diff options
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 37 |
1 files changed, 13 insertions, 24 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index f81149739eb9..3b6d20dfb9a8 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -909,8 +909,6 @@ static void cleanup_lazy_tlbs(struct mm_struct *mm) */ void __mmdrop(struct mm_struct *mm) { - int i; - BUG_ON(mm == &init_mm); WARN_ON_ONCE(mm == current->mm); @@ -925,9 +923,8 @@ void __mmdrop(struct mm_struct *mm) put_user_ns(mm->user_ns); mm_pasid_drop(mm); mm_destroy_cid(mm); + percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS); - for (i = 0; i < NR_MM_COUNTERS; i++) - percpu_counter_destroy(&mm->rss_stat[i]); free_mm(mm); } EXPORT_SYMBOL_GPL(__mmdrop); @@ -1260,8 +1257,6 @@ static void mm_init_uprobes_state(struct mm_struct *mm) static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, struct user_namespace *user_ns) { - int i; - mt_init_flags(&mm->mm_mt, MM_MT_FLAGS); mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock); atomic_set(&mm->mm_users, 1); @@ -1309,17 +1304,15 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, if (mm_alloc_cid(mm)) goto fail_cid; - for (i = 0; i < NR_MM_COUNTERS; i++) - if (percpu_counter_init(&mm->rss_stat[i], 0, GFP_KERNEL_ACCOUNT)) - goto fail_pcpu; + if (percpu_counter_init_many(mm->rss_stat, 0, GFP_KERNEL_ACCOUNT, + NR_MM_COUNTERS)) + goto fail_pcpu; mm->user_ns = get_user_ns(user_ns); lru_gen_init_mm(mm); return mm; fail_pcpu: - while (i > 0) - percpu_counter_destroy(&mm->rss_stat[--i]); mm_destroy_cid(mm); fail_cid: destroy_context(mm); @@ -1404,8 +1397,8 @@ EXPORT_SYMBOL_GPL(mmput_async); * This changes mm's executable file (shown as symlink /proc/[pid]/exe). * * Main users are mmput() and sys_execve(). Callers prevent concurrent - * invocations: in mmput() nobody alive left, in execve task is single - * threaded. + * invocations: in mmput() nobody alive left, in execve it happens before + * the new mm is made visible to anyone. * * Can only fail if new_exe_file != NULL. */ @@ -1440,9 +1433,7 @@ int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) /** * replace_mm_exe_file - replace a reference to the mm's executable file * - * This changes mm's executable file (shown as symlink /proc/[pid]/exe), - * dealing with concurrent invocation and without grabbing the mmap lock in - * write mode. + * This changes mm's executable file (shown as symlink /proc/[pid]/exe). * * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE). */ @@ -1472,22 +1463,20 @@ int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) return ret; } - /* set the new file, lockless */ ret = deny_write_access(new_exe_file); if (ret) return -EACCES; get_file(new_exe_file); - old_exe_file = xchg(&mm->exe_file, new_exe_file); + /* set the new file */ + mmap_write_lock(mm); + old_exe_file = rcu_dereference_raw(mm->exe_file); + rcu_assign_pointer(mm->exe_file, new_exe_file); + mmap_write_unlock(mm); + if (old_exe_file) { - /* - * Don't race with dup_mmap() getting the file and disallowing - * write access while someone might open the file writable. - */ - mmap_read_lock(mm); allow_write_access(old_exe_file); fput(old_exe_file); - mmap_read_unlock(mm); } return 0; } |