Messages in this thread Patch in this message | | | From | "Wang, Biao" <> | Subject | [PATCH V3] staging: android: lowmemorykiller: imporve lmk to avoid deadlock issue | Date | Mon, 3 Aug 2015 08:26:40 +0000 |
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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@intel.com> Reviewed-by: Zhang Di <di.zhang@intel.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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