[PATCH] D76430: [scudo][standalone] Allow fallback to secondary if primary is full

[Kostya Kortchinsky via Phabricator via llvm-commits]

cryptoad updated this revision to Diff 251385.
cryptoad added a comment.

Initialize `Block` to `nullptr`.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D76430/new/

https://reviews.llvm.org/D76430

Files:
  compiler-rt/lib/scudo/standalone/combined.h
  compiler-rt/lib/scudo/standalone/tests/combined_test.cpp


Index: compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
===================================================================
--- compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
+++ compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
@@ -417,7 +417,7 @@
   Allocator->releaseToOS();
 }
 
-// Verify that when a region gets full, Android will still manage to
+// Verify that when a region gets full, the allocator will still manage to
 // fulfill the allocation through a larger size class.
 TEST(ScudoCombinedTest, FullRegion) {
   using AllocatorT = scudo::Allocator<DeathConfig>;
@@ -429,26 +429,25 @@
                                                            Deleter);
   Allocator->reset();
 
-  const scudo::uptr Size = 1000U;
-  const scudo::uptr MaxNumberOfChunks =
-      (1U << DeathRegionSizeLog) /
-      DeathConfig::DeathSizeClassMap::getSizeByClassId(1U);
-  void *P;
   std::vector<void *> V;
   scudo::uptr FailedAllocationsCount = 0;
-  for (scudo::uptr I = 0; I <= MaxNumberOfChunks; I++) {
-    P = Allocator->allocate(Size, Origin);
-    if (!P)
-      FailedAllocationsCount++;
-    else
-      V.push_back(P);
+  for (scudo::uptr ClassId = 1U;
+       ClassId <= DeathConfig::DeathSizeClassMap::LargestClassId; ClassId++) {
+    const scudo::uptr Size =
+        DeathConfig::DeathSizeClassMap::getSizeByClassId(ClassId);
+    const scudo::uptr MaxNumberOfChunks = (1U << DeathRegionSizeLog) / Size;
+    void *P;
+    for (scudo::uptr I = 0; I <= MaxNumberOfChunks; I++) {
+      P = Allocator->allocate(Size - 64U, Origin);
+      if (!P)
+        FailedAllocationsCount++;
+      else
+        V.push_back(P);
+    }
   }
   while (!V.empty()) {
     Allocator->deallocate(V.back(), Origin);
     V.pop_back();
   }
-  if (SCUDO_ANDROID)
-    EXPECT_EQ(FailedAllocationsCount, 0U);
-  else
-    EXPECT_GT(FailedAllocationsCount, 0U);
+  EXPECT_EQ(FailedAllocationsCount, 0U);
 }
Index: compiler-rt/lib/scudo/standalone/combined.h
===================================================================
--- compiler-rt/lib/scudo/standalone/combined.h
+++ compiler-rt/lib/scudo/standalone/combined.h
@@ -260,8 +260,8 @@
     }
     DCHECK_LE(Size, NeededSize);
 
-    void *Block;
-    uptr ClassId;
+    void *Block = nullptr;
+    uptr ClassId = 0;
     uptr SecondaryBlockEnd;
     if (LIKELY(PrimaryT::canAllocate(NeededSize))) {
       ClassId = SizeClassMap::getClassIdBySize(NeededSize);
@@ -273,20 +273,19 @@
       // is the region being full. In that event, retry once using the
       // immediately larger class (except if the failing class was already the
       // largest). This will waste some memory but will allow the application to
-      // not fail.
-      if (SCUDO_ANDROID) {
-        if (UNLIKELY(!Block)) {
-          if (ClassId < SizeClassMap::LargestClassId)
-            Block = TSD->Cache.allocate(++ClassId);
-        }
+      // not fail. If dealing with the largest class, fallback to the Secondary.
+      if (UNLIKELY(!Block)) {
+        if (ClassId < SizeClassMap::LargestClassId)
+          Block = TSD->Cache.allocate(++ClassId);
+        else
+          ClassId = 0;
       }
       if (UnlockRequired)
         TSD->unlock();
-    } else {
-      ClassId = 0;
+    }
+    if (UNLIKELY(ClassId == 0))
       Block = Secondary.allocate(NeededSize, Alignment, &SecondaryBlockEnd,
                                  ZeroContents);
-    }
 
     if (UNLIKELY(!Block)) {
       if (Options.MayReturnNull)


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