>Hello Atsushi,
>
>I debugged my problem a bit further and tried to implement
>a function that gets the maximum page frame number from the
>Linux kernel memory management structures.
>
>I am no memory management expert, so the following patch probably
>is not complete, but at least for my setup it worked.
The patch looks good for your case, but I don't think it's a proper
approach for this problem.
Now, I think this is a problem of get_mm_sparsemem() in makedumpfile.
To say in more detail, the problem is "wrong calculating the address
of unused mem_map".
Looking at the log you sent, some addresses of mem_map corresponding
to unused pages look invalid like below:
mem_map (256)
mem_map : 80000c0002018
pfn_start : 1000000
pfn_end : 1010000
mem_map (257)
mem_map : 800001840400000
pfn_start : 1010000
pfn_end : 1020000
...
mem_map (544)
mem_map : a82400012f14fffc
pfn_start : 2200000
pfn_end : 2210000
...(and more)
However, makedumpfile should calculate such unused mem_map addresses
as 0(NOT_MEMMAP_ADDR). Actually it works as expected at least in my
environment(x86_64):
...
mem_map (16)
mem_map : 0
pfn_start : 80000
pfn_end : 88000
mem_map (17)
mem_map : 0
pfn_start : 88000
pfn_end : 90000
...
makedumpfile get the address from mem_section.section_mem_map,
it will be initialized with zero:
[CONFIG_SPARSEMEM_EXTREAM]
paging_init()
sparse_memory_present_with_active_regions()
memory_present()
sparse_index_init()
sparse_index_alloc() // allocate mem_section with kzalloc()
makedumpfile assumes the value of unused mem_section will remain as 0,
but I suspect this assumption may be broken in your environment.
Moreover, if it's true, the problem will happen when memmap= parameter
is specified even if max_mapnr is correct.
This is because the unused pages created by memmap= will be placed
below max_mapnr and its mem_map will be calculated wrongly by
get_mm_sparsemem().
I'll continue to investigate to find better solution for this problem,
any comments are helpful.
Thanks
Atsushi Kumagai
>Michael
>---
> makedumpfile.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 58 insertions(+)
>
>--- a/makedumpfile.c
>+++ b/makedumpfile.c
>@@ -2029,6 +2029,48 @@ pgdat4:
> return SYMBOL(contig_page_data);
> }
>
>+int
>+get_max_pfn(void)
>+{
>+ unsigned long pgdat, node_start_pfn, node_spanned_pages, max_pfn = 0;
>+ int num_nodes, node;
>+
>+ if ((node = next_online_node(0)) < 0) {
>+ ERRMSG("Can't get next online node.\n");
>+ return FALSE;
>+ }
>+ if (!(pgdat = next_online_pgdat(node))) {
>+ ERRMSG("Can't get pgdat list.\n");
>+ return FALSE;
>+ }
>+ for (num_nodes = 1; num_nodes <= vt.numnodes; num_nodes++) {
>+ if (!readmem(VADDR, pgdat + OFFSET(pglist_data.node_start_pfn),
>+ &node_start_pfn, sizeof node_start_pfn)) {
>+ ERRMSG("Can't get node_start_pfn.\n");
>+ return FALSE;
>+ }
>+ if (!readmem(VADDR,
>+ pgdat + OFFSET(pglist_data.node_spanned_pages),
>+ &node_spanned_pages, sizeof node_spanned_pages)) {
>+ ERRMSG("Can't get node_spanned_pages.\n");
>+ return FALSE;
>+ }
>+ max_pfn = MAX(max_pfn, (node_start_pfn + node_spanned_pages));
>+ if (num_nodes < vt.numnodes) {
>+ if ((node = next_online_node(node + 1)) < 0) {
>+ ERRMSG("Can't get next online node.\n");
>+ return FALSE;
>+ } else if (!(pgdat = next_online_pgdat(node))) {
>+ ERRMSG("Can't determine pgdat list (node %d).\n",
>+ node);
>+ return FALSE;
>+ }
>+ }
>+ }
>+ info->max_mapnr = max_pfn;
>+ return TRUE;
>+}
>+
> void
> dump_mem_map(unsigned long long pfn_start,
> unsigned long long pfn_end, unsigned long mem_map, int num_mm)
>@@ -2853,6 +2908,9 @@ out:
> if (!get_numnodes())
> return FALSE;
>
>+ if (!get_max_pfn())
>+ return FALSE;
>+
> if (!get_mem_map())
> return FALSE;
>
>
>
>_______________________________________________
>kexec mailing list
>kexec at lists.infradead.org
>http://lists.infradead.org/mailman/listinfo/kexec
