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8366223: ZGC: ZPageAllocator::cleanup_failed_commit_multi_partition is broken

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Reviewed-by: stefank, jsikstro
This commit is contained in:
Axel Boldt-Christmas 2025-08-28 05:02:25 +00:00
parent 075ddef831
commit 501e6aed44
4 changed files with 122 additions and 2 deletions
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2
src/hotspot/share/gc/z/zPageAllocator.cpp
View File

@ -1941,7 +1941,7 @@ void ZPageAllocator::cleanup_failed_commit_multi_partition(ZMultiPartitionAlloca
}
const size_t committed = allocation->committed_capacity();
const ZVirtualMemory non_harvested_vmem = vmem.last_part(allocation->harvested());
const ZVirtualMemory non_harvested_vmem = partial_vmem.last_part(allocation->harvested());
const ZVirtualMemory committed_vmem = non_harvested_vmem.first_part(committed);
const ZVirtualMemory non_committed_vmem = non_harvested_vmem.last_part(committed);

13
src/hotspot/share/gc/z/zPhysicalMemoryManager.cpp
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@ -214,9 +214,20 @@ void ZPhysicalMemoryManager::free(const ZVirtualMemory& vmem, uint32_t numa_id)
});
}
static size_t inject_commit_limit(const ZVirtualMemory& vmem) {
// To facilitate easier interoperability with multi partition allocations we
// divide by ZNUMA::count(). Users of ZFailLargerCommits need to be aware of
// this when writing tests. In the future we could probe the VirtualMemoryManager
// and condition this division on whether the vmem is in the multi partition
// address space.
return align_up(MIN2(ZFailLargerCommits / ZNUMA::count(), vmem.size()), ZGranuleSize);
}
size_t ZPhysicalMemoryManager::commit(const ZVirtualMemory& vmem, uint32_t numa_id) {
zbacking_index* const pmem = _physical_mappings.addr(vmem.start());
const size_t size = vmem.size();
const size_t size = ZFailLargerCommits > 0
? inject_commit_limit(vmem)
: vmem.size();
size_t total_committed = 0;

5
src/hotspot/share/gc/z/z_globals.hpp
View File

@ -118,6 +118,11 @@
develop(bool, ZVerifyOops, false, \
"Verify accessed oops") \
\
develop(size_t, ZFailLargerCommits, 0, \
"Commits larger than ZFailLargerCommits will be truncated, " \
"used to stress page allocation commit failure paths " \
"(0: Disabled)") \
\
develop(uint, ZFakeNUMA, 1, \
"ZFakeNUMA is used to test the internal NUMA memory support " \
"without the need for UseNUMA") \

104
test/hotspot/jtreg/gc/z/TestCommitFailure.java Normal file
View File

@ -0,0 +1,104 @@
/*
* Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package gc.z;
/*
* @test id=ZFakeNUMA
* @requires vm.gc.Z & vm.debug
* @library / /test/lib
* @summary Test ZGC graceful failure when a commit fails (with ZFakeNUMA)
* @run driver gc.z.TestCommitFailure -XX:ZFakeNUMA=16
*/
import jdk.test.lib.process.ProcessTools;
import static gc.testlibrary.Allocation.blackHole;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class TestCommitFailure {
static final int K = 1024;
static final int M = 1024 * K;
static final int XMS = 128 * M;
static final int XMX = 512 * M;
static class Test {
static final int LARGE_ALLOC = 256 * M;
static final int SMALL_GARBAGE = 256 * M;
static final int SMALL_LIVE = 128 * M;
// Allocates at least totalLive bytes of objects and add them to list.
static void allocLive(List<Object> list, int totalLive) {
final int largePageAllocationSize = 6 * M;
for (int live = 0; live < totalLive; live += largePageAllocationSize) {
list.add(new byte[largePageAllocationSize - K]);
}
}
// Allocates at least totalGarbage bytes of garbage large pages.
static void allocGarbage(int totalGarbage) {
final int largePageAllocationSize = 6 * M;
for (int garbage = 0; garbage < totalGarbage; garbage += largePageAllocationSize) {
blackHole(new byte[largePageAllocationSize - K]);
}
}
public static void main(String[] args) {
final var list = new ArrayList<Object>();
try {
// Fill heap with small live objects
allocLive(list, SMALL_LIVE);
// Fill with small garbage objects
allocGarbage(SMALL_GARBAGE);
// Allocate large objects where commit fails until an OOME is thrown
while (true) {
list.add(new byte[LARGE_ALLOC - K]);
}
} catch (OutOfMemoryError oome) {}
blackHole(list);
}
}
public static void main(String[] args) throws Exception {
final int xmxInM = XMX / M;
final int xmsInM = XMS / M;
final var arguments = new ArrayList(Arrays.asList(args));
arguments.addAll(List.of(
"-XX:+UseZGC",
"-Xlog:gc+init",
"-XX:ZFailLargerCommits=" + XMS,
"-Xms" + xmsInM + "M",
"-Xmx" + xmxInM + "M",
Test.class.getName()));
ProcessTools.executeTestJava(arguments)
.outputTo(System.out)
.errorTo(System.out)
.shouldContain("Forced to lower max Java heap size")
.shouldHaveExitValue(0);
}
}