From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shriram Rajagopalan Subject: Re: blktap2 and CONFIG_XEN_BLKBACK_PAGEMAP Date: Thu, 15 Jul 2010 11:19:26 -0700 Message-ID: References: <2E49F371-C04A-4DE2-9945-66ABADD0042C@rice.edu> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0799845323==" Return-path: In-Reply-To: <2E49F371-C04A-4DE2-9945-66ABADD0042C@rice.edu> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Kaushik Kumar Ram Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org --===============0799845323== Content-Type: multipart/alternative; boundary=000e0cd32ede778e2d048b7124da --000e0cd32ede778e2d048b7124da Content-Type: text/plain; charset=ISO-8859-1 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 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: > [] 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:[] [] > 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: > [] apply_to_page_range+0x4e3/0x590 > [] blktap_map_uaddr_fn+0x0/0xc0 > [] blktap_map_uaddr+0x21/0x30 > [] blktap_device_do_request+0x67c/0xfe0 > [] __mod_timer+0xbc/0xe0 > [] __switch_to+0x370/0x5b0 > [] lock_timer_base+0x2c/0x60 > [] del_timer+0x56/0x70 > [] __generic_unplug_device+0x25/0x30 > [] generic_unplug_device+0x20/0x60 > [] unplug_queue+0x26/0x50 > [] blkif_schedule+0x55a/0x690 > [] blkif_schedule+0x0/0x690 > [] kthread+0xda/0x110 > [] child_rip+0xa/0x12 > [] 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 --000e0cd32ede778e2d048b7124da Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable IIRC during my early experiments with blkback & blktap2, I hit a simila= r error.. tracing through the code, I gathered that the pagemap stuff is us= ed to manage page grants to blktap2 kernel driver . So, the #else (ie !BLKB= K_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 t= o use blkback_pagemap with blktap2? Since the use of blkback_pagemap is con= figurable I tried without it and my system crashed (crash dump attached bel= ow). 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 8000000= 080765027 for l1e_owner=3D0, pg_owner=3D0
(XEN) mm.c:5046:d0 ptwr_emulate: could not get_page_from_l1e()
Unable to handle kernel paging request at ffff8800388f6688 RIP:
=A0[<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>] =A0[<ffffffff803dc7d6>] blktap_m= ap_uaddr_fn+0xa6/0xc0
RSP: e02b:ffff880039d01840 =A0EFLAGS: 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: =A000002af9674c06e0(0000) GS:ffffffff8058c000(0000) knlGS:0000000000000= 000
CS: =A0e033 DS: 0000 ES: 0000
Process blkback.1.sda1 (pid: 4183, threadinfo ffff880039d00000, task ffff88= 003e8cf080)
Stack: =A0ffff8800388f6688 ffff880001fb15d0 ffff880039d018f0 ffffffff802700= 33
=A00000001a00000039 ffff880039d01908 ffffffff803dc730 ffff88003a714080
=A0ffff8800389802b0 00002b218a8d2000 00002b218a8d2000 ffff88003c03b430
Call Trace:
=A0[<ffffffff80270033>] apply_to_page_range+0x4e3/0x590
=A0[<ffffffff803dc730>] blktap_map_uaddr_fn+0x0/0xc0
=A0[<ffffffff803dac01>] blktap_map_uaddr+0x21/0x30
=A0[<ffffffff803db70c>] blktap_device_do_request+0x67c/0xfe0
=A0[<ffffffff8023f36c>] __mod_timer+0xbc/0xe0
=A0[<ffffffff802088b0>] __switch_to+0x370/0x5b0
=A0[<ffffffff8023f1dc>] lock_timer_base+0x2c/0x60
=A0[<ffffffff8023f9c6>] del_timer+0x56/0x70
=A0[<ffffffff80344715>] __generic_unplug_device+0x25/0x30
=A0[<ffffffff803459d0>] generic_unplug_device+0x20/0x60
=A0[<ffffffff803d3196>] unplug_queue+0x26/0x50
=A0[<ffffffff803d3dea>] blkif_schedule+0x55a/0x690
=A0[<ffffffff803d3890>] blkif_schedule+0x0/0x690
=A0[<ffffffff8024b12a>] kthread+0xda/0x110
=A0[<ffffffff8020a428>] child_rip+0xa/0x12
=A0[<ffffffff8024b050>] kthread+0x0/0x110
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Xen-devel@lists.xensource.= com
http://l= ists.xensource.com/xen-devel



--
perception is but an of= fspring of its own self
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