[LTP] [PATCH] hugemmap/hugemmap38: migrate libhugetlbfs test truncate_reserve_wraparound.c

[LTP] [PATCH] hugemmap/hugemmap38: migrate libhugetlbfs test truncate_reserve_wraparound.c

[Pavithra]

This test verifies that the kernel correctly maintains hugepage reservation
accounting when truncating a hugetlbfs file. It ensures that reserved
hugepages are properly tracked through the complete lifecycle

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap38.c  | 128 ++++++++++++++++++
 3 files changed, 130 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap38.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 8ee0e6f82..9dbee8555 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -37,6 +37,7 @@ hugemmap31 hugemmap31
 hugemmap32 hugemmap32
 hugemmap34 hugemmap34
 hugemmap35 hugemmap35
+hugemmap38 hugemmap38
 hugemmap05_1 hugemmap05 -m
 hugemmap05_2 hugemmap05 -s
 hugemmap05_3 hugemmap05 -s -m
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index 0e59035df..0e9547d99 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -37,6 +37,7 @@
 /hugetlb/hugemmap/hugemmap32
 /hugetlb/hugemmap/hugemmap34
 /hugetlb/hugemmap/hugemmap35
+/hugetlb/hugemmap/hugemmap38
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap38.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap38.c
new file mode 100644
index 000000000..4cefb5f78
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap38.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright (C) 2005-2006 David Gibson & Adam Litke, IBM Corporation.
+ * Copyright (c) 2026 Pavithra <pavrampu@linux.ibm.com>
+ */
+
+/*
+ * Origin: https://github.com/libhugetlbfs/libhugetlbfs/blob/master/tests/truncate_reserve_wraparound.c
+ */
+
+/*\
+ * Test that hugepage reservation accounting is correctly maintained when
+ * truncating a hugetlbfs file. This verifies that reserved hugepages are
+ * properly tracked through the sequence of: mmap (reserves page), touch
+ * (instantiates page), truncate (releases page), and attempted access
+ * (triggers SIGBUS). A bug in i_size handling could cause the reservation
+ * count to become incorrect, leading to resource leaks or allocation failures.
+ *
+ * Requires root to mount hugetlbfs.
+ */
+
+#include <signal.h>
+#include <setjmp.h>
+#include "hugetlb.h"
+
+#define MNTPOINT "hugetlbfs/"
+
+static long hpage_size;
+static int fd = -1;
+
+static sigjmp_buf sig_escape;
+
+static void sigbus_handler(int signum LTP_ATTRIBUTE_UNUSED)
+{
+	siglongjmp(sig_escape, 17);
+}
+
+static void run_test(void)
+{
+	volatile int sigbus_count = 0;
+	unsigned long initial_rsvd, after_map_rsvd, after_touch_rsvd;
+	unsigned long after_trunc_rsvd, after_unmap_rsvd, after_sigbus_rsvd;
+	volatile unsigned int *q;
+	void *p;
+
+	initial_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+	tst_res(TINFO, "Reserve count before map: %lu", initial_rsvd);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+			fd, 0);
+	q = p;
+
+	after_map_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd + 1, after_map_rsvd);
+	if (!TST_PASS)
+		goto windup;
+
+	*q = 0;
+	after_touch_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd, after_touch_rsvd);
+	if (!TST_PASS)
+		goto windup;
+
+	SAFE_FTRUNCATE(fd, 0);
+	after_trunc_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd, after_trunc_rsvd);
+	if (!TST_PASS)
+		goto windup;
+
+	if (sigsetjmp(sig_escape, 1) == 0)
+		*q; /* Fault, triggering a SIGBUS */
+	else
+		sigbus_count++;
+
+	if (sigbus_count != 1) {
+		tst_res(TFAIL, "Didn't SIGBUS after truncate");
+		goto windup;
+	}
+
+	after_sigbus_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd, after_sigbus_rsvd);
+	if (!TST_PASS)
+		goto windup;
+
+windup:
+	SAFE_MUNMAP(p, hpage_size);
+	after_unmap_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd, after_unmap_rsvd);
+}
+
+static void setup(void)
+{
+
+	hpage_size = tst_get_hugepage_size();
+	fd = tst_creat_unlinked(MNTPOINT, 0, 0600);
+
+	struct sigaction sa = {
+		.sa_handler = sigbus_handler,
+		.sa_flags = 0,
+	};
+
+	SAFE_SIGACTION(SIGBUS, &sa, NULL);
+}
+
+static void cleanup(void)
+{
+	if (fd != -1)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.tags = (struct tst_tag[]) {
+		{"linux-git", "ebed4bfc8da8"},
+		{}
+	},
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.needs_hugetlbfs = 1,
+	.hugepages = {4, TST_NEEDS},
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+};
-- 
2.55.0


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[LTP] [PATCH] hugemmap/hugemmap38: migrate libhugetlbfs test truncate_reserve_wraparound.c

[Pavithra]

This test verifies that the kernel correctly maintains hugepage reservation
accounting when truncating a hugetlbfs file. It ensures that reserved
hugepages are properly tracked through the complete lifecycle

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap38.c  | 127 ++++++++++++++++++
 3 files changed, 129 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap38.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 8ee0e6f82..9dbee8555 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -37,6 +37,7 @@ hugemmap31 hugemmap31
 hugemmap32 hugemmap32
 hugemmap34 hugemmap34
 hugemmap35 hugemmap35
+hugemmap38 hugemmap38
 hugemmap05_1 hugemmap05 -m
 hugemmap05_2 hugemmap05 -s
 hugemmap05_3 hugemmap05 -s -m
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index 0e59035df..0e9547d99 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -37,6 +37,7 @@
 /hugetlb/hugemmap/hugemmap32
 /hugetlb/hugemmap/hugemmap34
 /hugetlb/hugemmap/hugemmap35
+/hugetlb/hugemmap/hugemmap38
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap38.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap38.c
new file mode 100644
index 000000000..615de72b4
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap38.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright (C) 2005-2006 David Gibson & Adam Litke, IBM Corporation.
+ * Copyright (c) 2026 Pavithra <pavrampu@linux.ibm.com>
+ */
+
+/*
+ * Origin: https://github.com/libhugetlbfs/libhugetlbfs/blob/master/tests/truncate_reserve_wraparound.c
+ */
+
+/*\
+ * Test that hugepage reservation accounting is correctly maintained when
+ * truncating a hugetlbfs file. This verifies that reserved hugepages are
+ * properly tracked through the sequence of: mmap (reserves page), touch
+ * (instantiates page), truncate (releases page), and attempted access
+ * (triggers SIGBUS). A bug in i_size handling could cause the reservation
+ * count to become incorrect, leading to resource leaks or allocation failures.
+ *
+ * Requires root to mount hugetlbfs.
+ */
+
+#include <signal.h>
+#include <setjmp.h>
+#include "hugetlb.h"
+
+#define MNTPOINT "hugetlbfs/"
+
+static long hpage_size;
+static int fd = -1;
+
+static sigjmp_buf sig_escape;
+
+static void sigbus_handler(int signum LTP_ATTRIBUTE_UNUSED)
+{
+	siglongjmp(sig_escape, 17);
+}
+
+static void run_test(void)
+{
+	volatile int sigbus_count = 0;
+	unsigned long initial_rsvd, after_map_rsvd, after_touch_rsvd;
+	unsigned long after_trunc_rsvd, after_unmap_rsvd, after_sigbus_rsvd;
+	volatile unsigned int *q;
+	void *p;
+
+	initial_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+	tst_res(TINFO, "Reserve count before map: %lu", initial_rsvd);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+			fd, 0);
+	q = p;
+
+	after_map_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd + 1, after_map_rsvd);
+	if (!TST_PASS)
+		goto windup;
+
+	*q = 0;
+	after_touch_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd, after_touch_rsvd);
+	if (!TST_PASS)
+		goto windup;
+
+	SAFE_FTRUNCATE(fd, 0);
+	after_trunc_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd, after_trunc_rsvd);
+	if (!TST_PASS)
+		goto windup;
+
+	if (sigsetjmp(sig_escape, 1) == 0)
+		*q; /* Fault, triggering a SIGBUS */
+	else
+		sigbus_count++;
+
+	if (sigbus_count != 1) {
+		tst_res(TFAIL, "Didn't SIGBUS after truncate");
+		goto windup;
+	}
+
+	after_sigbus_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd, after_sigbus_rsvd);
+	if (!TST_PASS)
+		goto windup;
+
+windup:
+	SAFE_MUNMAP(p, hpage_size);
+	after_unmap_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(initial_rsvd, after_unmap_rsvd);
+}
+
+static void setup(void)
+{
+	hpage_size = tst_get_hugepage_size();
+	fd = tst_creat_unlinked(MNTPOINT, 0, 0600);
+
+	struct sigaction sa = {
+		.sa_handler = sigbus_handler,
+		.sa_flags = 0,
+	};
+
+	SAFE_SIGACTION(SIGBUS, &sa, NULL);
+}
+
+static void cleanup(void)
+{
+	if (fd != -1)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.tags = (struct tst_tag[]) {
+		{"linux-git", "ebed4bfc8da8"},
+		{}
+	},
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.needs_hugetlbfs = 1,
+	.hugepages = {1, TST_NEEDS},
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+};
-- 
2.55.0


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Re: [LTP] hugemmap/hugemmap38: migrate libhugetlbfs test truncate_reserve_wraparound.c

[linuxtestproject.agent]

Hi Pavithra,

On Sat, 18 Jul 2026 12:08:15 +0530, Pavithra wrote:
> hugemmap/hugemmap38: migrate libhugetlbfs test truncate_reserve_wraparound.c

> It ensures that reserved hugepages are properly tracked through the
> complete lifecycle

The sentence ends without a period and "the complete lifecycle" is left
unspecified. The doc comment inside the file describes the sequence as:
mmap (reserves page), touch (instantiates page), truncate (releases page),
and attempted access (triggers SIGBUS). Should the commit body spell that
out as well?

Verdict - Needs revision

---
Note:

The agent can sometimes produce false positives although often its
findings are genuine. If you find issues with the review, please
comment this email or ignore the suggestions.

Regards,
LTP AI Reviewer

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Re: [LTP] [PATCH] hugemmap/hugemmap38: migrate libhugetlbfs test truncate_reserve_wraparound.c

[Cyril Hrubis]

Hi!
Please add versions to the patch (git-format-patch with -v2, -v3, -v4)
so that it's clear which patch is the latest one.

-- 
Cyril Hrubis
chrubis@suse.cz

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