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Commit 6ac5a11d authored by Max Filippov's avatar Max Filippov
Browse files

xtensa: fix high memory/reserved memory collision 



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: default avatarMax Filippov <jcmvbkbc@gmail.com>
parent 7928b2cb

arch/xtensa/mm/init.c

+63 −7
Original line number Diff line number Diff line
@@ -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);