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Michal Hockotorvalds
Michal Hocko
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torvalds
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proc, oom_adj: extract oom_score_adj setting into a helper
Currently we have two proc interfaces to set oom_score_adj. The legacy /proc/<pid>/oom_adj and /proc/<pid>/oom_score_adj which both have their specific handlers. Big part of the logic is duplicated so extract the common code into __set_oom_adj helper. Legacy knob still expects some details slightly different so make sure those are handled same way - e.g. the legacy mode ignores oom_score_adj_min and it warns about the usage. This patch shouldn't introduce any functional changes. Link: http://lkml.kernel.org/r/1466426628-15074-4-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: David Rientjes <rientjes@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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‎fs/proc/base.c

Lines changed: 43 additions & 51 deletions
Original file line numberDiff line numberDiff line change
@@ -1037,7 +1037,47 @@ static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
10371037
return simple_read_from_buffer(buf, count, ppos, buffer, len);
10381038
}
10391039

1040-
static DEFINE_MUTEX(oom_adj_mutex);
1040+
static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
1041+
{
1042+
static DEFINE_MUTEX(oom_adj_mutex);
1043+
struct task_struct *task;
1044+
int err = 0;
1045+
1046+
task = get_proc_task(file_inode(file));
1047+
if (!task)
1048+
return -ESRCH;
1049+
1050+
mutex_lock(&oom_adj_mutex);
1051+
if (legacy) {
1052+
if (oom_adj < task->signal->oom_score_adj &&
1053+
!capable(CAP_SYS_RESOURCE)) {
1054+
err = -EACCES;
1055+
goto err_unlock;
1056+
}
1057+
/*
1058+
* /proc/pid/oom_adj is provided for legacy purposes, ask users to use
1059+
* /proc/pid/oom_score_adj instead.
1060+
*/
1061+
pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
1062+
current->comm, task_pid_nr(current), task_pid_nr(task),
1063+
task_pid_nr(task));
1064+
} else {
1065+
if ((short)oom_adj < task->signal->oom_score_adj_min &&
1066+
!capable(CAP_SYS_RESOURCE)) {
1067+
err = -EACCES;
1068+
goto err_unlock;
1069+
}
1070+
}
1071+
1072+
task->signal->oom_score_adj = oom_adj;
1073+
if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
1074+
task->signal->oom_score_adj_min = (short)oom_adj;
1075+
trace_oom_score_adj_update(task);
1076+
err_unlock:
1077+
mutex_unlock(&oom_adj_mutex);
1078+
put_task_struct(task);
1079+
return err;
1080+
}
10411081

10421082
/*
10431083
* /proc/pid/oom_adj exists solely for backwards compatibility with previous
@@ -1052,7 +1092,6 @@ static DEFINE_MUTEX(oom_adj_mutex);
10521092
static ssize_t oom_adj_write(struct file *file, const char __user *buf,
10531093
size_t count, loff_t *ppos)
10541094
{
1055-
struct task_struct *task;
10561095
char buffer[PROC_NUMBUF];
10571096
int oom_adj;
10581097
int err;
@@ -1074,12 +1113,6 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf,
10741113
goto out;
10751114
}
10761115

1077-
task = get_proc_task(file_inode(file));
1078-
if (!task) {
1079-
err = -ESRCH;
1080-
goto out;
1081-
}
1082-
10831116
/*
10841117
* Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum
10851118
* value is always attainable.
@@ -1089,26 +1122,7 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf,
10891122
else
10901123
oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
10911124

1092-
mutex_lock(&oom_adj_mutex);
1093-
if (oom_adj < task->signal->oom_score_adj &&
1094-
!capable(CAP_SYS_RESOURCE)) {
1095-
err = -EACCES;
1096-
goto err_unlock;
1097-
}
1098-
1099-
/*
1100-
* /proc/pid/oom_adj is provided for legacy purposes, ask users to use
1101-
* /proc/pid/oom_score_adj instead.
1102-
*/
1103-
pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
1104-
current->comm, task_pid_nr(current), task_pid_nr(task),
1105-
task_pid_nr(task));
1106-
1107-
task->signal->oom_score_adj = oom_adj;
1108-
trace_oom_score_adj_update(task);
1109-
err_unlock:
1110-
mutex_unlock(&oom_adj_mutex);
1111-
put_task_struct(task);
1125+
err = __set_oom_adj(file, oom_adj, true);
11121126
out:
11131127
return err < 0 ? err : count;
11141128
}
@@ -1138,7 +1152,6 @@ static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
11381152
static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
11391153
size_t count, loff_t *ppos)
11401154
{
1141-
struct task_struct *task;
11421155
char buffer[PROC_NUMBUF];
11431156
int oom_score_adj;
11441157
int err;
@@ -1160,28 +1173,7 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
11601173
goto out;
11611174
}
11621175

1163-
task = get_proc_task(file_inode(file));
1164-
if (!task) {
1165-
err = -ESRCH;
1166-
goto out;
1167-
}
1168-
1169-
mutex_lock(&oom_adj_mutex);
1170-
if ((short)oom_score_adj < task->signal->oom_score_adj_min &&
1171-
!capable(CAP_SYS_RESOURCE)) {
1172-
err = -EACCES;
1173-
goto err_unlock;
1174-
}
1175-
1176-
task->signal->oom_score_adj = (short)oom_score_adj;
1177-
if (has_capability_noaudit(current, CAP_SYS_RESOURCE))
1178-
task->signal->oom_score_adj_min = (short)oom_score_adj;
1179-
1180-
trace_oom_score_adj_update(task);
1181-
1182-
err_unlock:
1183-
mutex_unlock(&oom_adj_mutex);
1184-
put_task_struct(task);
1176+
err = __set_oom_adj(file, oom_score_adj, false);
11851177
out:
11861178
return err < 0 ? err : count;
11871179
}

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