The proc_inode_is_dead function might race with __unhash_process.
This will result in a whole bunch of stale proc entries being cached.
To prevent that, add the required locking.
Signed-off-by: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Christian Brauner <christian@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
---
fs/proc/base.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 1bc9bcd..59720bc 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1994,7 +1994,13 @@ static int pid_revalidate(struct dentry *dentry, unsigned int flags)
static inline bool proc_inode_is_dead(struct inode *inode)
{
- return !proc_pid(inode)->tasks[PIDTYPE_PID].first;
+ bool has_task;
+
+ read_lock(&tasklist_lock);
+ has_task = pid_has_task(proc_pid(inode), PIDTYPE_PID);
+ read_unlock(&tasklist_lock);
+
+ return !has_task;
}
int pid_delete_dentry(const struct dentry *dentry)
--
1.8.3.1
