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Subject[PATCH 4.14 05/54] xtensa: fix high memory/reserved memory collision
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Max Filippov <jcmvbkbc@gmail.com>

commit 6ac5a11dc674bc5016ea716e8082fff61f524dc1 upstream.

Xtensa memory initialization code frees high memory pages without
checking whether they are in the reserved memory regions or not. That
results in invalid value of totalram_pages and duplicate page usage by
CMA and highmem. It produces a bunch of BUGs at startup looking like
this:

BUG: Bad page state in process swapper pfn:70800
page:be60c000 count:0 mapcount:-127 mapping: (null) index:0x1
flags: 0x80000000()
raw: 80000000 00000000 00000001 ffffff80 00000000 be60c014 be60c014 0000000a
page dumped because: nonzero mapcount
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Tainted: G B 4.16.0-rc1-00015-g7928b2cbe55b-dirty #23
Stack:
bd839d33 00000000 00000018 ba97b64c a106578c bd839d70 be60c000 00000000
a1378054 bd86a000 00000003 ba97b64c a1066166 bd839da0 be60c000 ffe00000
a1066b58 bd839dc0 be504000 00000000 000002f4 bd838000 00000000 0000001e
Call Trace:
[<a1065734>] bad_page+0xac/0xd0
[<a106578c>] free_pages_check_bad+0x34/0x4c
[<a1066166>] __free_pages_ok+0xae/0x14c
[<a1066b58>] __free_pages+0x30/0x64
[<a1365de5>] init_cma_reserved_pageblock+0x35/0x44
[<a13682dc>] cma_init_reserved_areas+0xf4/0x148
[<a10034b8>] do_one_initcall+0x80/0xf8
[<a1361c16>] kernel_init_freeable+0xda/0x13c
[<a125b59d>] kernel_init+0x9/0xd0
[<a1004304>] ret_from_kernel_thread+0xc/0x18

Only free high memory pages that are not reserved.

Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/xtensa/mm/init.c | 70 +++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 63 insertions(+), 7 deletions(-)

--- a/arch/xtensa/mm/init.c
+++ b/arch/xtensa/mm/init.c
@@ -79,19 +79,75 @@ void __init zones_init(void)
free_area_init_node(0, zones_size, ARCH_PFN_OFFSET, NULL);
}

+#ifdef CONFIG_HIGHMEM
+static void __init free_area_high(unsigned long pfn, unsigned long end)
+{
+ for (; pfn < end; pfn++)
+ free_highmem_page(pfn_to_page(pfn));
+}
+
+static void __init free_highpages(void)
+{
+ unsigned long max_low = max_low_pfn;
+ struct memblock_region *mem, *res;
+
+ reset_all_zones_managed_pages();
+ /* set highmem page free */
+ for_each_memblock(memory, mem) {
+ unsigned long start = memblock_region_memory_base_pfn(mem);
+ unsigned long end = memblock_region_memory_end_pfn(mem);
+
+ /* Ignore complete lowmem entries */
+ if (end <= max_low)
+ continue;
+
+ if (memblock_is_nomap(mem))
+ continue;
+
+ /* Truncate partial highmem entries */
+ if (start < max_low)
+ start = max_low;
+
+ /* Find and exclude any reserved regions */
+ for_each_memblock(reserved, res) {
+ unsigned long res_start, res_end;
+
+ res_start = memblock_region_reserved_base_pfn(res);
+ res_end = memblock_region_reserved_end_pfn(res);
+
+ if (res_end < start)
+ continue;
+ if (res_start < start)
+ res_start = start;
+ if (res_start > end)
+ res_start = end;
+ if (res_end > end)
+ res_end = end;
+ if (res_start != start)
+ free_area_high(start, res_start);
+ start = res_end;
+ if (start == end)
+ break;
+ }
+
+ /* And now free anything which remains */
+ if (start < end)
+ free_area_high(start, end);
+ }
+}
+#else
+static void __init free_highpages(void)
+{
+}
+#endif
+
/*
* Initialize memory pages.
*/

void __init mem_init(void)
{
-#ifdef CONFIG_HIGHMEM
- unsigned long tmp;
-
- reset_all_zones_managed_pages();
- for (tmp = max_low_pfn; tmp < max_pfn; tmp++)
- free_highmem_page(pfn_to_page(tmp));
-#endif
+ free_highpages();

max_mapnr = max_pfn - ARCH_PFN_OFFSET;
high_memory = (void *)__va(max_low_pfn << PAGE_SHIFT);

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