PM: hibernate: Complain about memory map mismatches during resume

The system memory map can change over a hibernation-restore cycle due
to a defect in the platform firmware, and some of the page frames used
by the kernel before hibernation may not be available any more during
the subsequent restore which leads to the error below.

[  T357] PM: Image loading progress:   0%
[  T357] PM: Read 2681596 kbytes in 0.03 seconds (89386.53 MB/s)
[  T357] PM: Error -14 resuming
[  T357] PM: Failed to load hibernation image, recovering.
[  T357] PM: Basic memory bitmaps freed
[  T357] OOM killer enabled.
[  T357] Restarting tasks ... done.
[  T357] PM: resume from hibernation failed (-14)
[  T357] PM: Hibernation image not present or could not be loaded.

Add an error message to the unpack() function to allow problematic
page frames to be identified and the source of the problem to be
diagnosed more easily. This can save developers quite a bit of
debugging time.

Signed-off-by: Xueqin Luo <luoxueqin@kylinos.cn>
[ rjw: New subject, edited changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: Xueqin Luo

kernel/power/snapshot.c

@@ -2259,10 +2259,14 @@ static int unpack_orig_pfns(unsigned long *buf, struct memory_bitmap *bm)
 		if (unlikely(buf[j] == BM_END_OF_MAP))
 			break;
 
-		if (pfn_valid(buf[j]) && memory_bm_pfn_present(bm, buf[j]))
+		if (pfn_valid(buf[j]) && memory_bm_pfn_present(bm, buf[j])) {
 			memory_bm_set_bit(bm, buf[j]);
-		else
+		} else {
+			if (!pfn_valid(buf[j]))
+				pr_err(FW_BUG "Memory map mismatch at 0x%llx after hibernation\n",
+				       (unsigned long long)PFN_PHYS(buf[j]));
 			return -EFAULT;
+		}
 	}
 
 	return 0;