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 <stable@xxxxxxxxxxxxxxx> know about it.
>From 21fc61c73c3903c4c312d0802da01ec2b323d174 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue, 17 Nov 2015 01:07:57 -0500
Subject: don't put symlink bodies in pagecache into highmem
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
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 <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jin Qian <jinqian@xxxxxxxxxx>
Signed-off-by: Jin Qian <jinqian@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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(-)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -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;
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -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
--- a/fs/ext4/symlink.c
+++ b/fs/ext4/symlink.c
@@ -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);
}
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -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)) {
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -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);
}
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -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);
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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 viro@xxxxxxxxxxxxxxxxxx are
queue-4.4/don-t-put-symlink-bodies-in-pagecache-into-highmem.patch