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authorLaurent Dufour <ldufour@linux.vnet.ibm.com>2014-02-24 16:30:55 (GMT)
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-02-28 07:06:25 (GMT)
commitf5295bd8ea8a65dc5eac608b151386314cb978f1 (patch)
tree826f84e36044824ce00d8af118afc720078e37e8 /arch/powerpc
parent41dd03a94c7d408d2ef32530545097f7d1befe5c (diff)
powerpc/crashdump : Fix page frame number check in copy_oldmem_page
In copy_oldmem_page, the current check using max_pfn and min_low_pfn to decide if the page is backed or not, is not valid when the memory layout is not continuous. This happens when running as a QEMU/KVM guest, where RTAS is mapped higher in the memory. In that case max_pfn points to the end of RTAS, and a hole between the end of the kdump kernel and RTAS is not backed by PTEs. As a consequence, the kdump kernel is crashing in copy_oldmem_page when accessing in a direct way the pages in that hole. This fix relies on the memblock's service memblock_is_region_memory to check if the read page is part or not of the directly accessible memory. Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> Tested-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> CC: <stable@vger.kernel.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/crash_dump.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 11c1d06..7a13f37 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -98,17 +98,19 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset, int userbuf)
{
void *vaddr;
+ phys_addr_t paddr;
if (!csize)
return 0;
csize = min_t(size_t, csize, PAGE_SIZE);
+ paddr = pfn << PAGE_SHIFT;
- if ((min_low_pfn < pfn) && (pfn < max_pfn)) {
- vaddr = __va(pfn << PAGE_SHIFT);
+ if (memblock_is_region_memory(paddr, csize)) {
+ vaddr = __va(paddr);
csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
} else {
- vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0);
+ vaddr = __ioremap(paddr, PAGE_SIZE, 0);
csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
iounmap(vaddr);
}

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