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authorDavid Rientjes <rientjes@google.com>2010-10-26 17:21:26 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-26 19:52:05 -0400
commitd19d5476f4b9f91d2de92b91588bb118beba6c0d (patch)
treeb267c225c2b7507f7e4900676649b20e56e06ba2 /fs/proc
parent723548bff1dde9ab6bdb23f4bb92277c4da49473 (diff)
oom: fix locking for oom_adj and oom_score_adj
The locking order in oom_adjust_write() and oom_score_adj_write() for task->alloc_lock and task->sighand->siglock is reversed, and lockdep notices that irqs could encounter an ABBA scenario. This fixes the locking order so that we always take task_lock(task) prior to lock_task_sighand(task). Signed-off-by: David Rientjes <rientjes@google.com> Reported-by: Andrew Morton <akpm@linux-foundation.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/base.c40
1 files changed, 21 insertions, 19 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 34d11ac31f2e..53dc8ad40ae6 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1042,9 +1042,16 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
1042 err = -ESRCH; 1042 err = -ESRCH;
1043 goto out; 1043 goto out;
1044 } 1044 }
1045
1046 task_lock(task);
1047 if (!task->mm) {
1048 err = -EINVAL;
1049 goto err_task_lock;
1050 }
1051
1045 if (!lock_task_sighand(task, &flags)) { 1052 if (!lock_task_sighand(task, &flags)) {
1046 err = -ESRCH; 1053 err = -ESRCH;
1047 goto err_task_struct; 1054 goto err_task_lock;
1048 } 1055 }
1049 1056
1050 if (oom_adjust < task->signal->oom_adj && !capable(CAP_SYS_RESOURCE)) { 1057 if (oom_adjust < task->signal->oom_adj && !capable(CAP_SYS_RESOURCE)) {
@@ -1052,12 +1059,6 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
1052 goto err_sighand; 1059 goto err_sighand;
1053 } 1060 }
1054 1061
1055 task_lock(task);
1056 if (!task->mm) {
1057 err = -EINVAL;
1058 goto err_task_lock;
1059 }
1060
1061 if (oom_adjust != task->signal->oom_adj) { 1062 if (oom_adjust != task->signal->oom_adj) {
1062 if (oom_adjust == OOM_DISABLE) 1063 if (oom_adjust == OOM_DISABLE)
1063 atomic_inc(&task->mm->oom_disable_count); 1064 atomic_inc(&task->mm->oom_disable_count);
@@ -1083,11 +1084,10 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
1083 else 1084 else
1084 task->signal->oom_score_adj = (oom_adjust * OOM_SCORE_ADJ_MAX) / 1085 task->signal->oom_score_adj = (oom_adjust * OOM_SCORE_ADJ_MAX) /
1085 -OOM_DISABLE; 1086 -OOM_DISABLE;
1086err_task_lock:
1087 task_unlock(task);
1088err_sighand: 1087err_sighand:
1089 unlock_task_sighand(task, &flags); 1088 unlock_task_sighand(task, &flags);
1090err_task_struct: 1089err_task_lock:
1090 task_unlock(task);
1091 put_task_struct(task); 1091 put_task_struct(task);
1092out: 1092out:
1093 return err < 0 ? err : count; 1093 return err < 0 ? err : count;
@@ -1150,21 +1150,24 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
1150 err = -ESRCH; 1150 err = -ESRCH;
1151 goto out; 1151 goto out;
1152 } 1152 }
1153
1154 task_lock(task);
1155 if (!task->mm) {
1156 err = -EINVAL;
1157 goto err_task_lock;
1158 }
1159
1153 if (!lock_task_sighand(task, &flags)) { 1160 if (!lock_task_sighand(task, &flags)) {
1154 err = -ESRCH; 1161 err = -ESRCH;
1155 goto err_task_struct; 1162 goto err_task_lock;
1156 } 1163 }
1164
1157 if (oom_score_adj < task->signal->oom_score_adj && 1165 if (oom_score_adj < task->signal->oom_score_adj &&
1158 !capable(CAP_SYS_RESOURCE)) { 1166 !capable(CAP_SYS_RESOURCE)) {
1159 err = -EACCES; 1167 err = -EACCES;
1160 goto err_sighand; 1168 goto err_sighand;
1161 } 1169 }
1162 1170
1163 task_lock(task);
1164 if (!task->mm) {
1165 err = -EINVAL;
1166 goto err_task_lock;
1167 }
1168 if (oom_score_adj != task->signal->oom_score_adj) { 1171 if (oom_score_adj != task->signal->oom_score_adj) {
1169 if (oom_score_adj == OOM_SCORE_ADJ_MIN) 1172 if (oom_score_adj == OOM_SCORE_ADJ_MIN)
1170 atomic_inc(&task->mm->oom_disable_count); 1173 atomic_inc(&task->mm->oom_disable_count);
@@ -1181,11 +1184,10 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
1181 else 1184 else
1182 task->signal->oom_adj = (oom_score_adj * OOM_ADJUST_MAX) / 1185 task->signal->oom_adj = (oom_score_adj * OOM_ADJUST_MAX) /
1183 OOM_SCORE_ADJ_MAX; 1186 OOM_SCORE_ADJ_MAX;
1184err_task_lock:
1185 task_unlock(task);
1186err_sighand: 1187err_sighand:
1187 unlock_task_sighand(task, &flags); 1188 unlock_task_sighand(task, &flags);
1188err_task_struct: 1189err_task_lock:
1190 task_unlock(task);
1189 put_task_struct(task); 1191 put_task_struct(task);
1190out: 1192out:
1191 return err < 0 ? err : count; 1193 return err < 0 ? err : count;