Re: 05e0caad3b7bd0d0fbeff980bca22f186241a501 breaks ia64 kdump

[mel@skynet.ie (Mel Gorman)]

On (12/12/06 18:10), Horms didst pronounce:
> On Mon, Nov 20, 2006 at 09:40:32AM +0800, Zou, Nanhai wrote:
> > > -----Original Message-----
> > > From: Luck, Tony
> > > Sent: 2006?$BG/11?$B7n17?$BF| 1:36
> > > To: Zou, Nanhai; 'Mel Gorman'
> > > Cc: 'Horms'; 'Andy Whitcroft'; 'Linux-IA64'; 'Bob Picco'; 'Andrew Morton';
> > > 'Dave Hansen'; 'Andi Kleen'; 'Benjamin Herrenschmidt'; 'Paul Mackerras';
> > > 'Keith Mannthey'; 'KAMEZAWA Hiroyuki'; 'Yasunori Goto'; 'Khalid Aziz'
> > > Subject: RE: 05e0caad3b7bd0d0fbeff980bca22f186241a501 breaks ia64 kdump
> > > 
> > > 
> > > > I think that depends on the init value of memmap, if they
> > > > are all zero, free_pages_check will be happy and not report
> > > > any thing. So I guess we may see this bug in normal kernel
> > > > with a warm reboot, or with a machine which PROM does not
> > > > clear memory to all zero.
> > > 
> > > I don't think there is any requirement that PROM clear memory
> > > to zero ... if the kernel is making that assumption anywhere,
> > > then this is a bug.  I thought that the initialization code
> > > wrote to each of the fields of the page struct that it needed
> > > to (certainly ->count and ->flags are set by __free_pages_bootmem,
> > > but I'm not so sure about ->mapping ... which free_pages_check()
> > > looks at).
> > >
> >   Yes, so the add_active_range in discontigmem need fix. 
> >   I think Bob's patch is ok, it is almost the same as mine except the CONFIG_KEXEC part. So we may first include Bob's patch, I will add CONFIG_KEXEC part after KEXEC_KDUMP patch is in mainstream.
> 
> Now that ia64 kexec/kdump has been merged into Linus tree this
> really ought to be fixed. What is the best way forward?
> 

Sorry for the delay in responding. I was ill all of last week and offline as
a result. First, can you confirm the problem still exist? Assuming it does,
does Bob's patch fix it? A compile-tested rebase against 2.6.20-rc1-mm1 of
the patch is posted below for your convenience. I don'y have access to an
ia64 machine right now to boot test it.

>>> Begin Bob's patch

While pursuing and unrelated issue with 64Mb granules I noticed a problem
related to inconsistent use of add_active_range. There doesn't appear any
reason to me why FLATMEM versus DISCONTIG_MEM should register memory
to add_active_range with different code. So I've changed the code into
a common implementation. 

The other subtle issue fixed by this patch was calling add_active_range
in count_node_pages before granule aligning is performed. We were lucky with
16MB granules but not so with 64MB granules. count_node_pages has reserved
regions filtered out and as a consequence linked kernel text and data
aren't covered by calls to count_node_pages. So linked kernel regions
wasn't reported to add_active_regions. This resulted in free_initmem causing
numerous bad_page reports. This won't occur with this patch because now
all known memory regions are reported by register_active_ranges.

Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Bob Picco <bob.picco@hp.com>

 arch/ia64/mm/discontig.c   |    4 +++-
 arch/ia64/mm/init.c        |   18 ++++++++++++++++--
 include/asm-ia64/meminit.h |    3 ++-
 3 files changed, 21 insertions(+), 4 deletions(-)

diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.20-rc1-mm1-clean/arch/ia64/mm/discontig.c linux-2.6.20-rc1-mm1-register_all_memory/arch/ia64/mm/discontig.c
--- linux-2.6.20-rc1-mm1-clean/arch/ia64/mm/discontig.c	2006-12-18 14:12:18.000000000 +0000
+++ linux-2.6.20-rc1-mm1-register_all_memory/arch/ia64/mm/discontig.c	2006-12-18 14:39:28.000000000 +0000
@@ -475,6 +475,9 @@ void __init find_memory(void)
 			node_clear(node, memory_less_mask);
 			mem_data[node].min_pfn = ~0UL;
 		}
+
+	efi_memmap_walk(register_active_ranges, NULL);
+
 	/*
 	 * Initialize the boot memory maps in reverse order since that's
 	 * what the bootmem allocator expects
@@ -656,7 +659,6 @@ static __init int count_node_pages(unsig
 {
 	unsigned long end = start + len;
 
-	add_active_range(node, start >> PAGE_SHIFT, end >> PAGE_SHIFT);
 	mem_data[node].num_physpages += len >> PAGE_SHIFT;
 #ifdef CONFIG_ZONE_DMA
 	if (start <= __pa(MAX_DMA_ADDRESS))
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.20-rc1-mm1-clean/arch/ia64/mm/init.c linux-2.6.20-rc1-mm1-register_all_memory/arch/ia64/mm/init.c
--- linux-2.6.20-rc1-mm1-clean/arch/ia64/mm/init.c	2006-12-14 01:14:23.000000000 +0000
+++ linux-2.6.20-rc1-mm1-register_all_memory/arch/ia64/mm/init.c	2006-12-18 14:42:40.000000000 +0000
@@ -594,13 +594,27 @@ find_largest_hole (u64 start, u64 end, v
 	return 0;
 }
 
+#endif /* CONFIG_VIRTUAL_MEM_MAP */
+
 int __init
 register_active_ranges(u64 start, u64 end, void *arg)
 {
-	add_active_range(0, __pa(start) >> PAGE_SHIFT, __pa(end) >> PAGE_SHIFT);
+	int nid = paddr_to_nid(__pa(start));
+
+	if (nid < 0)
+		nid = 0;
+#ifdef CONFIG_KEXEC
+	if (start > crashk_res.start && start < crashk_res.end)
+		start = max(start, crashk_res.end);
+	if (end > crashk_res.start && end < crashk_res.end)
+		end = min(end, crashk_res.start);
+#endif
+
+	if (start < end)
+		add_active_range(nid, __pa(start) >> PAGE_SHIFT,
+			__pa(end) >> PAGE_SHIFT);
 	return 0;
 }
-#endif /* CONFIG_VIRTUAL_MEM_MAP */
 
 static int __init
 count_reserved_pages (u64 start, u64 end, void *arg)
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.20-rc1-mm1-clean/include/asm-ia64/meminit.h linux-2.6.20-rc1-mm1-register_all_memory/include/asm-ia64/meminit.h
--- linux-2.6.20-rc1-mm1-clean/include/asm-ia64/meminit.h	2006-12-14 01:14:23.000000000 +0000
+++ linux-2.6.20-rc1-mm1-register_all_memory/include/asm-ia64/meminit.h	2006-12-18 14:39:28.000000000 +0000
@@ -51,12 +51,13 @@ extern void efi_memmap_init(unsigned lon
 
 #define IGNORE_PFN0	1	/* XXX fix me: ignore pfn 0 until TLB miss handler is updated... */
 
+extern int register_active_ranges (u64 start, u64 end, void *arg);
+
 #ifdef CONFIG_VIRTUAL_MEM_MAP
 # define LARGE_GAP	0x40000000 /* Use virtual mem map if hole is > than this */
   extern unsigned long vmalloc_end;
   extern struct page *vmem_map;
   extern int find_largest_hole (u64 start, u64 end, void *arg);
-  extern int register_active_ranges (u64 start, u64 end, void *arg);
   extern int create_mem_map_page_table (u64 start, u64 end, void *arg);
   extern int vmemmap_find_next_valid_pfn(int, int);
 #else