[PATCH] D82070: [scudo][standalone] Allow Primary allocations to fail up multiple times.

[Kostya Kortchinsky via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGe7ac984dc055: [scudo][standalone] Allow Primary allocations to fail up multiple times. (authored by cferris, committed by cryptoad).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D82070/new/

https://reviews.llvm.org/D82070

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
@@ -385,14 +385,14 @@
   static const scudo::uptr NumBits = 1;
   static const scudo::uptr MinSizeLog = 10;
   static const scudo::uptr MidSizeLog = 10;
-  static const scudo::uptr MaxSizeLog = 11;
+  static const scudo::uptr MaxSizeLog = 13;
   static const scudo::u32 MaxNumCachedHint = 4;
   static const scudo::uptr MaxBytesCachedLog = 12;
 };
 
 static const scudo::uptr DeathRegionSizeLog = 20U;
 struct DeathConfig {
-  // Tiny allocator, its Primary only serves chunks of two sizes.
+  // Tiny allocator, its Primary only serves chunks of four sizes.
   using DeathSizeClassMap = scudo::FixedSizeClassMap<DeathSizeClassConfig>;
   typedef scudo::SizeClassAllocator64<DeathSizeClassMap, DeathRegionSizeLog>
       Primary;
@@ -472,7 +472,10 @@
        ClassId <= DeathConfig::DeathSizeClassMap::LargestClassId; ClassId++) {
     const scudo::uptr Size =
         DeathConfig::DeathSizeClassMap::getSizeByClassId(ClassId);
-    const scudo::uptr MaxNumberOfChunks = (1U << DeathRegionSizeLog) / Size;
+    // Allocate enough to fill all of the regions above this one.
+    const scudo::uptr MaxNumberOfChunks =
+        ((1U << DeathRegionSizeLog) / Size) *
+        (DeathConfig::DeathSizeClassMap::LargestClassId - ClassId + 1);
     void *P;
     for (scudo::uptr I = 0; I <= MaxNumberOfChunks; I++) {
       P = Allocator->allocate(Size - 64U, Origin);
@@ -481,10 +484,10 @@
       else
         V.push_back(P);
     }
-  }
-  while (!V.empty()) {
-    Allocator->deallocate(V.back(), Origin);
-    V.pop_back();
+    while (!V.empty()) {
+      Allocator->deallocate(V.back(), Origin);
+      V.pop_back();
+    }
   }
   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
@@ -297,16 +297,20 @@
       bool UnlockRequired;
       auto *TSD = TSDRegistry.getTSDAndLock(&UnlockRequired);
       Block = TSD->Cache.allocate(ClassId);
-      // If the allocation failed, the most likely reason with a 64-bit primary
-      // 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 dealing with the largest class, fallback to the Secondary.
+      // If the allocation failed, the most likely reason with a 32-bit primary
+      // is the region being full. In that event, retry in each successively
+      // larger class until it fits. If it fails to fit in the largest class,
+      // fallback to the Secondary.
       if (UNLIKELY(!Block)) {
-        if (ClassId < SizeClassMap::LargestClassId)
+        while (ClassId < SizeClassMap::LargestClassId) {
           Block = TSD->Cache.allocate(++ClassId);
-        else
+          if (LIKELY(Block)) {
+            break;
+          }
+        }
+        if (UNLIKELY(!Block)) {
           ClassId = 0;
+        }
       }
       if (UnlockRequired)
         TSD->unlock();


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