The overcommit test uses sum_total, the sum (memory and swap) to test the overcommit settings.

This fixes two problems on 32-bit systems. The first is seen with a integer overflow can occur when calculating sum_total * 2, if the sum_total is larger than 2GB. The second is limited virtual address space (2-3GB) means the test can fail from address space exhaustion before overcommit has been tested.

Now the test runs correctly on low-memory 32-bit systems while avoiding both the overflow bug and virtual address space issues.

Signed-off-by: Ben Copeland ben.copeland@linaro.org --- .../kernel/mem/tunable/overcommit_memory.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/testcases/kernel/mem/tunable/overcommit_memory.c b/testcases/kernel/mem/tunable/overcommit_memory.c index 9b2cb479d..f9f60ebc3 100644 --- a/testcases/kernel/mem/tunable/overcommit_memory.c +++ b/testcases/kernel/mem/tunable/overcommit_memory.c @@ -68,6 +68,7 @@ #define DEFAULT_OVER_RATIO 50L #define EXPECT_PASS 0 #define EXPECT_FAIL 1 +#define ONE_GB (1024 * 1024 * TST_KB)

#define OVERCOMMIT_MEMORY "/proc/sys/vm/overcommit_memory" #define OVERCOMMIT_RATIO "/proc/sys/vm/overcommit_ratio" @@ -141,14 +142,26 @@ static void overcommit_memory_test(void)

update_mem(); alloc_and_check(free_total / 2, EXPECT_PASS); - alloc_and_check(sum_total * 2, EXPECT_FAIL); + /* Skip if sum_total * 2 would exceed address space. + * On 32-bit, skip when sum_total > ULONG_MAX/4 (~1GB). + * Most 32-bit systems with <=1GB RAM can map 2x that in 3GB vaddr space. + * Systems with 2GB+ RAM likely cannot fit allocations in vaddr space. */ + if (tst_kernel_bits() == 64 || (unsigned long)sum_total <= ONE_GB) { + alloc_and_check(sum_total * 2, EXPECT_FAIL); + } else { + tst_res(TCONF, "Skipping large allocation test due to address space limits"); + }

/* start to test overcommit_memory=1 */ TST_SYS_CONF_LONG_SET(OVERCOMMIT_MEMORY, 1, 1);

alloc_and_check(sum_total / 2, EXPECT_PASS); - alloc_and_check(sum_total, EXPECT_PASS); - alloc_and_check(sum_total * 2, EXPECT_PASS); + if (tst_kernel_bits() == 64 || (unsigned long)sum_total <= ONE_GB) { + alloc_and_check(sum_total, EXPECT_PASS); + alloc_and_check(sum_total * 2, EXPECT_PASS); + } else { + tst_res(TCONF, "Skipping large allocation tests due to address space limits"); + }

}