x86, mm: Make DEBUG_VIRTUAL work earlier in boot (a25b9316) · Commits · 戴 / test

The KVM code has some repeated bugs in it around use of __pa() on per-cpu data. Those data are not in an area on which using __pa() is valid. However, they are also called early enough in boot that __vmalloc_start_set is not set, and thus the CONFIG_DEBUG_VIRTUAL debugging does not catch them. This adds a check to also verify __pa() calls against max_low_pfn, which we can use earler in boot than is_vmalloc_addr(). However, if we are super-early in boot, max_low_pfn=0 and this will trip on every call, so also make sure that max_low_pfn is set before we try to use it. With this patch applied, CONFIG_DEBUG_VIRTUAL will actually catch the bug I was chasing (and fix later in this series). I'd love to find a generic way so that any __pa() call on percpu areas could do a BUG_ON(), but there don't appear to be any nice and easy ways to check if an address is a percpu one. Anybody have ideas on a way to do this? Signed-off-by:

Dave Hansen <dave@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20130122212430.F46F8159@kernel.stglabs.ibm.com Signed-off-by:

H. Peter Anvin <hpa@linux.intel.com>

arch/x86/mm/numa.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -219,7 +219,7 @@ static void __init setup_node_data(int nid, u64 start, u64 end)
		*/
		nd = alloc_remap(nid, nd_size);
		if (nd) {
		nd_pa = __pa(nd);
		nd_pa = __phys_addr_nodebug(nd);
		remapped = true;
		} else {
		nd_pa = memblock_alloc_nid(nd_size, SMP_CACHE_BYTES, nid);

arch/x86/mm/pat.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -560,10 +560,10 @@ int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags)
		{
		unsigned long id_sz;

		if (base >= __pa(high_memory))
		if (base > __pa(high_memory-1))
		return 0;

		id_sz = (__pa(high_memory) < base + size) ?
		id_sz = (__pa(high_memory-1) <= base + size) ?
		__pa(high_memory) - base :
		size;

arch/x86/mm/physaddr.c

+8 −1

Original line number	Diff line number	Diff line
		#include <linux/bootmem.h>
		#include <linux/mmdebug.h>
		#include <linux/module.h>
		#include <linux/mm.h>
		@@ -68,10 +69,16 @@ EXPORT_SYMBOL(__virt_addr_valid);
		#ifdef CONFIG_DEBUG_VIRTUAL
		unsigned long __phys_addr(unsigned long x)
		{
		unsigned long phys_addr = x - PAGE_OFFSET;
		/* VMALLOC_* aren't constants */
		VIRTUAL_BUG_ON(x < PAGE_OFFSET);
		VIRTUAL_BUG_ON(__vmalloc_start_set && is_vmalloc_addr((void *) x));
		return x - PAGE_OFFSET;
		/* max_low_pfn is set early, but not _that_ early */
		if (max_low_pfn) {
		VIRTUAL_BUG_ON((phys_addr >> PAGE_SHIFT) > max_low_pfn);
		BUG_ON(slow_virt_to_phys((void *)x) != phys_addr);
		}
		return phys_addr;
		}
		EXPORT_SYMBOL(__phys_addr);
		#endif

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