Revert "mm: page_alloc: skip over regions of invalid pfns where possible"

This reverts b92df1de5d289c0b ("mm: page_alloc: skip over regions of
invalid pfns where possible").  The commit is meant to be a boot init
speed up skipping the loop in memmap_init_zone() for invalid pfns.  But
given some specific memory mapping on x86_64 (or more generally
theoretically anywhere but on arm with CONFIG_HAVE_ARCH_PFN_VALID) the
implementation also skips valid pfns which is plain wrong and causes
'kernel BUG at mm/page_alloc.c:1389!'

crash> log | grep -e BUG -e RIP -e Call.Trace -e move_freepages_block -e rmqueue -e freelist -A1
kernel BUG at mm/page_alloc.c:1389!
invalid opcode: 0000 [#1] SMP
--
RIP: 0010:[<ffffffff8118833e>]  [<ffffffff8118833e>] move_freepages+0x15e/0x160
RSP: 0018:ffff88054d727688  EFLAGS: 00010087
--
Call Trace:
 [<ffffffff811883b3>] move_freepages_block+0x73/0x80
 [<ffffffff81189e63>] __rmqueue+0x263/0x460
 [<ffffffff8118c781>] get_page_from_freelist+0x7e1/0x9e0
 [<ffffffff8118caf6>] __alloc_pages_nodemask+0x176/0x420
--
RIP  [<ffffffff8118833e>] move_freepages+0x15e/0x160
 RSP <ffff88054d727688>

crash> page_init_bug -v | grep RAM
<struct resource 0xffff88067fffd2f8>          1000 -        9bfff       System RAM (620.00 KiB)
<struct resource 0xffff88067fffd3a0>        100000 -     430bffff       System RAM (  1.05 GiB = 1071.75 MiB = 1097472.00 KiB)
<struct resource 0xffff88067fffd410>      4b0c8000 -     4bf9cfff       System RAM ( 14.83 MiB = 15188.00 KiB)
<struct resource 0xffff88067fffd480>      4bfac000 -     646b1fff       System RAM (391.02 MiB = 400408.00 KiB)
<struct resource 0xffff88067fffd560>      7b788000 -     7b7fffff       System RAM (480.00 KiB)
<struct resource 0xffff88067fffd640>     100000000 -    67fffffff       System RAM ( 22.00 GiB)

crash> page_init_bug | head -6
<struct resource 0xffff88067fffd560>      7b788000 -     7b7fffff       System RAM (480.00 KiB)
<struct page 0xffffea0001ede200>   1fffff00000000  0 <struct pglist_data 0xffff88047ffd9000> 1 <struct zone 0xffff88047ffd9800> DMA32          4096    1048575
<struct page 0xffffea0001ede200> 505736 505344 <struct page 0xffffea0001ed8000> 505855 <struct page 0xffffea0001edffc0>
<struct page 0xffffea0001ed8000>                0  0 <struct pglist_data 0xffff88047ffd9000> 0 <struct zone 0xffff88047ffd9000> DMA               1       4095
<struct page 0xffffea0001edffc0>   1fffff00000400  0 <struct pglist_data 0xffff88047ffd9000> 1 <struct zone 0xffff88047ffd9800> DMA32          4096    1048575
BUG, zones differ!

crash> kmem -p 77fff000 78000000 7b5ff000 7b600000 7b787000 7b788000
      PAGE        PHYSICAL      MAPPING       INDEX CNT FLAGS
ffffea0001e00000  78000000                0        0  0 0
ffffea0001ed7fc0  7b5ff000                0        0  0 0
ffffea0001ed8000  7b600000                0        0  0 0       <<<<
ffffea0001ede1c0  7b787000                0        0  0 0
ffffea0001ede200  7b788000                0        0  1 1fffff00000000

Link: http://lkml.kernel.org/r/20180316143855.29838-1-neelx@redhat.com
Fixes: b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns where possible")
Signed-off-by: Daniel Vacek <neelx@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <>

3 files changed, 1 insertions, 40 deletions

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index c2f1a6996fad..0257aee7ab4b 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -203,8 +203,6 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
 	     i >= 0; __next_mem_pfn_range(&i, nid, p_start, p_end, p_nid))
 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
 
-unsigned long memblock_next_valid_pfn(unsigned long pfn, unsigned long max_pfn);
-
 /**
  * for_each_free_mem_range - iterate through free memblock areas
  * @i: u64 used as loop variable
diff --git a/mm/memblock.c b/mm/memblock.c
index 4b21bad80214..1b59a37f5390 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1133,34 +1133,6 @@ int __init_memblock memblock_set_node(phys_addr_t base, phys_addr_t size,
 }
 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
 
-unsigned long __init_memblock memblock_next_valid_pfn(unsigned long pfn,
-						      unsigned long max_pfn)
-{
-	struct memblock_type *type = &memblock.memory;
-	unsigned int right = type->cnt;
-	unsigned int mid, left = 0;
-	phys_addr_t addr = PFN_PHYS(pfn + 1);
-
-	do {
-		mid = (right + left) / 2;
-
-		if (addr < type->regions[mid].base)
-			right = mid;
-		else if (addr >= (type->regions[mid].base +
-				  type->regions[mid].size))
-			left = mid + 1;
-		else {
-			/* addr is within the region, so pfn + 1 is valid */
-			return min(pfn + 1, max_pfn);
-		}
-	} while (left < right);
-
-	if (right == type->cnt)
-		return max_pfn;
-	else
-		return min(PHYS_PFN(type->regions[right].base), max_pfn);
-}
-
 static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
 					phys_addr_t align, phys_addr_t start,
 					phys_addr_t end, int nid, ulong flags)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a1966e1bb080..1918f5233beb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5480,17 +5480,8 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 		if (context != MEMMAP_EARLY)
 			goto not_early;
 
-		if (!early_pfn_valid(pfn)) {
-#ifdef CONFIG_HAVE_MEMBLOCK
-			/*
-			 * Skip to the pfn preceding the next valid one (or
-			 * end_pfn), such that we hit a valid pfn (or end_pfn)
-			 * on our next iteration of the loop.
-			 */
-			pfn = memblock_next_valid_pfn(pfn, end_pfn) - 1;
-#endif
+		if (!early_pfn_valid(pfn))
 			continue;
-		}
 		if (!early_pfn_in_nid(pfn, nid))
 			continue;
 		if (!update_defer_init(pgdat, pfn, end_pfn, &nr_initialised))