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83 lines
2.8 KiB
Diff
83 lines
2.8 KiB
Diff
From: Tobias Wolf <dev-NTEO@vplace.de>
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Subject: mm: Fix alloc_node_mem_map with ARCH_PFN_OFFSET calculation
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An rt288x (ralink) based router (Belkin F5D8235 v1) does not boot with any
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kernel beyond version 4.3 resulting in:
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BUG: Bad page state in process swapper pfn:086ac
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bisect resulted in:
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a1c34a3bf00af2cede839879502e12dc68491ad5 is the first bad commit
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commit a1c34a3bf00af2cede839879502e12dc68491ad5
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Author: Laura Abbott <laura@labbott.name>
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Date: Thu Nov 5 18:48:46 2015 -0800
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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
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bottom 2MB on an ARM based IFC6410 board
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BUG: Bad page state in process swapper pfn:fffa8
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page:ef7fb500 count:0 mapcount:0 mapping: (null) index:0x0
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flags: 0x96640253(locked|error|dirty|active|arch_1|reclaim|mlocked)
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page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
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bad because of flags:
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flags: 0x200041(locked|active|mlocked)
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Modules linked in:
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CPU: 0 PID: 0 Comm: swapper Not tainted 3.19.0-rc3-00007-g412f9ba-dirty
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#816
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Hardware name: Qualcomm (Flattened Device Tree)
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unwind_backtrace
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show_stack
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dump_stack
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bad_page
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free_pages_prepare
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free_hot_cold_page
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__free_pages
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free_highmem_page
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mem_init
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start_kernel
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Disabling lock debugging due to kernel taint
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[...]
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:040000 040000 2de013c372345fd471cd58f0553c9b38b0ef1cc4
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0a8156f848733dfa21e16c196dfb6c0a76290709 M mm
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This fix for ARM does not account ARCH_PFN_OFFSET for mem_map as later used by
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page_to_pfn anymore.
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The following output was generated with two hacked in printk statements:
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printk("before %p vs. %p or %p\n", mem_map, mem_map - offset, mem_map -
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(pgdat->node_start_pfn - ARCH_PFN_OFFSET));
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if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
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mem_map -= offset + (pgdat->node_start_pfn - ARCH_PFN_OFFSET);
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printk("after %p\n", mem_map);
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Output:
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[ 0.000000] before 8861b280 vs. 8861b280 or 8851b280
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[ 0.000000] after 8851b280
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As seen in the first line mem_map with subtraction of offset does not equal the
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mem_map after subtraction of ARCH_PFN_OFFSET.
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After adding the offset of ARCH_PFN_OFFSET as well to mem_map as the
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previously calculated offset is zero for the named platform it is able to boot
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4.4 and 4.9-rc7 again.
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Signed-off-by: Tobias Wolf <dev-NTEO@vplace.de>
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---
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--- a/mm/page_alloc.c
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+++ b/mm/page_alloc.c
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@@ -6855,7 +6855,7 @@ static void __ref alloc_node_mem_map(str
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mem_map = NODE_DATA(0)->node_mem_map;
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#if defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) || defined(CONFIG_FLATMEM)
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if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
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- mem_map -= offset;
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+ mem_map -= offset + (pgdat->node_start_pfn - ARCH_PFN_OFFSET);
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#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
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}
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#endif
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