On 03/14/2015 01:08 AM, Laura Abbott wrote:
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>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>