nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/b3c5db79eb72fb068809052a9b53ce7282583c0b
commit b3c5db79eb72fb068809052a9b53ce7282583c0b
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Wed Nov 30 16:58:41 2016 +0100
kernel: Fix alloc_node_mem_map with ARCH_PFN_OFFSET
Fixes a bug that affects rt288x
Signed-off-by: Tobias Wolf <github-NTEO at vplace.de>
Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
...c_node_mem_map-with-ARCH_PFN_OFFSET-calcu.patch | 86 ++++++++++++++++++++++
1 file changed, 86 insertions(+)
diff --git a/target/linux/generic/patches-4.4/103-Fix-alloc_node_mem_map-with-ARCH_PFN_OFFSET-calcu.patch b/target/linux/generic/patches-4.4/103-Fix-alloc_node_mem_map-with-ARCH_PFN_OFFSET-calcu.patch
new file mode 100644
index 0000000..b2daa17
--- /dev/null
+++ b/target/linux/generic/patches-4.4/103-Fix-alloc_node_mem_map-with-ARCH_PFN_OFFSET-calcu.patch
@@ -0,0 +1,86 @@
+From: Tobias Wolf <dev-NTEO at vplace.de>
+Date: Wed, 30 Nov 2016 09:16:41 +0100
+Subject: [PATCH] mm: Fix alloc_node_mem_map with ARCH_PFN_OFFSET
+ calculation
+
+Dear folks,
+
+An rt288x (ralink) based router (Belkin F5D8235 v1) does not boot with any
+kernel beyond version 4.3 resulting in:
+
+BUG: Bad page state in process swapper pfn:086ac
+
+bisect resulted in:
+
+a1c34a3bf00af2cede839879502e12dc68491ad5 is the first bad commit
+commit a1c34a3bf00af2cede839879502e12dc68491ad5
+Author: Laura Abbott <laura at labbott.name>
+Date: Thu Nov 5 18:48:46 2015 -0800
+
+ 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
+ [...]
+:040000 040000 2de013c372345fd471cd58f0553c9b38b0ef1cc4
+0a8156f848733dfa21e16c196dfb6c0a76290709 M mm
+
+This fix for ARM does not account ARCH_PFN_OFFSET for mem_map as later used by
+page_to_pfn anymore.
+
+The following output was generated with two hacked in printk statements:
+
+printk("before %p vs. %p or %p\n", mem_map, mem_map - offset, mem_map -
+(pgdat->node_start_pfn - ARCH_PFN_OFFSET));
+ if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
+ mem_map -= offset + (pgdat->node_start_pfn - ARCH_PFN_OFFSET);
+printk("after %p\n", mem_map);
+
+Output:
+
+[ 0.000000] before 8861b280 vs. 8861b280 or 8851b280
+[ 0.000000] after 8851b280
+
+As seen in the first line mem_map with subtraction of offset does not equal the
+mem_map after subtraction of ARCH_PFN_OFFSET.
+
+After adding the offset of ARCH_PFN_OFFSET as well to mem_map as the
+previously calculated offset is zero for the named platform it is able to boot
+4.4 and 4.9-rc7 again.
+
+Signed-off-by: Tobias Wolf <dev-NTEO at vplace.de>
+---
+
+--- a/mm/page_alloc.c
++++ b/mm/page_alloc.c
+@@ -5326,7 +5326,7 @@ static void __init_refok alloc_node_mem_
+ mem_map = NODE_DATA(0)->node_mem_map;
+ #if defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) || defined(CONFIG_FLATMEM)
+ if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
+- mem_map -= offset;
++ mem_map -= offset + (pgdat->node_start_pfn - ARCH_PFN_OFFSET);
+ #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
+ }
+ #endif