Commit 612fe2d2 authored by Mike Rapoport's avatar Mike Rapoport Committed by Zheng Zengkai
Browse files

mm: fix initialization of struct page for holes in memory layout 

stable inclusion
from stable-5.10.11
commit f2a79851c776a5345643e0234957f98528ada168
bugzilla: 47621

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

commit d3921cb8 upstream.

There could be struct pages that are not backed by actual physical
memory.  This can happen when the actual memory bank is not a multiple
of SECTION_SIZE or when an architecture does not register memory holes
reserved by the firmware as memblock.memory.

Such pages are currently initialized using init_unavailable_mem()
function that iterates through PFNs in holes in memblock.memory and if
there is a struct page corresponding to a PFN, the fields if this page
are set to default values and the page is marked as Reserved.

init_unavailable_mem() does not take into account zone and node the page
belongs to and sets both zone and node links in struct page to zero.

On a system that has firmware reserved holes in a zone above ZONE_DMA,
for instance in a configuration below:

	# grep -A1 E820 /proc/iomem
	7a17b000-7a216fff : Unknown E820 type
	7a217000-7bffffff : System RAM

unset zone link in struct page will trigger

	VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);

because there are pages in both ZONE_DMA32 and ZONE_DMA (unset zone link
in struct page) in the same pageblock.

Update init_unavailable_mem() to use zone constraints defined by an
architecture to properly setup the zone link and use node ID of the
adjacent range in memblock.memory to set the node link.

Link: https://lkml.kernel.org/r/20210111194017.22696-3-rppt@kernel.org


Fixes: 73a6e474 ("mm: memmap_init: iterate over memblock regions rather that check each PFN")
Signed-off-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Reported-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
parent d534b825

mm/page_alloc.c

+50 −34
Original line number Diff line number Diff line
@@ -7001,23 +7001,26 @@ void __init free_area_init_memoryless_node(int nid) 
 * Initialize all valid struct pages in the range [spfn, epfn) and mark them

 * PageReserved(). Return the number of struct pages that were initialized.

 */

static u64 __init init_unavailable_range(unsigned long spfn, unsigned long epfn)

static u64 __init init_unavailable_range(unsigned long spfn, unsigned long epfn,

					 int zone, int nid)

{

	unsigned long pfn;

	unsigned long pfn, zone_spfn, zone_epfn;

	u64 pgcnt = 0;



	zone_spfn = arch_zone_lowest_possible_pfn[zone];

	zone_epfn = arch_zone_highest_possible_pfn[zone];



	spfn = clamp(spfn, zone_spfn, zone_epfn);

	epfn = clamp(epfn, zone_spfn, zone_epfn);



	for (pfn = spfn; pfn < epfn; pfn++) {

		if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) {

			pfn = ALIGN_DOWN(pfn, pageblock_nr_pages)

				+ pageblock_nr_pages - 1;

			continue;

		}

		/*

		 * Use a fake node/zone (0) for now. Some of these pages

		 * (in memblock.reserved but not in memblock.memory) will

		 * get re-initialized via reserve_bootmem_region() later.

		 */

		__init_single_page(pfn_to_page(pfn), pfn, 0, 0);



		__init_single_page(pfn_to_page(pfn), pfn, zone, nid);

		__SetPageReserved(pfn_to_page(pfn));

		pgcnt++;

	}
@@ -7026,51 +7029,64 @@ static u64 __init init_unavailable_range(unsigned long spfn, unsigned long epfn) 
}



/*

 * Only struct pages that are backed by physical memory are zeroed and

 * initialized by going through __init_single_page(). But, there are some

 * struct pages which are reserved in memblock allocator and their fields

 * may be accessed (for example page_to_pfn() on some configuration accesses

 * flags). We must explicitly initialize those struct pages.

 * Only struct pages that correspond to ranges defined by memblock.memory

 * are zeroed and initialized by going through __init_single_page() during

 * memmap_init().

 *

 * This function also addresses a similar issue where struct pages are left

 * uninitialized because the physical address range is not covered by

 * memblock.memory or memblock.reserved. That could happen when memblock

 * layout is manually configured via memmap=, or when the highest physical

 * address (max_pfn) does not end on a section boundary.

 * But, there could be struct pages that correspond to holes in

 * memblock.memory. This can happen because of the following reasons:

 * - phyiscal memory bank size is not necessarily the exact multiple of the

 *   arbitrary section size

 * - early reserved memory may not be listed in memblock.memory

 * - memory layouts defined with memmap= kernel parameter may not align

 *   nicely with memmap sections

 *

 * Explicitly initialize those struct pages so that:

 * - PG_Reserved is set

 * - zone link is set accorging to the architecture constrains

 * - node is set to node id of the next populated region except for the

 *   trailing hole where last node id is used

 */

static void __init init_unavailable_mem(void)

static void __init init_zone_unavailable_mem(int zone)

{

	phys_addr_t start, end;

	u64 i, pgcnt;

	phys_addr_t next = 0;

	unsigned long start, end;

	int i, nid;

	u64 pgcnt;

	unsigned long next = 0;



	/*

	 * Loop through unavailable ranges not covered by memblock.memory.

	 * Loop through holes in memblock.memory and initialize struct

	 * pages corresponding to these holes

	 */

	pgcnt = 0;

	for_each_mem_range(i, &start, &end) {

	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid) {

		if (next < start)

			pgcnt += init_unavailable_range(PFN_DOWN(next),

							PFN_UP(start));

			pgcnt += init_unavailable_range(next, start, zone, nid);

		next = end;

	}



	/*

	 * Early sections always have a fully populated memmap for the whole

	 * section - see pfn_valid(). If the last section has holes at the

	 * end and that section is marked "online", the memmap will be

	 * considered initialized. Make sure that memmap has a well defined

	 * state.

	 * Last section may surpass the actual end of memory (e.g. we can

	 * have 1Gb section and 512Mb of RAM pouplated).

	 * Make sure that memmap has a well defined state in this case.

	 */

	pgcnt += init_unavailable_range(PFN_DOWN(next),

					round_up(max_pfn, PAGES_PER_SECTION));

	end = round_up(max_pfn, PAGES_PER_SECTION);

	pgcnt += init_unavailable_range(next, end, zone, nid);



	/*

	 * Struct pages that do not have backing memory. This could be because

	 * firmware is using some of this memory, or for some other reasons.

	 */

	if (pgcnt)

		pr_info("Zeroed struct page in unavailable ranges: %lld pages", pgcnt);

		pr_info("Zone %s: zeroed struct page in unavailable ranges: %lld pages", zone_names[zone], pgcnt);

}



static void __init init_unavailable_mem(void)

{

	int zone;



	for (zone = 0; zone < ZONE_MOVABLE; zone++)

		init_zone_unavailable_mem(zone);

}

#else

static inline void __init init_unavailable_mem(void)