Messages in this thread Patch in this message | | | Date | Wed, 24 Dec 2008 23:35:36 -0800 | From | Andrew Morton <> | Subject | Re: 2.6.28-rc9 panics with crashkernel=256M while booting |
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(cc's added)
On Wed, 24 Dec 2008 13:25:49 +0530 Chandru <chandru@in.ibm.com> wrote:
> On a ppc machine booting linux-2.6.28-rc9 with crashkernel=256M@32M boot > parameter causes the kernel to panic while booting. __Following are the console > messages...
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From: Chandru <chandru@in.ibm.com>
When booted with crashkernel=224M@32M or any memory size less than this, the system boots properly. The following was the observation.. The system comes up with two nodes (0-256M and 256M-4GB). _The crashkernel memory reservation spans across these two nodes. _The mark_reserved_regions_for_nid() in arch/powerpc/mm/numa.c resizes the reserved part of the memory within it as:
_ _ _ _ _ _ if (end_pfn > node_ar.end_pfn) _ _ _ _ _ _ _ _ reserve_size = (node_ar.end_pfn << PAGE_SHIFT) _ _ _ _ _ _ _ _ _ _ - (start_pfn << PAGE_SHIFT);
but the reserve_bootmem_node() in mm/bootmem.c raises the pfn value of end
_ _ end = PFN_UP(physaddr + size);
This causes end to get a value past the last page in the 0-256M node. _Again when reserve_bootmem_node() returns, _mark_reserved_regions_for_nid() loops around to set the rest of the crashkernel memory in the next node as reserved. _ It references NODE_DATA(node_ar.nid) and this causes another 'Oops: kernel access of bad area' problem. The following changes made the system to boot with any amount of crashkernel memory size.
Signed-off-by: Chandru S <chandru@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
arch/powerpc/mm/numa.c | 7 ++++--- mm/bootmem.c | 4 ++++ 2 files changed, 8 insertions(+), 3 deletions(-)
diff -puN arch/powerpc/mm/numa.c~2628-rc9-panics-with-crashkernel=256m-while-booting arch/powerpc/mm/numa.c --- a/arch/powerpc/mm/numa.c~2628-rc9-panics-with-crashkernel=256m-while-booting +++ a/arch/powerpc/mm/numa.c @@ -995,10 +995,11 @@ void __init do_init_bootmem(void) start_pfn, end_pfn); free_bootmem_with_active_regions(nid, end_pfn); + } + + for_each_online_node(nid) { /* - * Be very careful about moving this around. Future - * calls to careful_allocation() depend on this getting - * done correctly. + * Be very careful about moving this around. */ mark_reserved_regions_for_nid(nid); sparse_memory_present_with_active_regions(nid); diff -puN mm/bootmem.c~2628-rc9-panics-with-crashkernel=256m-while-booting mm/bootmem.c --- a/mm/bootmem.c~2628-rc9-panics-with-crashkernel=256m-while-booting +++ a/mm/bootmem.c @@ -375,10 +375,14 @@ int __init reserve_bootmem_node(pg_data_ unsigned long size, int flags) { unsigned long start, end; + bootmem_data_t *bdata = pgdat->bdata; start = PFN_DOWN(physaddr); end = PFN_UP(physaddr + size); + if (end > bdata->node_low_pfn) + end = bdata->node_low_pfn; + return mark_bootmem_node(pgdat->bdata, start, end, 1, flags); } _
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