alpha: register early reserved memory in memblock

The memory reserved by console/PALcode or non-volatile memory is not added
to memblock.memory.

Since commit fa3354e (mm: free_area_init: use maximal zone PFNs rather
than zone sizes) the initialization of the memory map relies on the
accuracy of memblock.memory to properly calculate zone sizes. The holes in
memblock.memory caused by absent regions reserved by the firmware cause
incorrect initialization of struct pages which leads to BUG() during the
initial page freeing:

BUG: Bad page state in process swapper  pfn:2ffc53
page:fffffc000ecf14c0 refcount:0 mapcount:1 mapping:0000000000000000 index:0x0
flags: 0x0()
raw: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
raw: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
page dumped because: nonzero mapcount
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 5.7.0-03841-gfa3354e4ea39-dirty Rust-for-Linux#26
       fffffc0001b5bd68 fffffc0001b5be80 fffffc00011cd148 fffffc000ecf14c0
       fffffc00019803df fffffc0001b5be80 fffffc00011ce340 fffffc000ecf14c0
       0000000000000000 fffffc0001b5be80 fffffc0001b482c0 fffffc00027d6618
       fffffc00027da7d0 00000000002ff97a 0000000000000000 fffffc0001b5be80
       fffffc00011d1abc fffffc000ecf14c0 fffffc0002d00000 fffffc0001b5be80
       fffffc0001b2350c 0000000000300000 fffffc0001b48298 fffffc0001b482c0
Trace:
[<fffffc00011cd148>] bad_page+0x168/0x1b0
[<fffffc00011ce340>] free_pcp_prepare+0x1e0/0x290
[<fffffc00011d1abc>] free_unref_page+0x2c/0xa0
[<fffffc00014ee5f0>] cmp_ex_sort+0x0/0x30
[<fffffc00014ee5f0>] cmp_ex_sort+0x0/0x30
[<fffffc000101001c>] _stext+0x1c/0x20

Fix this by registering the reserved ranges in memblock.memory.

Link: https://lore.kernel.org/lkml/20210726192311.uffqnanxw3ac5wwi@ivybridge
Fixes: fa3354e ("mm: free_area_init: use maximal zone PFNs rather than zone sizes")
Reported-by: Matt Turner <[email protected]>
Cc: <[email protected]>
Signed-off-by: Mike Rapoport <[email protected]>
Signed-off-by: Matt Turner <[email protected]>

Author: rppt

arch/alpha/kernel/setup.c

@@ -319,18 +319,19 @@ setup_memory(void *kernel_end)
 		       i, cluster->usage, cluster->start_pfn,
 		       cluster->start_pfn + cluster->numpages);
 
-		/* Bit 0 is console/PALcode reserved.  Bit 1 is
-		   non-volatile memory -- we might want to mark
-		   this for later.  */
-		if (cluster->usage & 3)
-			continue;
-
 		end = cluster->start_pfn + cluster->numpages;
 		if (end > max_low_pfn)
 			max_low_pfn = end;
 
 		memblock_add(PFN_PHYS(cluster->start_pfn),
 			     cluster->numpages << PAGE_SHIFT);
+
+		/* Bit 0 is console/PALcode reserved.  Bit 1 is
+		   non-volatile memory -- we might want to mark
+		   this for later.  */
+		if (cluster->usage & 3)
+			memblock_reserve(PFN_PHYS(cluster->start_pfn),
+				         cluster->numpages << PAGE_SHIFT);
 	}
 
 	/*