diff --git a/services/core/jni/com_android_server_am_CachedAppOptimizer.cpp b/services/core/jni/com_android_server_am_CachedAppOptimizer.cpp
index 8664c38af816c..1ff5002568a36 100644
--- a/services/core/jni/com_android_server_am_CachedAppOptimizer.cpp
+++ b/services/core/jni/com_android_server_am_CachedAppOptimizer.cpp
@@ -74,10 +74,12 @@ using android::base::unique_fd;
 // limit, it has to be a page aligned value, otherwise, compaction would fail.
 #define MAX_BYTES_PER_COMPACTION MAX_RW_COUNT
 
+// Selected a high enough number to avoid clashing with linux errno codes
+#define ERROR_COMPACTION_CANCELLED -1000
+
 namespace android {
 
-static bool cancelRunningCompaction;
-static bool compactionInProgress;
+static std::atomic<bool> cancelRunningCompaction;
 
 // Legacy method for compacting processes, any new code should
 // use compactProcess instead.
@@ -103,8 +105,6 @@ static int64_t compactMemory(const std::vector<Vma>& vmas, int pid, int madviseT
         // Skip compaction if failed to open pidfd with any error
         return -errno;
     }
-    compactionInProgress = true;
-    cancelRunningCompaction = false;
 
     int64_t totalBytesProcessed = 0;
 
@@ -113,14 +113,14 @@ static int64_t compactMemory(const std::vector<Vma>& vmas, int pid, int madviseT
         uint64_t bytesSentToCompact = 0;
         int iVec = 0;
         while (iVec < MAX_VMAS_PER_COMPACTION && iVma < vmas.size()) {
-            if (CC_UNLIKELY(cancelRunningCompaction)) {
+            if (CC_UNLIKELY(cancelRunningCompaction.load())) {
                 // There could be a significant delay between when a compaction
                 // is requested and when it is handled during this time our
                 // OOM adjust could have improved.
                 LOG(DEBUG) << "Cancelled running compaction for " << pid;
                 ATRACE_INSTANT_FOR_TRACK(ATRACE_COMPACTION_TRACK,
                                          StringPrintf("Cancelled compaction for %d", pid).c_str());
-                break;
+                return ERROR_COMPACTION_CANCELLED;
             }
 
             uint64_t vmaStart = vmas[iVma].start + vmaOffset;
@@ -150,11 +150,6 @@ static int64_t compactMemory(const std::vector<Vma>& vmas, int pid, int madviseT
             ++iVma;
         }
 
-        if (cancelRunningCompaction) {
-            cancelRunningCompaction = false;
-            break;
-        }
-
         ATRACE_BEGIN(StringPrintf("Compact %d VMAs", iVec).c_str());
         auto bytesProcessed = process_madvise(pidfd, vmasToKernel, iVec, madviseType, 0);
         ATRACE_END();
@@ -166,14 +161,12 @@ static int64_t compactMemory(const std::vector<Vma>& vmas, int pid, int madviseT
                 continue;
             } else {
                 // Forward irrecoverable errors and bail out compaction
-                compactionInProgress = false;
                 return -errno;
             }
         }
 
         totalBytesProcessed += bytesProcessed;
     }
-    compactionInProgress = false;
 
     return totalBytesProcessed;
 }
@@ -202,9 +195,12 @@ static int getAnyPageAdvice(const Vma& vma) {
 //
 // Currently supported behaviors are MADV_COLD and MADV_PAGEOUT.
 //
-// Returns the total number of bytes compacted or forwards an
-// process_madvise error.
+// Returns the total number of bytes compacted on success. On error
+// returns process_madvise errno code or if compaction was cancelled
+// it returns ERROR_COMPACTION_CANCELLED.
 static int64_t compactProcess(int pid, VmaToAdviseFunc vmaToAdviseFunc) {
+    cancelRunningCompaction.store(false);
+
     ProcMemInfo meminfo(pid);
     std::vector<Vma> pageoutVmas, coldVmas;
     auto vmaCollectorCb = [&coldVmas,&pageoutVmas,&vmaToAdviseFunc](const Vma& vma) {
@@ -223,12 +219,14 @@ static int64_t compactProcess(int pid, VmaToAdviseFunc vmaToAdviseFunc) {
     int64_t pageoutBytes = compactMemory(pageoutVmas, pid, MADV_PAGEOUT);
     if (pageoutBytes < 0) {
         // Error, just forward it.
+        cancelRunningCompaction.store(false);
         return pageoutBytes;
     }
 
     int64_t coldBytes = compactMemory(coldVmas, pid, MADV_COLD);
     if (coldBytes < 0) {
         // Error, just forward it.
+        cancelRunningCompaction.store(false);
         return coldBytes;
     }
 
@@ -308,10 +306,8 @@ static void com_android_server_am_CachedAppOptimizer_compactSystem(JNIEnv *, job
 }
 
 static void com_android_server_am_CachedAppOptimizer_cancelCompaction(JNIEnv*, jobject) {
-    if (compactionInProgress) {
-        cancelRunningCompaction = true;
-        ATRACE_INSTANT_FOR_TRACK(ATRACE_COMPACTION_TRACK, "Cancel compaction");
-    }
+    cancelRunningCompaction.store(true);
+    ATRACE_INSTANT_FOR_TRACK(ATRACE_COMPACTION_TRACK, "Cancel compaction");
 }
 
 static jdouble com_android_server_am_CachedAppOptimizer_getFreeSwapPercent(JNIEnv*, jobject) {