[PATCH -next 2/2] PM: hibernate: add check of preallocate mem for image size pages

[TGSP <tgsp002@gmail.com>]

From: xiongxin <xiongxin@kylinos.cn>

Added a check on the return value of preallocate_image_highmem(). If
memory preallocate is insufficient, S4 cannot be done;

I am playing 4K video on a machine with AMD or other graphics card and
only 8GiB memory, and the kernel is not configured with CONFIG_HIGHMEM.
When doing the S4 test, the analysis found that when the pages get from
minimum_image_size() is large enough, The preallocate_image_memory() and
preallocate_image_highmem() calls failed to obtain enough memory. Add
the judgment that memory preallocate is insufficient;

"pages -= free_unnecessary_pages()" below will let pages to drop a lot,
so I wonder if it makes sense to add a judgment here.

Cc: stable@vger.kernel.org
Signed-off-by: xiongxin <xiongxin@kylinos.cn>
Signed-off-by: huanglei <huanglei@kylinos.cn>
---
 kernel/power/snapshot.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index c20ca5fb9adc..670abf89cf31 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1738,6 +1738,7 @@ int hibernate_preallocate_memory(void)
 	struct zone *zone;
 	unsigned long saveable, size, max_size, count, highmem, pages = 0;
 	unsigned long alloc, save_highmem, pages_highmem, avail_normal;
+	unsigned long size_highmem;
 	ktime_t start, stop;
 	int error;
 
@@ -1863,7 +1864,13 @@ int hibernate_preallocate_memory(void)
 		pages_highmem += size;
 		alloc -= size;
 		size = preallocate_image_memory(alloc, avail_normal);
-		pages_highmem += preallocate_image_highmem(alloc - size);
+		size_highmem += preallocate_image_highmem(alloc - size);
+		if (size_highmem < (alloc - size)) {
+			pr_err("Image allocation is %lu pages short, exit\n",
+				alloc - size - pages_highmem);
+			goto err_out;
+		}
+		pages_highmem += size_highmem;
 		pages += pages_highmem + size;
 	}
 
-- 
2.25.1