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Re: [Xen-devel] pvops dom0 work roadmap

from [Konrad Rzeszutek Wilk] [Permanent Link][Original]
To: Gianluca Guida <gianluca.guida@xxxxxxxxxx>
Subject: Re: [Xen-devel] pvops dom0 work roadmap
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Thu, 20 Aug 2009 12:39:48 -0400
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On Thu, Aug 20, 2009 at 04:49:08PM +0100, Gianluca Guida wrote:
> Konrad Rzeszutek Wilk writes:
>  > I will retry this, but in the meantime I am tracking balloon accessing 
> non-existent pages:
> 
> Hm, what tree of dom0 kernel are you using? Is commit

[konrad@phenom linux]$ git checkout origin/rebase/master -b boo
Branch boo set up to track remote branch refs/remotes/origin/rebase/master.
Switched to a new branch 'boo'
[konrad@phenom linux]$ git show  7394b25905929a92e51771b832ee67b70ccebcf0
fatal: bad object 7394b25905929a92e51771b832ee67b70ccebcf0

> 7394b25905929a92e51771b832ee67b70ccebcf0 (Revert "Xen: Allow guest to
> boot ballooned.") there?

What branch is it in?

> 
> The point is that xen_memory_setup should truncate the ram visible in
> the e820 map to xen_start_info->nr_pages, so that the balloon driver
> would never try to add pages on boot.

Sure. This problem is for pages above ->nr_pages.

The loop goes from xen_start_info->nr_pages to max_pfn (which is set to
0x130000000 - the last E820 region for a 4GB machine). In the E820
there is a big gap between 0xcfee0000 to 0x100000000 on which
the ballooon driver tries to loop through and dereferncing
the pages. That fails as it seems the mapping for those pages isn't set.
(I haven't actually verified whether the page table has entries for this
or not, but the 'unable to handle kernel paging request' implies it isnt).

> 
> Thanks,
> Gianluca
> 
> 
>  > 
>  > <BEGIN>
>  > [    0.239963] xen_balloon: Initialising balloon driver.
>  > [    0.240057] xen_ballon: 131072 -> 1245184            <-- added a printk.
>  > [    0.257938] BUG: unable to handle kernel [    0.257938] BUG: unable to 
> handle kernel paging requestpaging request at ffffea0002d80028
>  >  at ffffea0002d80028
>  > [    0.257960] IP:[    0.257960] IP: [<ffffffff81215f7b>] 
> balloon_append+0x13/0x36
>  >  [<ffffffff81215f7b>] balloon_append+0x13/0x36
>  > [    0.257960] PGD 10402067 [    0.257960] PGD 10402067 PUD 10403067 PUD 
> 10403067 PMD 1301a067 PMD 1301a067 PTE 0PTE 0
>  > 
>  > [    0.257960] Oops: 0002 [#1] [    0.257960] Oops: 0002 [#1] SMP SMP
>  > 
>  > [    0.257960] last sysfs file:
>  > [    0.257960] last sysfs file:
>  > [    0.257960] CPU 0 [    0.257960] CPU 0
>  > 
>  > [    0.257960] Modules linked in:[    0.257960] Modules linked in:
>  > 
>  > [    0.257960] Pid: 1, comm: swapper Not tainted 
> 2.6.31-rc5-xen0-23866-g8584ce8-dirty #6 .
>  > [    0.257960] Pid: 1, comm: swapper Not tainted 
> 2.6.31-rc5-xen0-23866-g8584ce8-dirty #6 .
>  > [    0.257960] RIP: e030:[<ffffffff81215f7b>] [    0.257960] RIP: 
> e030:[<ffffffff81215f7b>]  [<ffffffff81215f7b>] balloon_append+0x13/0x36
>  >  [<ffffffff81215f7b>] balloon_append+0x13/0x36
>  > [    0.257960] RSP: e02b:ffff88001fc81e70  EFLAGS: 00010282
>  > [    0.257960] RSP: e02b:ffff88001fc81e70  EFLAGS: 00010282
>  > [    0.257960] RAX: ffffea0002d80028 RBX: 00000000000d0001 RCX: 
> 0000000000000064
>  > [    0.257960] RAX: ffffea0002d80028 RBX: 00000000000d0001 RCX: 
> 0000000000000064
>  > [    0.257960] RDX: ffffea0002d7fff0 RSI: ffffffff810000df RDI: 
> ffffea0002d80000
>  > [    0.257960] RDX: ffffea0002d7fff0 RSI: ffffffff810000df RDI: 
> ffffea0002d80000
>  > [    0.257960] RBP: ffff88001fc81e70 R08: 0000000000000000 R09: 
> ffff88001fc38000
>  > [    0.257960] RBP: ffff88001fc81e70 R08: 0000000000000000 R09: 
> ffff88001fc38000
>  > [    0.257960] R10: ffff88001fc81c20 R11: ffff88001fc81da0 R12: 
> ffffea0002d80038
>  > [    0.257960] R10: ffff88001fc81c20 R11: ffff88001fc81da0 R12: 
> ffffea0002d80038
>  > [    0.257960] R13: ffffffff816e1907 R14: 0000000000000000 R15: 
> 0000000000000000
>  > [    0.257960] R13: ffffffff816e1907 R14: 0000000000000000 R15: 
> 0000000000000000
>  > [    0.257960] FS:  0000000000000000(0000) GS:ffffc90000000000(0000) 
> knlGS:0000000000000000
>  > [    0.257960] FS:  0000000000000000(0000) GS:ffffc90000000000(0000) 
> knlGS:0000000000000000
>  > [    0.257960] CS:  e033 DS: 0000 ES: 0000 CR0: 000000008005003b
>  > [    0.257960] CS:  e033 DS: 0000 ES: 0000 CR0: 000000008005003b
>  > [    0.257960] CR2: ffffea0002d80028 CR3: 0000000001001000 CR4: 
> 0000000000002660
>  > [    0.257960] CR2: ffffea0002d80028 CR3: 0000000001001000 CR4: 
> 0000000000002660
>  > [    0.257960] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
> 0000000000000000
>  > [    0.257960] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
> 0000000000000000
>  > [    0.257960] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 
> 0000000000000400
>  > [    0.257960] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 
> 0000000000000400
>  > [    0.257960] Process swapper (pid: 1, threadinfo ffff88001fc80000, task 
> ffff88001fc78000)
>  > [    0.257960] Process swapper (pid: 1, threadinfo ffff88001fc80000, task 
> ffff88001fc78000)
>  > [    0.257960] Stack:
>  > [    0.257960] Stack:
>  > [    0.257960]  ffff88001fc81ea0[    0.257960]  ffff88001fc81ea0 
> ffffffff816e1ad0 ffffffff816e1ad0 ffff88001fc81ea0 ffff88001fc81ea0 
> ffffffff816e18ad ffffffff816e18ad
>  > 
>  > [    0.257960] <0>[    0.257960] <0> ffffffff817167a8 ffffffff817167a8 
> 0000000000000040 0000000000000040 ffff88001fc81f10 ffff88001fc81f10 
> ffffffff8100a05c ffffffff8100a05c
>  > 
>  > [    0.257960] <0>[    0.257960] <0> ffff88001fc81e00 ffff88001fc81e00 
> ffffffff8108e691 ffffffff8108e691 0000000000003333 0000000000003333 
> ffffffff81110000 ffffffff81110000
>  > 
>  > [    0.257960] Call Trace:
>  > [    0.257960] Call Trace:
>  > [    0.257960]  [<ffffffff816e1ad0>] balloon_init+0x1c9/0x1fd
>  > [    0.257960]  [<ffffffff816e1ad0>] balloon_init+0x1c9/0x1fd
>  > [    0.257960]  [<ffffffff816e18ad>] ? xenbus_probe_frontend_init+0x53/0x59
>  > [    0.257960]  [<ffffffff816e18ad>] ? xenbus_probe_frontend_init+0x53/0x59
>  > [    0.257960]  [<ffffffff8100a05c>] do_one_initcall+0x56/0x136
>  > [    0.257960]  [<ffffffff8100a05c>] do_one_initcall+0x56/0x136
>  > [    0.257960]  [<ffffffff8108e691>] ? register_irq_proc+0xae/0xca
>  > [    0.257960]  [<ffffffff8108e691>] ? register_irq_proc+0xae/0xca
>  > [    0.257960]  [<ffffffff81110000>] ? elf_core_dump+0x81e/0xc29
>  > [    0.257960]  [<ffffffff81110000>] ? elf_core_dump+0x81e/0xc29
>  > [    0.257960]  [<ffffffff816bc9aa>] kernel_init+0x15e/0x1b6
>  > [    0.257960]  [<ffffffff816bc9aa>] kernel_init+0x15e/0x1b6
>  > [    0.257960]  [<ffffffff81012cea>] child_rip+0xa/0x20
>  > [    0.257960]  [<ffffffff81012cea>] child_rip+0xa/0x20
>  > [    0.257960]  [<ffffffff81011ea7>] ? int_ret_from_sys_call+0x7/0x1b
>  > [    0.257960]  [<ffffffff81011ea7>] ? int_ret_from_sys_call+0x7/0x1b
>  > [    0.257960]  [<ffffffff8101265d>] ? retint_restore_args+0x5/0x6
>  > [    0.257960]  [<ffffffff8101265d>] ? retint_restore_args+0x5/0x6
>  > [    0.257960]  [<ffffffff81012ce0>] ? child_rip+0x0/0x20
>  > [    0.257960]  [<ffffffff81012ce0>] ? child_rip+0x0/0x20
>  > [    0.257960] Code: [    0.257960] Code: 55 55 89 89 ff ff 48 48 89 89 e5 
> e5 e8 e8 25 25 32 32 df df ff ff c9 c9 c3 c3 55 55 48 48 89 89 e5 e5 e8 e8 5a 
> 5a 32 32 df df ff ff c9 c9 c3 c3 48 48 8b 8b 15 15 d1 d1 0c 0c 43 43 00 00 48 
> 48 8d 8d 47 47 28 28 55 55 48 48 89 89 e5 e5 48 48 89 89 42 42 08 08 <48> 
> <48> 89 89 57 57 28 28 48 48 c7 c7 40 40 08 08 40 40 6c 6c 64 64 81 81 48 48 
> ff ff 05 05 6a 6a ac ac 60 60 00 00 48 48 ff ff
>  > 
>  > [    0.257960] RIP [    0.257960] RIP  [<ffffffff81215f7b>] 
> balloon_append+0x13/0x36
>  >  [<ffffffff81215f7b>] balloon_append+0x13/0x36
>  > [    0.257960]  RSP <ffff88001fc81e70>
>  > [    0.257960]  RSP <ffff88001fc81e70>
>  > [    0.257960] CR2: ffffea0002d80028
>  > [    0.257960] CR2: ffffea0002d80028
>  > [    0.257960] ---[ end trace 4eaa2a86a8e2da22 ]---
>  > [    0.257960] ---[ end trace 4eaa2a86a8e2da22 ]---
>  > <END>
>  > 
>  > Sorry for the duplicate lines. I think the combination of earlycons and 
> console both pointing
>  > to the Xen console driver is screwing this up.
>  > 
>  > This could be a simple bug with the max_pfn being reset to phantom value:
>  > 
>  > [    0.000000] BIOS-provided physical RAM map:
>  > [    0.000000]  Xen: 0000000000000000 - 000000000009f400 (usable)
>  > [    0.000000]  Xen: 000000000009f400 - 0000000000100000 (reserved)
>  > [    0.000000]  Xen: 0000000000100000 - 00000000cfee0000 (usable)
>  > [    0.000000]  Xen: 00000000cfee0000 - 00000000cfee3000 (ACPI NVS)
>  > [    0.000000]  Xen: 00000000cfee3000 - 00000000cfef0000 (ACPI data)
>  > [    0.000000]  Xen: 00000000cfef0000 - 00000000cff00000 (reserved)
>  > [    0.000000]  Xen: 00000000e0000000 - 00000000f0000000 (reserved)
>  > [    0.000000]  Xen: 00000000fec00000 - 0000000100000000 (reserved)
>  > [    0.000000]  Xen: 0000000100000000 - 0000000130000000 (usable)
>  > [    0.000000] console [xenboot0] enabled
>  > [    0.000000] DMI 2.5 present.
>  > [    0.000000] Phoenix BIOS detected: BIOS may corrupt low RAM, working 
> around it.
>  > [    0.000000] e820 update range: 0000000000000000 - 0000000000010000 
> (usable) ==> (reserved)
>  > [    0.000000] last_pfn = 0x130000 max_arch_pfn = 0x400000000
>  > [    0.000000] max_pfn = 1245184                        <-- Added a printk
>  > [    0.000000] num_physpages: 1245184                   <-- Added a printk
>  > [    0.000000] Searching for max PFN under 4GB          <-- Added a printk
>  > [    0.000000] last_pfn = 0xcfee0 max_arch_pfn = 0x400000000
>  > [    0.000000] max_low_pfn: 851680m                     <-- Added a printk
>  > [    0.000000] Scanning 0 areas for low memory corruption
>  > [    0.000000] modified physical RAM map:
>  > [    0.000000]  modified: 0000000000000000 - 0000000000010000 (reserved)
>  > [    0.000000]  modified: 0000000000010000 - 000000000009f400 (usable)
>  > [    0.000000]  modified: 000000000009f400 - 0000000000100000 (reserved)
>  > [    0.000000]  modified: 0000000000100000 - 00000000cfee0000 (usable)
>  > [    0.000000]  modified: 00000000cfee0000 - 00000000cfee3000 (ACPI NVS)
>  > [    0.000000]  modified: 00000000cfee3000 - 00000000cfef0000 (ACPI data)
>  > [    0.000000]  modified: 00000000cfef0000 - 00000000cff00000 (reserved)
>  > [    0.000000]  modified: 00000000e0000000 - 00000000f0000000 (reserved)
>  > [    0.000000]  modified: 00000000fec00000 - 0000000100000000 (reserved)
>  > [    0.000000]  modified: 0000000100000000 - 0000000130000000 (usable)
>  > [    0.000000] initial memory mapped : 0 - 20000000
>  > 
>  > The machine has 4GB, but somehow the max_pfn is set to point to 5.1GB 
> which is
>  > surely not right. Oh, I am compiling a 64-bit Linux and Xen.
>  > 
>  > _______________________________________________
>  > Xen-devel mailing list
>  > Xen-devel@xxxxxxxxxxxxxxxxxxx
>  > http://lists.xensource.com/xen-devel
> 
> _______________________________________________
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