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.
Signed-off-by: Laura Abbott <lauraa@xxxxxxxxxxxxxx>
Reported-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
Srinivas, can you test this version of the patch?
---
mm/page_alloc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7633c50..33cef00 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5014,6 +5014,7 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat)
if (!pgdat->node_mem_map) {
unsigned long size, start, end;
struct page *map;
+ unsigned long offset = 0;
/*
* The zone's endpoints aren't required to be MAX_ORDER
@@ -5021,6 +5022,8 @@ 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);
+ if (!IS_ENABLED(CONFIG_FLATMEM))
+ offset = pgdat->node_start_pfn - start;
end = pgdat_end_pfn(pgdat);
end = ALIGN(end, MAX_ORDER_NR_PAGES);
size = (end - start) * sizeof(struct page);
@@ -5028,7 +5031,7 @@ 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
/*
--
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