On Thu, Oct 16, 2025 at 10:03 PM Ben Copeland ben.copeland@linaro.org wrote:

The alloc_mem() function is supposed to test out of memory conditions. How it works is it calls mmap() on a giant chunk of memory. It's either LENGTH (2GB) or "TESTMEM * 2 + TST_MB" (3GB) bytes. This mmap() is generally supposed to succeed. Then at the bottom of the alloc_mem() function when we actually try to use all the memory, the thread is supposed to die with a SIGKILL.

The problem is that length is signed so on a 32-bit system it will be negative. That means that at the bottom of the function when we loop through the memory, the for loop is a no-op and there is no SIGKILL. Fix this by changing the type to size_t which is unsigned.

Signed-off-by: Ben Copeland ben.copeland@linaro.org

Reviewed-by: Li Wang liwang@redhat.com

---

testcases/kernel/mem/oom/oom.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/testcases/kernel/mem/oom/oom.h b/testcases/kernel/mem/oom/oom.h index 41cc681f9..42ed181b0 100644 --- a/testcases/kernel/mem/oom/oom.h +++ b/testcases/kernel/mem/oom/oom.h @@ -62,13 +62,14 @@ static inline void set_global_mempolicy(int mempolicy) static void set_global_mempolicy(int mempolicy LTP_ATTRIBUTE_UNUSED) { } #endif

-static int alloc_mem(long int length, int testcase) +static int alloc_mem(size_t length, int testcase) { char *s;

•   long i, pagesz = getpagesize();
  

•   size_t i;
  

•   long pagesz = getpagesize();
    int loop = 10;
  
  

•   tst_res(TINFO, "thread (%lx), allocating %ld bytes.",
  

•   tst_res(TINFO, "thread (%lx), allocating %zu bytes.",
            (unsigned long) pthread_self(), length);
  
    s = mmap(NULL, length, PROT_READ | PROT_WRITE,
  

@@ -111,7 +112,7 @@ static void child_alloc(int testcase, int lite, int threads) pthread_t *th;

    if (lite) {

•           int ret = alloc_mem(TESTMEM * 2 + TST_MB, testcase);
  

•           int ret = alloc_mem((size_t)TESTMEM * 2 + TST_MB,
  

testcase); exit(ret); }

-- 2.51.0

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