Re: [BISECTED REGRESSION] Xen: OOPSes on heavy block IO on 2.6.30-master

[Jeremy Fitzhardinge <jeremy@goop.org>]

Bryan Donlan wrote:
> I've bisected this problem down to the following commit;
> unfortunately, there were some rather hairy interdependencies after
> that point, so I wasn't able to test reverting it on top of master:
> commit 93dbda7cbcd70a0bd1a99f39f44a9ccde8ab9040
> Author: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> Date:   Thu Feb 26 17:35:44 2009 -0800
>   

Thanks for going to the trouble of bisecting this, but I'd just fixed 
this bug :/

The patch below should fix it.

Thanks again,
    J

>From f26499cadfd057e4377e92ba680e16fa7bdf9422 Mon Sep 17 00:00:00 2001
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Date: Tue, 5 May 2009 13:08:42 -0700
Subject: [PATCH] xen/i386: reserve Xen pagetables

The Xen pagetables are no longer implicitly reserved as part of the other
i386_start_kernel reservations, so make sure we explicitly reserve them.
This prevents them from being released into the general kernel free page
pool and reused.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 0e13477..801d042 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1799,6 +1799,11 @@ __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd,
 
 	pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(swapper_pg_dir)));
 
+	reserve_early(__pa(xen_start_info->pt_base),
+		      __pa(xen_start_info->pt_base +
+			   xen_start_info->nr_pt_frames * PAGE_SIZE),
+		      "XEN PAGETABLES");
+
 	return swapper_pg_dir;
 }
 #endif	/* CONFIG_X86_64 */