linux-kernel - [PATCH 4.3-rc6] proc: fix oom_adj value read from /proc/<pid>/oom

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Date:	Tue, 20 Oct 2015 12:34:36 +0000
From:	Hongjie Fang (方洪杰) 
	<Hongjie.Fang@...eadtrum.com>
To:	"ebiederm@...ssion.com" <ebiederm@...ssion.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH 4.3-rc6] proc: fix oom_adj value read from
 /proc/<pid>/oom_adj

The oom_adj's value reading through /proc/<pid>/oom_adj is different 
with the value written into /proc/<pid>/oom_adj. 
Fix this by adding a adjustment factor.

Signed-off-by: Hongjie Fang <hongjie.fang@...eadtrum.com>
---
diff --git a/fs/proc/base.c b/fs/proc/base.c
index b25eee4..1ea0589 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1043,6 +1043,7 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf,
 	int oom_adj;
 	unsigned long flags;
 	int err;
+	int adjust;
 
 	memset(buffer, 0, sizeof(buffer));
 	if (count > sizeof(buffer) - 1)
@@ -1084,8 +1085,10 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf,
 	 */
 	if (oom_adj == OOM_ADJUST_MAX)
 		oom_adj = OOM_SCORE_ADJ_MAX;
-	else
-		oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
+	else{
+		adjust = oom_adj > 0 ? (-OOM_DISABLE-1) : -(-OOM_DISABLE-1);
+		oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX + adjust) / -OOM_DISABLE;
+	}
 
 	if (oom_adj < task->signal->oom_score_adj &&
 	    !capable(CAP_SYS_RESOURCE)) {

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