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Avoid data race on sampled stack trace during sampled deallocation. #682

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12 changes: 8 additions & 4 deletions tcmalloc/allocation_sampling.h
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Original file line number Diff line number Diff line change
Expand Up @@ -398,23 +398,26 @@ void MaybeUnsampleAllocation(Static& state, Policy policy,
static_cast<double>(weight) / (requested_size + 1);
AllocHandle sampled_alloc_handle =
sampled_allocation->sampled_stack.sampled_alloc_handle;
void* stack_copy[kMaxStackDepth];
const size_t depth = sampled_allocation->sampled_stack.depth;
TC_ASSERT_LE(depth, kMaxStackDepth);
memcpy(stack_copy, sampled_allocation->sampled_stack.stack,
depth * sizeof(void*));
MallocHook::SampledAlloc sampled_alloc = {
.handle = sampled_alloc_handle,
.requested_size = requested_size,
.requested_alignment =
sampled_allocation->sampled_stack.requested_alignment,
.allocated_size = allocated_size,
.weight = allocation_estimate,
.stack = absl::MakeSpan(sampled_allocation->sampled_stack.stack,
sampled_allocation->sampled_stack.depth),
.stack = absl::MakeSpan(stack_copy, depth),
.allocation_time = sampled_allocation->sampled_stack.allocation_time,
.ptr = ptr,
.access_hint = sampled_allocation->sampled_stack.access_hint,
.access_allocated = sampled_allocation->sampled_stack.cold_allocated
? MallocHook::Access::Cold
: MallocHook::Access::Hot,
};
state.sampled_allocation_recorder().Unregister(sampled_allocation);

// Adjust our estimate of internal fragmentation.
TC_ASSERT_LE(requested_size, allocated_size);
Expand All @@ -427,8 +430,9 @@ void MaybeUnsampleAllocation(Static& state, Policy policy,
sampled_fragmentation);
state.sampled_internal_fragmentation_.Add(-sampled_fragmentation);
}
MallocHook::InvokeSampledDeleteHook(sampled_alloc);

state.sampled_allocation_recorder().Unregister(sampled_allocation);
MallocHook::InvokeSampledDeleteHook(sampled_alloc);
state.deallocation_samples.ReportFree(sampled_alloc_handle);
}

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26 changes: 18 additions & 8 deletions tcmalloc/huge_page_tracker.h
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Expand Up @@ -437,21 +437,31 @@ inline PageTracker::HardwarePageResidencyInfo PageTracker::CountInfoInHugePage(
}
TC_ASSERT_LE(kHardwarePagesInHugePage, kMaxResidencyBits);

const PageBitmap& used = free_.bits();
const PageBitmap free = ~used;
const PageBitmap& free = free_.bits();

TC_ASSERT_EQ(kHardwarePagesInHugePage % kPagesPerHugePage.raw_num(), 0);
const int shift = kHardwarePagesInHugePage / kPagesPerHugePage.raw_num();
const int shift_bits = absl::bit_width<uint8_t>(shift - 1);
TC_ASSERT_LT((kHardwarePagesInHugePage - 1) >> shift_bits,
kPagesPerHugePage.raw_num());

return {.n_free_swapped = (free & swapped).CountBits() * shift,
.n_used_swapped = (used & swapped).CountBits() * shift,
.n_free_unbacked = (free & unbacked).CountBits() * shift,
.n_used_unbacked = (used & unbacked).CountBits() * shift,
.n_free_stale = (free & stale).CountBits() * shift,
.n_used_stale = (used & stale).CountBits() * shift};
size_t n_unbacked[2] = {0, 0};
size_t n_swapped[2] = {0, 0};
size_t n_stale[2] = {0, 0};

n_unbacked[0] = (free & unbacked).CountBits() * shift;
n_unbacked[1] = (~free & unbacked).CountBits() * shift;
n_swapped[0] = (free & swapped).CountBits() * shift;
n_swapped[1] = (~free & swapped).CountBits() * shift;
n_stale[0] = (free & stale).CountBits() * shift;
n_stale[1] = (~free & stale).CountBits() * shift;

return {.n_free_swapped = n_swapped[1],
.n_used_swapped = n_swapped[0],
.n_free_unbacked = n_unbacked[1],
.n_used_unbacked = n_unbacked[0],
.n_free_stale = n_stale[1],
.n_used_stale = n_stale[0]};
}

inline void PageTracker::Put(Range r, SpanAllocInfo span_alloc_info) {
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