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Message-ID: <09CB0B4607EB8F4DB7E0BE3B06BFBD051DA2E90F@SHSMSX101.ccr.corp.intel.com>
Date: Mon, 3 Aug 2015 08:26:40 +0000
From: "Wang, Biao" <biao.wang@...el.com>
To: "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"arve@...roid.com" <arve@...roid.com>,
"riandrews@...roid.com" <riandrews@...roid.com>
CC: "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Zhang, Di" <di.zhang@...el.com>, "Li, Fei" <fei.li@...el.com>,
"dan.carpenter@...cle.com" <dan.carpenter@...cle.com>,
"joe@...ches.com" <joe@...ches.com>
Subject: [PATCH V3] staging: android: lowmemorykiller: imporve lmk to avoid
deadlock issue
Consider the following case:
Task A trigger lmk with a lock held, while task B try to get this lock, but unfortunately B is the very culprit task lmk select to kill. Then B will never be killed, and A will forever select B to kill.
Such dead lock will trigger softlock up issue.
This patch try to pick the next task to break this loop.
Signed-off-by: Wang Biao <biao.wang@...el.com>
Reviewed-by: Zhang Di <di.zhang@...el.com>
---
drivers/staging/android/lowmemorykiller.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index feafa17..23d9832 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -127,9 +127,10 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
if (!p)
continue;
- if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
- time_before_eq(jiffies, lowmem_deathpending_timeout)) {
+ if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
task_unlock(p);
+ if (time_after(jiffies, lowmem_deathpending_timeout))
+ continue;
rcu_read_unlock();
return 0;
}
--
1.7.9.5
--
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