From a7add488ae63fc2574dda97791cbc65fe67f7771 Mon Sep 17 00:00:00 2001
From: Evgeniy Stepanov <eugeni.stepanov@gmail.com>
Date: Thu, 31 Oct 2013 15:51:22 +0000
Subject: [msan] Disable mlock/mlockall to work around a linux kernel bug.

The same logic is present in ASan and TSan.

llvm-svn: 193755
---
 compiler-rt/lib/msan/msan_interceptors.cc | 29 +++++++++++++++++++++++++++++
 compiler-rt/lib/msan/tests/msan_test.cc   |  7 +++++++
 2 files changed, 36 insertions(+)

diff --git a/compiler-rt/lib/msan/msan_interceptors.cc b/compiler-rt/lib/msan/msan_interceptors.cc
index 360d5a19453..8c867c3bcde 100644
--- a/compiler-rt/lib/msan/msan_interceptors.cc
+++ b/compiler-rt/lib/msan/msan_interceptors.cc
@@ -1172,6 +1172,35 @@ INTERCEPTOR(void *, shmat, int shmid, const void *shmaddr, int shmflg) {
   return p;
 }
 
+// Linux kernel has a bug that leads to kernel deadlock if a process
+// maps TBs of memory and then calls mlock().
+static void MlockIsUnsupported() {
+  static atomic_uint8_t printed;
+  if (atomic_exchange(&printed, 1, memory_order_relaxed))
+    return;
+  if (common_flags()->verbosity > 0)
+    Printf("INFO: MemorySanitizer ignores mlock/mlockall/munlock/munlockall\n");
+}
+
+INTERCEPTOR(int, mlock, const void *addr, uptr len) {
+  MlockIsUnsupported();
+  return 0;
+}
+
+INTERCEPTOR(int, munlock, const void *addr, uptr len) {
+  MlockIsUnsupported();
+  return 0;
+}
+
+INTERCEPTOR(int, mlockall, int flags) {
+  MlockIsUnsupported();
+  return 0;
+}
+
+INTERCEPTOR(int, munlockall, void) {
+  MlockIsUnsupported();
+  return 0;
+}
 
 struct MSanInterceptorContext {
   bool in_interceptor_scope;
diff --git a/compiler-rt/lib/msan/tests/msan_test.cc b/compiler-rt/lib/msan/tests/msan_test.cc
index 2269bb23749..ab109874bc2 100644
--- a/compiler-rt/lib/msan/tests/msan_test.cc
+++ b/compiler-rt/lib/msan/tests/msan_test.cc
@@ -3496,3 +3496,10 @@ TEST(MemorySanitizerAllocator, get_allocated_size_and_ownership) {
 
   delete int_ptr;
 }
+
+TEST(MemorySanitizer, MlockTest) {
+  EXPECT_EQ(0, mlockall(MCL_CURRENT));
+  EXPECT_EQ(0, mlock((void*)0x12345, 0x5678));
+  EXPECT_EQ(0, munlockall());
+  EXPECT_EQ(0, munlock((void*)0x987, 0x654));
+}
-- 
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