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mm: Don't offset memmap for flatmem

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Srinivas Kandagatla reported bad page messages when trying to remove the
bottom 2MB on an ARM based IFC6410 board

  BUG: Bad page state in process swapper  pfn:fffa8
  page:ef7fb500 count:0 mapcount:0 mapping:  (null) index:0x0
  flags: 0x96640253(locked|error|dirty|active|arch_1|reclaim|mlocked)
  page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
  bad because of flags:
  flags: 0x200041(locked|active|mlocked)
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 3.19.0-rc3-00007-g412f9ba-dirty #816
  Hardware name: Qualcomm (Flattened Device Tree)
    unwind_backtrace
    show_stack
    dump_stack
    bad_page
    free_pages_prepare
    free_hot_cold_page
    __free_pages
    free_highmem_page
    mem_init
    start_kernel
  Disabling lock debugging due to kernel taint

Removing the lower 2MB made the start of the lowmem zone to no longer be
page block aligned.  IFC6410 uses CONFIG_FLATMEM where alloc_node_mem_map
allocates memory for the mem_map.  alloc_node_mem_map will offset for
unaligned nodes with the assumption the pfn/page translation functions
will account for the offset.  The functions for CONFIG_FLATMEM do not
offset however, resulting in overrunning the memmap array.  Just use the
allocated memmap without any offset when running with CONFIG_FLATMEM to
avoid the overrun.

Signed-off-by: Laura Abbott <[email protected]>
Signed-off-by: Laura Abbott <[email protected]>
Reported-by: Srinivas Kandagatla <[email protected]>
Tested-by: Srinivas Kandagatla <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Tested-by: Bjorn Andersson <[email protected]>
Cc: Santosh Shilimkar <[email protected]>
Cc: Russell King <[email protected]>
Cc: Kevin Hilman <[email protected]>
Cc: Arnd Bergman <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Andy Gross <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Dave Hansen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Laura Abbott authored and Linus Torvalds committed 2015-11-05 19:34:48 -08:00
1 parent c2d42c16ad
commit a1c34a3bf0
1 file changed
+6 -3
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mm/page_alloc.c
+6 -3
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@@ -5421,6 +5421,8 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat)
static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat)
{
unsigned long __maybe_unused offset = 0;
/* Skip empty nodes */
if (!pgdat->node_spanned_pages)
return;
@@ -5437,6 +5439,7 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat)
* for the buddy allocator to function correctly.
*/
start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
offset = pgdat->node_start_pfn - start;
end = pgdat_end_pfn(pgdat);
end = ALIGN(end, MAX_ORDER_NR_PAGES);
size = (end - start) * sizeof(struct page);
@@ -5444,7 +5447,7 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat)
if (!map)
map = memblock_virt_alloc_node_nopanic(size,
pgdat->node_id);
pgdat->node_mem_map = map + (pgdat->node_start_pfn - start);
pgdat->node_mem_map = map + offset;
}
#ifndef CONFIG_NEED_MULTIPLE_NODES
/*
@@ -5452,9 +5455,9 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat)
*/
if (pgdat == NODE_DATA(0)) {
mem_map = NODE_DATA(0)->node_mem_map;
#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
#if defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) || defined(CONFIG_FLATMEM)
if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
mem_map -= (pgdat->node_start_pfn - ARCH_PFN_OFFSET);
mem_map -= offset;
#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
}
#endif