diff options
| -rw-r--r-- | kernel/sys.c | 11 | ||||
| -rw-r--r-- | mm/util.c | 4 |
2 files changed, 11 insertions, 4 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index 775bf8d18d03..2969304c29fe 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2127,9 +2127,15 @@ static int prctl_set_mm(int opt, unsigned long addr, error = -EINVAL; - down_write(&mm->mmap_sem); + /* + * arg_lock protects concurent updates of arg boundaries, we need + * mmap_sem for a) concurrent sys_brk, b) finding VMA for addr + * validation. + */ + down_read(&mm->mmap_sem); vma = find_vma(mm, addr); + spin_lock(&mm->arg_lock); prctl_map.start_code = mm->start_code; prctl_map.end_code = mm->end_code; prctl_map.start_data = mm->start_data; @@ -2217,7 +2223,8 @@ static int prctl_set_mm(int opt, unsigned long addr, error = 0; out: - up_write(&mm->mmap_sem); + spin_unlock(&mm->arg_lock); + up_read(&mm->mmap_sem); return error; } diff --git a/mm/util.c b/mm/util.c index 91682a2090ee..9834c4ab7d8e 100644 --- a/mm/util.c +++ b/mm/util.c @@ -718,12 +718,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) if (!mm->arg_end) goto out_mm; /* Shh! No looking before we're done */ - down_read(&mm->mmap_sem); + spin_lock(&mm->arg_lock); arg_start = mm->arg_start; arg_end = mm->arg_end; env_start = mm->env_start; env_end = mm->env_end; - up_read(&mm->mmap_sem); + spin_unlock(&mm->arg_lock); len = arg_end - arg_start; |