[scudo] Make release to OS test more specific.#147852
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cferris1000 merged 2 commits intollvm:mainfrom Jul 17, 2025
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The original version of ResidentMemorySize could be a little flaky. Replace the test with a version that verifies exactly how much of the map is resident.
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@llvm/pr-subscribers-compiler-rt-sanitizer Author: Christopher Ferris (cferris1000) ChangesThe original version of ResidentMemorySize could be a little flaky. Replace the test with a version that verifies exactly how much of the map is resident. Full diff: https://github.com/llvm/llvm-project/pull/147852.diff 1 Files Affected:
diff --git a/compiler-rt/lib/scudo/standalone/tests/common_test.cpp b/compiler-rt/lib/scudo/standalone/tests/common_test.cpp
index e6ddbb00b843c..df692aca99621 100644
--- a/compiler-rt/lib/scudo/standalone/tests/common_test.cpp
+++ b/compiler-rt/lib/scudo/standalone/tests/common_test.cpp
@@ -11,44 +11,136 @@
#include "common.h"
#include "mem_map.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
#include <algorithm>
-#include <fstream>
+#include <string>
namespace scudo {
-static uptr getResidentMemorySize() {
+static void GetRssKbFromString(uptr MapAddress, std::string &Buffer,
+ size_t &ParsedBytes, size_t &RssKb,
+ bool &Found) {
+ size_t LineStart = 0;
+ bool FindRss = false;
+ while (true) {
+ size_t LineEnd = Buffer.find('\n', LineStart);
+ if (LineEnd == std::string::npos) {
+ ParsedBytes = LineStart;
+ ASSERT_NE(0U, ParsedBytes)
+ << "The current buffer size (" << Buffer.size()
+ << ") is not large enough to contain a single line.";
+ break;
+ }
+ Buffer[LineEnd] = '\0';
+ // The format of the address line is:
+ // 55ecba642000-55ecba644000 r--p 00000000 fd:01 66856632
+ uptr StartAddr;
+ uptr EndAddr;
+ char Perms[5];
+ if (sscanf(&Buffer[LineStart], "%" SCNxPTR "-%" SCNxPTR " %4s", &StartAddr,
+ &EndAddr, Perms) == 3) {
+ if (StartAddr == MapAddress) {
+ FindRss = true;
+ }
+ } else if (FindRss && strncmp(&Buffer[LineStart], "Rss:", 4) == 0) {
+ // The format of the RSS line is:
+ // Rss: 8 kB
+ ASSERT_EQ(1, sscanf(&Buffer[LineStart], "Rss: %zd kB", &RssKb))
+ << "Bad Rss Line: " << &Buffer[LineStart];
+ Found = true;
+ ParsedBytes = LineStart;
+ break;
+ }
+ LineStart = LineEnd + 1;
+ }
+}
+
+static void GetRssKb(void *BaseAddress, size_t &RssKb) {
if (!SCUDO_LINUX)
UNREACHABLE("Not implemented!");
- uptr Size;
- uptr Resident;
- std::ifstream IFS("/proc/self/statm");
- IFS >> Size;
- IFS >> Resident;
- return Resident * getPageSizeCached();
+
+ size_t MapAddress = reinterpret_cast<size_t>(BaseAddress);
+
+ int Fd = open("/proc/self/smaps", O_RDONLY);
+ ASSERT_NE(-1, Fd) << "Failed to open /proc/self/smaps: " << strerror(errno);
+
+ std::string Buffer(10 * 1024, '\0');
+ size_t LeftoverBytes = 0;
+ RssKb = 0;
+ bool FoundMap = false;
+ while (LeftoverBytes != Buffer.size()) {
+ ssize_t ReadBytes =
+ read(Fd, &Buffer[LeftoverBytes], Buffer.size() - LeftoverBytes);
+ if (ReadBytes < 0) {
+ EXPECT_GT(0, ReadBytes) << "read failed: " << strerror(errno);
+ break;
+ }
+ if (ReadBytes == 0) {
+ // Nothing left to read.
+ break;
+ }
+ size_t End = static_cast<size_t>(ReadBytes) + LeftoverBytes;
+ Buffer[End] = '\0';
+ size_t ParsedBytes = 0;
+ GetRssKbFromString(MapAddress, Buffer, ParsedBytes, RssKb, FoundMap);
+ if (TEST_HAS_FAILURE || FoundMap)
+ break;
+ // Need to copy the leftover bytes back to the front of the buffer.
+ LeftoverBytes = End - ParsedBytes;
+ if (LeftoverBytes != 0) {
+ memmove(Buffer.data(), &Buffer[ParsedBytes], LeftoverBytes);
+ }
+ }
+ close(Fd);
+
+ EXPECT_TRUE(FoundMap) << "Could not find map at address " << BaseAddress;
}
-// Fuchsia needs getResidentMemorySize implementation.
+// Fuchsia needs getRssKb implementation.
TEST(ScudoCommonTest, SKIP_ON_FUCHSIA(ResidentMemorySize)) {
- uptr OnStart = getResidentMemorySize();
- EXPECT_GT(OnStart, 0UL);
-
- const uptr Size = 1ull << 30;
- const uptr Threshold = Size >> 3;
+ // Make sure to have the size of the map on a page boundary.
+ const uptr PageSize = getPageSizeCached();
+ const uptr SizeBytes = 1000 * PageSize;
+ const uptr ActualSizeBytes = SizeBytes - 2 * PageSize;
MemMapT MemMap;
- ASSERT_TRUE(MemMap.map(/*Addr=*/0U, Size, "ResidentMemorySize"));
+ ASSERT_TRUE(MemMap.map(/*Addr=*/0U, SizeBytes, "ResidentMemorySize"));
ASSERT_NE(MemMap.getBase(), 0U);
- void *P = reinterpret_cast<void *>(MemMap.getBase());
- EXPECT_LT(getResidentMemorySize(), OnStart + Threshold);
- memset(P, 1, Size);
- EXPECT_GT(getResidentMemorySize(), OnStart + Size - Threshold);
-
- MemMap.releasePagesToOS(MemMap.getBase(), Size);
- EXPECT_LT(getResidentMemorySize(), OnStart + Threshold);
-
- memset(P, 1, Size);
- EXPECT_GT(getResidentMemorySize(), OnStart + Size - Threshold);
+ // Mark the first page and the last page as unreadable to make sure that
+ // the map shows up as distinct from all other maps.
+ EXPECT_EQ(0, mprotect(reinterpret_cast<void *>(MemMap.getBase()), PageSize,
+ PROT_NONE));
+ EXPECT_EQ(0, mprotect(reinterpret_cast<void *>(MemMap.getBase() + SizeBytes -
+ PageSize),
+ PageSize, PROT_NONE));
+
+ size_t RssKb = 0;
+ void *P = reinterpret_cast<void *>(MemMap.getBase() + PageSize);
+ GetRssKb(P, RssKb);
+ EXPECT_EQ(RssKb, 0U);
+
+ // Make the entire map resident.
+ memset(P, 1, ActualSizeBytes);
+ GetRssKb(P, RssKb);
+ EXPECT_EQ(RssKb, (ActualSizeBytes >> 10));
+
+ // Should release the memory to the kernel immediately.
+ MemMap.releasePagesToOS(MemMap.getBase(), SizeBytes);
+ GetRssKb(P, RssKb);
+ EXPECT_EQ(RssKb, 0U);
+
+ // Make the entire map resident again.
+ memset(P, 1, ActualSizeBytes);
+ GetRssKb(P, RssKb);
+ EXPECT_EQ(RssKb, ActualSizeBytes >> 10);
MemMap.unmap();
}
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Contributor
ChiaHungDuan
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Will mincore() help with the test here?
Contributor
Author
Yes, that is exactly what I should have used. I have modified the code to use mincore. |
ChiaHungDuan
approved these changes
Jul 16, 2025
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/11/builds/19734 Here is the relevant piece of the build log for the reference |
This was referenced Jul 23, 2025
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The original version of ResidentMemorySize could be a little flaky. Replace the test with a version that verifies exactly how much of the map is resident.