commit 1be86db9c8fa8a57bc4f21dbc51140b33d02d7cd
author Daniel Colascione <dancol@google.com> Wed Jan 24 08:31:28 2018 +0000
committer android-build-merger <android-build-merger@google.com> Wed Jan 24 08:31:28 2018 +0000
tree 025ee6c52ec0e1ca20fb641273fb9f0172ffce08
parent 4e0c262015f8cb074f5414a36c00dcf65d8a612d
parent 5d0126a331953bf03ecd1b29a85405c60e0ae11a

Merge "Add MCL_ONFAULT to mlockall" am: ccb9960beb am: 179c81f733
am: 1592d9b458

Change-Id: I55420b49d0902dc00b5741294c05a1320bf13325

lmkd/lmkd.c

diff --git a/lmkd/lmkd.c b/lmkd/lmkd.c
index 3230310..838a5f4 100644
--- a/lmkd/lmkd.c
+++ b/lmkd/lmkd.c
@@ -1112,7 +1112,16 @@
     kill_timeout_ms =
         (unsigned long)property_get_int32("ro.lmk.kill_timeout_ms", 0);
 
-    if (mlockall(MCL_CURRENT | MCL_FUTURE))
+    // MCL_ONFAULT pins pages as they fault instead of loading
+    // everything immediately all at once. (Which would be bad,
+    // because as of this writing, we have a lot of mapped pages we
+    // never use.) Old kernels will see MCL_ONFAULT and fail with
+    // EINVAL; we ignore this failure.
+    //
+    // N.B. read the man page for mlockall. MCL_CURRENT | MCL_ONFAULT
+    // pins ⊆ MCL_CURRENT, converging to just MCL_CURRENT as we fault
+    // in pages.
+    if (mlockall(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT) && errno != EINVAL)
         ALOGW("mlockall failed: errno=%d", errno);
 
     sched_setscheduler(0, SCHED_FIFO, &param);