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Bolster fuzz coverage for HugeRegion. #533

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Bolster fuzz coverage for HugeRegion. #533

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3 changes: 3 additions & 0 deletions tcmalloc/BUILD
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Original file line number Diff line number Diff line change
Expand Up @@ -780,6 +780,9 @@ cc_test(
"@com_google_absl//absl/base:core_headers",
"@com_google_absl//absl/container:flat_hash_set",
"@com_google_absl//absl/log:check",
"@com_google_absl//absl/strings",
"@com_google_absl//absl/strings:str_format",
"@com_google_absl//absl/strings:string_view",
"@com_google_absl//absl/types:span",
"@com_google_fuzztest//fuzztest",
"@com_google_fuzztest//fuzztest:fuzztest_gtest_main",
Expand Down
63 changes: 56 additions & 7 deletions tcmalloc/huge_region_fuzz.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,9 @@
#include "absl/base/attributes.h"
#include "absl/container/flat_hash_set.h"
#include "absl/log/check.h"
#include "absl/strings/str_format.h"
#include "absl/strings/str_join.h"
#include "absl/strings/string_view.h"
#include "absl/types/span.h"
#include "tcmalloc/huge_cache.h"
#include "tcmalloc/huge_pages.h"
Expand Down Expand Up @@ -128,6 +131,17 @@ struct Toggle {
void Perform(State& state) const;
};

struct SetUnbackSuccess {
bool success;

template <typename Sink>
friend void AbslStringify(Sink& sink, const SetUnbackSuccess& s) {
absl::Format(&sink, "SetUnbackSuccess{.success=%v}", s.success);
}

void Perform(State& state) const;
};

struct Reentrant;

struct GatherStatsPbtxt {
Expand All @@ -148,8 +162,9 @@ struct PrintStats {
void Perform(State& state) const;
};

using Instruction = std::variant<Allocate, Deallocate, Release, Stats, Toggle,
Reentrant, GatherStatsPbtxt, PrintStats>;
using Instruction =
std::variant<Allocate, Deallocate, Release, Stats, Toggle, SetUnbackSuccess,
Reentrant, GatherStatsPbtxt, PrintStats>;

struct Reentrant {
std::vector<Instruction> subprogram;
Expand Down Expand Up @@ -230,6 +245,13 @@ struct State {
region.AddSpanStats(&small, &large);
TC_CHECK_LE(region.free_backed(), region.backed());
TC_CHECK_LE(region.backed(), region.size());
BackingStats stats = region.stats();
EXPECT_EQ(stats.system_bytes, HugeRegion::size().in_bytes());
EXPECT_EQ(stats.free_bytes, region.free_pages().in_bytes());
EXPECT_EQ(stats.unmapped_bytes, region.unmapped_pages().in_bytes());
EXPECT_EQ(
region.used_pages() + region.free_pages() + region.unmapped_pages(),
HugeRegion::size().in_pages());
}
};

Expand All @@ -240,6 +262,8 @@ void Allocate::Perform(State& state) const {
if (!state.region.MaybeGet(n, &p, &from_released)) {
return;
}
EXPECT_TRUE(state.region.contains(p));
EXPECT_TRUE(state.region.contains(p + n - Length(1)));
state.allocs.emplace_back(p, n);
if (!from_released) {
return;
Expand Down Expand Up @@ -276,23 +300,44 @@ void Release::Perform(State& state) const {
TC_CHECK_EQ(actual, NHugePages(0));
return;
}
if (max_expected > NHugePages(0) && len > Length(0)) {
TC_CHECK_GT(actual, NHugePages(0));
}
TC_CHECK_LE(actual, max_expected);
EXPECT_EQ(actual, max_expected);
}

void Stats::Perform(State& state) const {
state.region.stats();
SmallSpanStats small;
LargeSpanStats large;
state.region.AddSpanStats(&small, &large);

Length small_normal_pages;
Length small_returned_pages;
for (size_t i = 0; i < kMaxPages.raw_num(); ++i) {
small_normal_pages += Length(i * small.normal_length[i]);
small_returned_pages += Length(i * small.returned_length[i]);
}

EXPECT_EQ(small_normal_pages + large.normal_pages, state.region.free_pages());
EXPECT_EQ(small_returned_pages + large.returned_pages,
state.region.unmapped_pages());

BackingStats stats = state.region.stats();
EXPECT_EQ(stats.system_bytes, HugeRegion::size().in_bytes());
EXPECT_EQ(stats.free_bytes, state.region.free_pages().in_bytes());
EXPECT_EQ(stats.unmapped_bytes, state.region.unmapped_pages().in_bytes());
EXPECT_EQ(state.region.used_pages() + state.region.free_pages() +
state.region.unmapped_pages(),
HugeRegion::size().in_pages());
EXPECT_LE(state.region.free_backed(), state.region.backed());
EXPECT_LE(state.region.backed(), state.region.size());
}

void Toggle::Perform(State& state) const {
state.unback.unback_success_ = !state.unback.unback_success_;
}

void SetUnbackSuccess::Perform(State& state) const {
state.unback.unback_success_ = success;
}

void Reentrant::Perform(State& state) const {
state.reentrant_stack.push_back(subprogram);
}
Expand All @@ -309,6 +354,7 @@ void GatherStatsPbtxt::Perform(State& state) const {
void PrintStats::Perform(State& state) const {
Printer p(&state.output[0], state.output.size());
state.region.Print(p);
ASSERT_LE(p.SpaceRequired(), state.output.size());
}

void FuzzRegion(const std::vector<Instruction>& instructions,
Expand All @@ -331,6 +377,9 @@ auto GetFlatInstructionDomain() {
fuzztest::Arbitrary<Stats>()),
fuzztest::Map([](Toggle t) -> Instruction { return Instruction{t}; },
fuzztest::Arbitrary<Toggle>()),
fuzztest::Map(
[](SetUnbackSuccess s) -> Instruction { return Instruction{s}; },
fuzztest::Arbitrary<SetUnbackSuccess>()),
fuzztest::Map(
[](GatherStatsPbtxt g) -> Instruction { return Instruction{g}; },
fuzztest::Arbitrary<GatherStatsPbtxt>()),
Expand Down
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