [<ffffffff8023f1dc>] lock_timer_base+0x2c/0x60
> [<ffffffff8023f9c6>] del_timer+0x56/0x70
> [<ffffffff80344715>] __generic_unplug_device+0x25/0x30
> [<ffffffff803459d0>] generic_unplug_device+0x20/0x60
> [<ffffffff803d3196>] unplug_queue+0x26/0x50
> [<ffffffff803d3dea>] blkif_schedule+0x55a/0x690
> [<ffffffff803d3890>] blkif_schedule+0x0/0x690
> [<ffffffff8024b12a>] kthread+0xda/0x110
> [<ffffffff8020a428>] child_rip+0xa/0x12
> [<ffffffff8024b050>] kthread+0x0/0x110
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>
--
perception is but an offspring of its own self
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next prev parent reply other threads:[~2010-07-15 18:19 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-14 23:59 blktap2 and CONFIG_XEN_BLKBACK_PAGEMAP Kaushik Kumar Ram
2010-07-15 18:19 ` Shriram Rajagopalan [this message]
2010-07-15 19:02 ` Kaushik Kumar Ram
2010-07-15 22:06 ` Shriram Rajagopalan
2010-07-16 20:16 ` Daniel Stodden
2010-07-17 0:53 ` Jeremy Fitzhardinge
2010-07-17 0:56 ` Daniel Stodden
2010-07-19 13:36 ` Ian Campbell
2010-07-19 16:53 ` Daniel Stodden
2010-07-19 17:27 ` Jake Wires
2010-08-06 12:33 ` Jan Beulich
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