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mm: Don't offset memmap for flatmem 

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 <laura@labbott.name>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Reported-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Cc: Santosh Shilimkar <ssantosh@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Arnd Bergman <arnd@arndb.de>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Andy Gross <agross@codeaurora.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Laura Abbott 2015-11-05 18:48:46 -08:00 committed by Linus Torvalds
parent c2d42c16ad
commit a1c34a3bf0
1 changed files with 6 additions and 3 deletions
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9
mm/page_alloc.c
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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