FAILED: patch "[PATCH] f2fs: don't use GFP_ZERO for page caches" failed to apply to 4.4-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 81114baa835b59ed02d14aa1d67f91ea874077cd Mon Sep 17 00:00:00 2001
From: Chao Yu <yuchao0@huawei.com>
Date: Mon, 9 Apr 2018 20:25:06 +0800
Subject: [PATCH] f2fs: don't use GFP_ZERO for page caches

Related to https://lkml.org/lkml/2018/4/8/661

Sometimes, we need to write meta data to new allocated block address,
then we will allocate a zeroed page in inner inode's address space, and
fill partial data in it, and leave other place with zero value which means
some fields are initial status.

There are two inner inodes (meta inode and node inode) setting __GFP_ZERO,
I have just checked them, for both of them, we can avoid using __GFP_ZERO,
and do initialization by ourselves to avoid unneeded/redundant zeroing
from mm.

Cc: <stable@vger.kernel.org>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 3d3a1f6b21a1..8fc55d42ba25 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -100,8 +100,10 @@ repeat:
 	 * readonly and make sure do not write checkpoint with non-uptodate
 	 * meta page.
 	 */
-	if (unlikely(!PageUptodate(page)))
+	if (unlikely(!PageUptodate(page))) {
+		memset(page_address(page), 0, PAGE_SIZE);
 		f2fs_stop_checkpoint(sbi, false);
+	}
 out:
 	return page;
 }
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 417c9dcd0269..87535bf63421 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -320,10 +320,10 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
 make_now:
 	if (ino == F2FS_NODE_INO(sbi)) {
 		inode->i_mapping->a_ops = &f2fs_node_aops;
-		mapping_set_gfp_mask(inode->i_mapping, GFP_F2FS_ZERO);
+		mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
 	} else if (ino == F2FS_META_INO(sbi)) {
 		inode->i_mapping->a_ops = &f2fs_meta_aops;
-		mapping_set_gfp_mask(inode->i_mapping, GFP_F2FS_ZERO);
+		mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
 	} else if (S_ISREG(inode->i_mode)) {
 		inode->i_op = &f2fs_file_inode_operations;
 		inode->i_fop = &f2fs_file_operations;
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index a7ec952093f8..0fb006f591a4 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1979,6 +1979,7 @@ static void write_current_sum_page(struct f2fs_sb_info *sbi,
 	struct f2fs_summary_block *dst;
 
 	dst = (struct f2fs_summary_block *)page_address(page);
+	memset(dst, 0, PAGE_SIZE);
 
 	mutex_lock(&curseg->curseg_mutex);
 
@@ -3133,6 +3134,7 @@ static void write_compacted_summaries(struct f2fs_sb_info *sbi, block_t blkaddr)
 
 	page = grab_meta_page(sbi, blkaddr++);
 	kaddr = (unsigned char *)page_address(page);
+	memset(kaddr, 0, PAGE_SIZE);
 
 	/* Step 1: write nat cache */
 	seg_i = CURSEG_I(sbi, CURSEG_HOT_DATA);
@@ -3157,6 +3159,7 @@ static void write_compacted_summaries(struct f2fs_sb_info *sbi, block_t blkaddr)
 			if (!page) {
 				page = grab_meta_page(sbi, blkaddr++);
 				kaddr = (unsigned char *)page_address(page);
+				memset(kaddr, 0, PAGE_SIZE);
 				written_size = 0;
 			}
 			summary = (struct f2fs_summary *)(kaddr + written_size);
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 3325d0769723..492ad0c86fa9 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -375,6 +375,7 @@ static inline void seg_info_to_sit_page(struct f2fs_sb_info *sbi,
 	int i;
 
 	raw_sit = (struct f2fs_sit_block *)page_address(page);
+	memset(raw_sit, 0, PAGE_SIZE);
 	for (i = 0; i < end - start; i++) {
 		rs = &raw_sit->entries[i];
 		se = get_seg_entry(sbi, start + i);