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| author | David Vrabel <david.vrabel@citrix.com> | 2011-09-13 10:17:32 -0400 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2011-09-13 10:17:32 -0400 |
| commit | e3b73c4a25e9a5705b4ef28b91676caf01f9bc9f (patch) | |
| tree | 969df8ce6993364d0fcddffcd1a96e5dfa5a4c86 /arch/x86 | |
| parent | f10cd522c5fbfec9ae3cc01967868c9c2401ed23 (diff) | |
| download | linux-e3b73c4a25e9a5705b4ef28b91676caf01f9bc9f.tar.bz2 | |
xen/e820: if there is no dom0_mem=, don't tweak extra_pages.
The patch "xen: use maximum reservation to limit amount of usable RAM"
(d312ae878b6aed3912e1acaaf5d0b2a9d08a4f11) breaks machines that
do not use 'dom0_mem=' argument with:
reserve RAM buffer: 000000133f2e2000 - 000000133fffffff
(XEN) mm.c:4976:d0 Global bit is set to kernel page fffff8117e
(XEN) domain_crash_sync called from entry.S
(XEN) Domain 0 (vcpu#0) crashed on cpu#0:
...
The reason being that the last E820 entry is created using the
'extra_pages' (which is based on how many pages have been freed).
The mentioned git commit sets the initial value of 'extra_pages'
using a hypercall which returns the number of pages (if dom0_mem
has been used) or -1 otherwise. If the later we return with
MAX_DOMAIN_PAGES as basis for calculation:
return min(max_pages, MAX_DOMAIN_PAGES);
and use it:
extra_limit = xen_get_max_pages();
if (extra_limit >= max_pfn)
extra_pages = extra_limit - max_pfn;
else
extra_pages = 0;
which means we end up with extra_pages = 128GB in PFNs (33554432)
- 8GB in PFNs (2097152, on this specific box, can be larger or smaller),
and then we add that value to the E820 making it:
Xen: 00000000ff000000 - 0000000100000000 (reserved)
Xen: 0000000100000000 - 000000133f2e2000 (usable)
which is clearly wrong. It should look as so:
Xen: 00000000ff000000 - 0000000100000000 (reserved)
Xen: 0000000100000000 - 000000027fbda000 (usable)
Naturally this problem does not present itself if dom0_mem=max:X
is used.
CC: stable@kernel.org
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/xen/setup.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index ff3dfa176814..09688eb4a899 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -305,10 +305,12 @@ char * __init xen_memory_setup(void) sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map); extra_limit = xen_get_max_pages(); - if (extra_limit >= max_pfn) - extra_pages = extra_limit - max_pfn; - else - extra_pages = 0; + if (max_pfn + extra_pages > extra_limit) { + if (extra_limit > max_pfn) + extra_pages = extra_limit - max_pfn; + else + extra_pages = 0; + } extra_pages += xen_return_unused_memory(xen_start_info->nr_pages, &e820); |