Skip machine-level hugepage fragmentation stats during OOM dumps. - #1040
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Root Cause: During OOM crash reporting in PrintStats(), TCMalloc_Internal_GetStats() is invoked with kStatsBufferSize = 16 KiB (>= 10,000 bytes), triggering DumpStats(printer, 2). DumpStats() unconditionally reads /sys/devices/system/node/node*/hugepage_fragmentation_ratio via GetHugepageFragmentationRatio(), contending on kernel zone->lock across concurrent processes and causing death test timeouts in logging_test and limit_test. Reducing kStatsBufferSize to 8 KiB invokes DumpStats(printer, 1), and gating GetHugepageFragmentationRatio() behind level >= 2 avoids kernel sysfs reads during OOM crash dumps while retaining full fragmentation telemetry in MallocExtension::GetStats(). PiperOrigin-RevId: 981595248
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Skip machine-level hugepage fragmentation stats during OOM dumps.
Root Cause:
During OOM crash reporting in PrintStats(), TCMalloc_Internal_GetStats() is invoked with kStatsBufferSize = 16 KiB (>= 10,000 bytes), triggering DumpStats(printer, 2). DumpStats() unconditionally reads /sys/devices/system/node/node*/hugepage_fragmentation_ratio via GetHugepageFragmentationRatio(), contending on kernel zone->lock across concurrent processes and causing death test timeouts in logging_test and limit_test.
Reducing kStatsBufferSize to 8 KiB invokes DumpStats(printer, 1), and gating GetHugepageFragmentationRatio() behind level >= 2 avoids kernel sysfs reads during OOM crash dumps while retaining full fragmentation telemetry in MallocExtension::GetStats().