Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull sysctl fix from Eric Biederman:
"A rather embarassing and hard to hit bug was merged into 4.11-rc1.
Andrei Vagin tracked this bug now and after some staring at the code
I came up with a fix"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
proc: Fix proc_sys_prune_dcache to hold a sb reference
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index c5ae09b..1869459 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -67,7 +67,7 @@ struct proc_inode {
struct proc_dir_entry *pde;
struct ctl_table_header *sysctl;
struct ctl_table *sysctl_entry;
- struct list_head sysctl_inodes;
+ struct hlist_node sysctl_inodes;
const struct proc_ns_operations *ns_ops;
struct inode vfs_inode;
};
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 67985a7..9bf06e2 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -191,7 +191,7 @@ static void init_header(struct ctl_table_header *head,
head->set = set;
head->parent = NULL;
head->node = node;
- INIT_LIST_HEAD(&head->inodes);
+ INIT_HLIST_HEAD(&head->inodes);
if (node) {
struct ctl_table *entry;
for (entry = table; entry->procname; entry++, node++)
@@ -261,25 +261,42 @@ static void unuse_table(struct ctl_table_header *p)
complete(p->unregistering);
}
-/* called under sysctl_lock */
static void proc_sys_prune_dcache(struct ctl_table_header *head)
{
- struct inode *inode, *prev = NULL;
+ struct inode *inode;
struct proc_inode *ei;
+ struct hlist_node *node;
+ struct super_block *sb;
rcu_read_lock();
- list_for_each_entry_rcu(ei, &head->inodes, sysctl_inodes) {
- inode = igrab(&ei->vfs_inode);
- if (inode) {
- rcu_read_unlock();
- iput(prev);
- prev = inode;
- d_prune_aliases(inode);
+ for (;;) {
+ node = hlist_first_rcu(&head->inodes);
+ if (!node)
+ break;
+ ei = hlist_entry(node, struct proc_inode, sysctl_inodes);
+ spin_lock(&sysctl_lock);
+ hlist_del_init_rcu(&ei->sysctl_inodes);
+ spin_unlock(&sysctl_lock);
+
+ inode = &ei->vfs_inode;
+ sb = inode->i_sb;
+ if (!atomic_inc_not_zero(&sb->s_active))
+ continue;
+ inode = igrab(inode);
+ rcu_read_unlock();
+ if (unlikely(!inode)) {
+ deactivate_super(sb);
rcu_read_lock();
+ continue;
}
+
+ d_prune_aliases(inode);
+ iput(inode);
+ deactivate_super(sb);
+
+ rcu_read_lock();
}
rcu_read_unlock();
- iput(prev);
}
/* called under sysctl_lock, will reacquire if has to wait */
@@ -461,7 +478,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb,
}
ei->sysctl = head;
ei->sysctl_entry = table;
- list_add_rcu(&ei->sysctl_inodes, &head->inodes);
+ hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes);
head->count++;
spin_unlock(&sysctl_lock);
@@ -489,7 +506,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb,
void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
{
spin_lock(&sysctl_lock);
- list_del_rcu(&PROC_I(inode)->sysctl_inodes);
+ hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes);
if (!--head->count)
kfree_rcu(head, rcu);
spin_unlock(&sysctl_lock);
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 80d0781..1c04a26 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -143,7 +143,7 @@ struct ctl_table_header
struct ctl_table_set *set;
struct ctl_dir *parent;
struct ctl_node *node;
- struct list_head inodes; /* head for proc_inode->sysctl_inodes */
+ struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
};
struct ctl_dir {