On 2013/1/25 15:26, Al Viro wrpte: > On Fri, Jan 25, 2013 at 03:09:48PM +0800, Li Zefan wrote: >> rename() will change dentry->d_name. The result of this race can >> be worse than seeing partially rewritten name, but we might access >> a stale pointer because rename() will re-allocate memory to hold >> a longer name. >> >> It's safe in the protection of dentry->d_lock. >> >> Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx> >> --- >> kernel/cpuset.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/kernel/cpuset.c b/kernel/cpuset.c >> index 16be7c9..b2476c2 100644 >> --- a/kernel/cpuset.c >> +++ b/kernel/cpuset.c >> @@ -2606,8 +2606,12 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk) >> >> dentry = task_cs(tsk)->css.cgroup->dentry; >> spin_lock(&cpuset_buffer_lock); >> + >> + spin_lock(&dentry->d_lock); >> snprintf(cpuset_name, CPUSET_NAME_LEN, >> dentry ? (const char *)dentry->d_name.name : "/"); > > Ahem... Can dentry actually be NULL here? If not, this conditional > is bogus; otherwise, spin_lock(&dentry->d_lock) is going to blow up... oops, my fault...It's NULL if cpuset is not mounted. -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
