Skip to contentSkip to conversation

Patch "don't put symlink bodies in pagecache into highmem" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Feb 7, 2018

Subsystems (4)
Stable branch VFS ext4 file system F2FS file system
lore
Share & tools
lore

[email protected]

author maintainer Applied
#0 lore raw

This is a note to let you know that I've just added the patch titled

don't put symlink bodies in pagecache into highmem

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
don-t-put-symlink-bodies-in-pagecache-into-highmem.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 21fc61c73c3903c4c312d0802da01ec2b323d174 Mon Sep 17 00:00:00 2001

From: Al Viro <[email protected]>
Date: Tue, 17 Nov 2015 01:07:57 -0500
Subject: don't put symlink bodies in pagecache into highmem

From: Al Viro <[email protected]>

commit 21fc61c73c3903c4c312d0802da01ec2b323d174 upstream.

kmap() in page_follow_link_light() needed to go - allowing to hold an arbitrary number of kmaps for long is a great way to deadlocking the system.

new helper (inode_nohighmem(inode)) needs to be used for pagecache symlinks inodes; done for all in-tree cases. page_follow_link_light() instrumented to yell about anything missed.

Signed-off-by Al Viro <[email protected]>
Signed-off-by Jin Qian <[email protected]>
Signed-off-by Jin Qian <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 fs/ext4/inode.c    |    1 +
 fs/ext4/namei.c    |    1 +
 fs/ext4/symlink.c  |   10 +++-------
 fs/f2fs/inode.c    |    1 +
 fs/f2fs/namei.c    |    5 ++---
 fs/inode.c         |    6 ++++++
 include/linux/fs.h |    1 +
 7 files changed, 15 insertions(+), 10 deletions(-)
fs/ext4/inode.c +1 -0
@@ -4417,6 +4417,7 @@ struct inode *ext4_iget(struct super_blo
 			inode->i_op = &ext4_symlink_inode_operations;
 			ext4_set_aops(inode);
 		}
+		inode_nohighmem(inode);
 	} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
 	      S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 		inode->i_op = &ext4_special_inode_operations;
fs/ext4/namei.c +1 -0
@@ -3151,6 +3151,7 @@ static int ext4_symlink(struct inode *di
 	if ((disk_link.len > EXT4_N_BLOCKS * 4)) {
 		if (!encryption_required)
 			inode->i_op = &ext4_symlink_inode_operations;
+		inode_nohighmem(inode);
 		ext4_set_aops(inode);
 		/*
 		 * We cannot call page_symlink() with transaction started
fs/ext4/symlink.c +3 -7
@@ -45,7 +45,7 @@ static const char *ext4_encrypted_follow
 		cpage = read_mapping_page(inode->i_mapping, 0, NULL);
 		if (IS_ERR(cpage))
 			return ERR_CAST(cpage);
-		caddr = kmap(cpage);
+		caddr = page_address(cpage);
 		caddr[size] = 0;
 	}
 

@@ -75,16 +75,12 @@ static const char *ext4_encrypted_follow
 	/* Null-terminate the name */
 	if (res <= plen)
 		paddr[res] = '\0';
-	if (cpage) {
-		kunmap(cpage);
+	if (cpage)
 		page_cache_release(cpage);
-	}
 	return *cookie = paddr;
 errout:
-	if (cpage) {
-		kunmap(cpage);
+	if (cpage)
 		page_cache_release(cpage);
-	}
 	kfree(paddr);
 	return ERR_PTR(res);
 }
fs/f2fs/inode.c +1 -0
@@ -202,6 +202,7 @@ make_now:
 			inode->i_op = &f2fs_encrypted_symlink_inode_operations;
 		else
 			inode->i_op = &f2fs_symlink_inode_operations;
+		inode_nohighmem(inode);
 		inode->i_mapping->a_ops = &f2fs_dblock_aops;
 	} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
 			S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
fs/f2fs/namei.c +2 -3
@@ -351,6 +351,7 @@ static int f2fs_symlink(struct inode *di
 		inode->i_op = &f2fs_encrypted_symlink_inode_operations;
 	else
 		inode->i_op = &f2fs_symlink_inode_operations;
+	inode_nohighmem(inode);
 	inode->i_mapping->a_ops = &f2fs_dblock_aops;
 
 	f2fs_lock_op(sbi);

@@ -942,7 +943,7 @@ static const char *f2fs_encrypted_follow
 	cpage = read_mapping_page(inode->i_mapping, 0, NULL);
 	if (IS_ERR(cpage))
 		return ERR_CAST(cpage);
-	caddr = kmap(cpage);
+	caddr = page_address(cpage);
 	caddr[size] = 0;
 
 	/* Symlink is encrypted */

@@ -982,13 +983,11 @@ static const char *f2fs_encrypted_follow
 	/* Null-terminate the name */
 	paddr[res] = '\0';
 
-	kunmap(cpage);
 	page_cache_release(cpage);
 	return *cookie = paddr;
 errout:
 	kfree(cstr.name);
 	f2fs_fname_crypto_free_buffer(&pstr);
-	kunmap(cpage);
 	page_cache_release(cpage);
 	return ERR_PTR(res);
 }
fs/inode.c +6 -0
@@ -2028,3 +2028,9 @@ void inode_set_flags(struct inode *inode
 				  new_flags) != old_flags));
 }
 EXPORT_SYMBOL(inode_set_flags);
+
+void inode_nohighmem(struct inode *inode)
+{
+	mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
+}
+EXPORT_SYMBOL(inode_nohighmem);
include/linux/fs.h +1 -0
@@ -3066,5 +3066,6 @@ static inline bool dir_relax(struct inod
 }
 
 extern bool path_noexec(const struct path *path);
+extern void inode_nohighmem(struct inode *inode);
 
 #endif /* _LINUX_FS_H */

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/don-t-put-symlink-bodies-in-pagecache-into-highmem.patch