The patch titled
Subject: mm: don't offset memmap for flatmem
has been added to the -mm tree. Its filename is
mm-dont-offset-memmap-for-flatmem.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-dont-offset-memmap-for-flatmem.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-dont-offset-memmap-for-flatmem.patch
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------------------------------------------------------
From: Laura Abbott <lauraa@xxxxxxxxxxxxxx>
Subject: 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)
[<c0218280>] (unwind_backtrace) from [<c0212be8>] (show_stack+0x20/0x24)
[<c0212be8>] (show_stack) from [<c0af7124>] (dump_stack+0x80/0x9c)
[<c0af7124>] (dump_stack) from [<c0301570>] (bad_page+0xc8/0x128)
[<c0301570>] (bad_page) from [<c03018a8>] (free_pages_prepare+0x168/0x1e0)
[<c03018a8>] (free_pages_prepare) from [<c030369c>] (free_hot_cold_page+0x3c/0x174)
[<c030369c>] (free_hot_cold_page) from [<c0303828>] (__free_pages+0x54/0x58)
[<c0303828>] (__free_pages) from [<c030395c>] (free_highmem_page+0x38/0x88)
[<c030395c>] (free_highmem_page) from [<c0f62d5c>] (mem_init+0x240/0x430)
[<c0f62d5c>] (mem_init) from [<c0f5db3c>] (start_kernel+0x1e4/0x3c8)
[<c0f5db3c>] (start_kernel) from [<80208074>] (0x80208074)
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.
The thread got too deep so I split this out into a new thread.
See http://marc.info/?l=linux-mm&m=142188852025672&w=2 for previous
thread discussion, last comment by Vlastimil
http://marc.info/?l=linux-mm&m=142505070430844&w=2
Signed-off-by: Laura Abbott <lauraa@xxxxxxxxxxxxxx>
Reported-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Santosh Shilimkar <ssantosh@xxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: Kevin Hilman <khilman@xxxxxxxxxx>
Cc: Arnd Bergman <arnd@xxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Cc: Kumar Gala <galak@xxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff -puN mm/page_alloc.c~mm-dont-offset-memmap-for-flatmem mm/page_alloc.c
--- a/mm/page_alloc.c~mm-dont-offset-memmap-for-flatmem
+++ a/mm/page_alloc.c
@@ -4996,6 +4996,8 @@ static void __paginginit free_area_init_
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;
@@ -5012,6 +5014,7 @@ static void __init_refok alloc_node_mem_
* 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);
@@ -5019,7 +5022,7 @@ static void __init_refok alloc_node_mem_
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
/*
@@ -5027,10 +5030,12 @@ static void __init_refok alloc_node_mem_
*/
if (pgdat == NODE_DATA(0)) {
mem_map = NODE_DATA(0)->node_mem_map;
-#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
- if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
- mem_map -= (pgdat->node_start_pfn - ARCH_PFN_OFFSET);
-#endif /* 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 -= offset;
+ VM_BUG_ON(page_to_pfn(mem_map) != pgdat->node_start_pfn);
+ }
+#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP || CONFIG_FLATMEM */
}
#endif
#endif /* CONFIG_FLAT_NODE_MEM_MAP */
_
Patches currently in -mm which might be from lauraa@xxxxxxxxxxxxxx are
mm-cma-debugfs-interface.patch
mm-cma-allocation-trigger.patch
mm-cma-release-trigger.patch
mm-cma-allocation-trigger-fix.patch
cma-debug-document-new-debugfs-interface.patch
mm-dont-offset-memmap-for-flatmem.patch
seccomp-allow-compat-sigreturn-overrides.patch
arm-use-asm-generic-for-seccomph.patch
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