From 98df1b8ef2f8b904e1b032fff42e46b9b627b14e Mon Sep 17 00:00:00 2001 From: Jeff Vander Stoep Date: Wed, 22 Nov 2017 23:09:23 -0800 Subject: [PATCH] Check for /dev/memcg/system/tasks before writing to it Fixes the following errors in the logs on devices without /dev/memcg mounted: 09-08 10:07:22.991 732 732 E Zygote : couldn't write 1124 to /dev/memcg/system/tasks 09-08 10:07:22.986 732 732 W main : type=1400 audit(0.0:8): avc: denied { create } for name="tasks" scontext=u:r:zygote:s0 tcontext=u:object_r:cgroup:s0 tclass=file permissive=0 Bug: 67860826 Test: boot Taimen, no more error/denial in the logs. Change-Id: I37f481fa4e9e9116688cca4f090aa26f96f602c9 Merged-In: I37f481fa4e9e9116688cca4f090aa26f96f602c9 (cherry picked from commit 6bdc3a28e75bdb936e7c172bc8d305b2c30c9f06) --- core/jni/com_android_internal_os_Zygote.cpp | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/core/jni/com_android_internal_os_Zygote.cpp b/core/jni/com_android_internal_os_Zygote.cpp index 8d6a2800a45d3..c2582203afde5 100644 --- a/core/jni/com_android_internal_os_Zygote.cpp +++ b/core/jni/com_android_internal_os_Zygote.cpp @@ -908,7 +908,10 @@ static jint com_android_internal_os_Zygote_nativeForkSystemServer( } // Assign system_server to the correct memory cgroup. - if (!WriteStringToFile(StringPrintf("%d", pid), "/dev/memcg/system/tasks")) { + // Not all devices mount /dev/memcg so check for the file first + // to avoid unnecessarily printing errors and denials in the logs. + if (!access("/dev/memcg/system/tasks", F_OK) && + !WriteStringToFile(StringPrintf("%d", pid), "/dev/memcg/system/tasks")) { ALOGE("couldn't write %d to /dev/memcg/system/tasks", pid); } }