[PATCH v9 4/4] lib/test_vmalloc: add vrealloc test case

Shivam Kalra via B4 Relay
2026-04-01T17:16:50Z

From: Shivam Kalra <shivamkalra98@zohomail.in>

Introduce a new test case "vrealloc_test" that exercises the vrealloc()
shrink and in-place grow paths:

- Grow beyond allocated pages (triggers full reallocation).
- Shrink crossing a page boundary (frees tail pages).
- Shrink within the same page (no page freeing).
- Grow within the already allocated page count (in-place).

Data integrity is validated after each realloc step by checking that
the first byte of the original allocation is preserved.

The test is gated behind run_test_mask bit 12 (id 4096).

Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Shivam Kalra <shivamkalra98@zohomail.in>
---
lib/test_vmalloc.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 62 insertions(+)

diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
index 876c72c18a0c..b23f85e8f8ca 100644
--- a/lib/test_vmalloc.c
+++ b/lib/test_vmalloc.c
@@ -55,6 +55,7 @@ __param(int, run_test_mask, 7,
"\t\tid: 512, name: kvfree_rcu_2_arg_vmalloc_test\n"
"\t\tid: 1024, name: vm_map_ram_test\n"
"\t\tid: 2048, name: no_block_alloc_test\n"
+ "\t\tid: 4096, name: vrealloc_test\n"
/* Add a new test case description here. */
);

@@ -421,6 +422,66 @@ vm_map_ram_test(void)
return nr_allocated != map_nr_pages;
}

+static int vrealloc_test(void)
+{
+ void *ptr, *tmp;
+ int i;
+
+ for (i = 0; i < test_loop_count; i++) {
+ int err = -1;
+
+ ptr = vrealloc(NULL, PAGE_SIZE, GFP_KERNEL);
+ if (!ptr)
+ return -1;
+
+ *((__u8 *)ptr) = 'a';
+
+ /* Grow: beyond allocated pages, triggers full realloc. */
+ tmp = vrealloc(ptr, 4 * PAGE_SIZE, GFP_KERNEL);
+ if (!tmp)
+ goto error;
+ ptr = tmp;
+
+ if (*((__u8 *)ptr) != 'a')
+ goto error;
+
+ /* Shrink: crosses page boundary, frees tail pages. */
+ tmp = vrealloc(ptr, PAGE_SIZE, GFP_KERNEL);
+ if (!tmp)
+ goto error;
+ ptr = tmp;
+
+ if (*((__u8 *)ptr) != 'a')
+ goto error;
+
+ /* Shrink: within same page, no page freeing. */
+ tmp = vrealloc(ptr, PAGE_SIZE / 2, GFP_KERNEL);
+ if (!tmp)
+ goto error;
+ ptr = tmp;
+
+ if (*((__u8 *)ptr) != 'a')
+ goto error;
+
+ /* Grow: within allocated page, in-place, no realloc. */
+ tmp = vrealloc(ptr, PAGE_SIZE, GFP_KERNEL);
+ if (!tmp)
+ goto error;
+ ptr = tmp;
+
+ if (*((__u8 *)ptr) != 'a')
+ goto error;
+
+ err = 0;
+error:
+ vfree(ptr);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
struct test_case_desc {
const char *test_name;
int (*test_func)(void);
@@ -440,6 +501,7 @@ static struct test_case_desc test_case_array[] = {
{ "kvfree_rcu_2_arg_vmalloc_test", kvfree_rcu_2_arg_vmalloc_test, },
{ "vm_map_ram_test", vm_map_ram_test, },
{ "no_block_alloc_test", no_block_alloc_test, true },
+ { "vrealloc_test", vrealloc_test, },
/* Add a new test case here. */
};

--
2.43.0