Avoid calling mmap with requested addresses that are less than the system's
mmap_min_addr. When run as root, mmap returns EACCES when trying to map
addresses < mmap_min_addr. This is not one of the error codes for the
condition to retry the mmap in the test. Rather than arbitrarily retrying
on EACCES, don't attempt an mmap until addr > vm.mmap_min_addr.
Add a munmap call after an alignment check as the mappings are retained
after the retry and can reach the vm.max_map_count sysctl.
Signed-off-by: Sidhartha Kumar <[email protected]>
---
v2:
-change comment for description of get_mmap_min_addr()
-fix commit message formatting
tools/testing/selftests/vm/mremap_test.c | 41 +++++++++++++++++++++++-
1 file changed, 40 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c
index 0624d1bd71b5..2b3b4f15185f 100644
--- a/tools/testing/selftests/vm/mremap_test.c
+++ b/tools/testing/selftests/vm/mremap_test.c
@@ -6,6 +6,7 @@
#include <errno.h>
#include <stdlib.h>
+#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <time.h>
@@ -64,6 +65,35 @@ enum {
.expect_failure = should_fail \
}
+/* Returns mmap_min_addr sysctl tunable from procfs */
+static unsigned long long get_mmap_min_addr(void)
+{
+ FILE *fp;
+ int n_matched;
+ static unsigned long long addr;
+
+ if (addr)
+ return addr;
+
+ fp = fopen("/proc/sys/vm/mmap_min_addr", "r");
+ if (fp == NULL) {
+ ksft_print_msg("Failed to open /proc/sys/vm/mmap_min_addr: %s\n",
+ strerror(errno));
+ exit(KSFT_SKIP);
+ }
+
+ n_matched = fscanf(fp, "%llu", &addr);
+ if (n_matched != 1) {
+ ksft_print_msg("Failed to read /proc/sys/vm/mmap_min_addr: %s\n",
+ strerror(errno));
+ fclose(fp);
+ exit(KSFT_SKIP);
+ }
+
+ fclose(fp);
+ return addr;
+}
+
/*
* Returns the start address of the mapping on success, else returns
* NULL on failure.
@@ -72,8 +102,15 @@ static void *get_source_mapping(struct config c)
{
unsigned long long addr = 0ULL;
void *src_addr = NULL;
+ unsigned long long mmap_min_addr;
+
+ mmap_min_addr = get_mmap_min_addr();
+
retry:
addr += c.src_alignment;
+ if (addr < mmap_min_addr)
+ goto retry;
+
src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE,
MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
-1, 0);
@@ -91,8 +128,10 @@ static void *get_source_mapping(struct config c)
* alignment in the tests.
*/
if (((unsigned long long) src_addr & (c.src_alignment - 1)) ||
- !((unsigned long long) src_addr & c.src_alignment))
+ !((unsigned long long) src_addr & c.src_alignment)) {
+ munmap(src_addr, c.region_size);
goto retry;
+ }
if (!src_addr)
goto error;
--
2.27.0
On 4/20/22 3:57 PM, Sidhartha Kumar wrote:
> Avoid calling mmap with requested addresses that are less than the system's
> mmap_min_addr. When run as root, mmap returns EACCES when trying to map
> addresses < mmap_min_addr. This is not one of the error codes for the
> condition to retry the mmap in the test. Rather than arbitrarily retrying
> on EACCES, don't attempt an mmap until addr > vm.mmap_min_addr.
>
> Add a munmap call after an alignment check as the mappings are retained
> after the retry and can reach the vm.max_map_count sysctl.
>
> Signed-off-by: Sidhartha Kumar <[email protected]>
> ---
> v2:
> -change comment for description of get_mmap_min_addr()
> -fix commit message formatting
>
Thank you.
Reviewed-by: Shuah Khan <[email protected]>
Andrew, please let me know if you would like me to take this
through kselftest tree.
thanks,
-- Shuah
Allow the mremap test to be skipped due to errors such as failing to parse
the mmap_min_addr sysctl.
Signed-off-by: Sidhartha Kumar <[email protected]>
Reviewed-by: Shuah Khan <[email protected]>
---
v2:
-add Reviewed-by tag
-fix commit message formatting
tools/testing/selftests/vm/run_vmtests.sh | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
index 88e15fbb5027..eae98f5de2cc 100755
--- a/tools/testing/selftests/vm/run_vmtests.sh
+++ b/tools/testing/selftests/vm/run_vmtests.sh
@@ -272,11 +272,16 @@ echo "-------------------"
echo "running mremap_test"
echo "-------------------"
./mremap_test
-if [ $? -ne 0 ]; then
+ret_val=$?
+
+if [ $ret_val -eq 0 ]; then
+ echo "[PASS]"
+elif [ $ret_val -eq $ksft_skip ]; then
+ echo "[SKIP]"
+ exitcode=$ksft_skip
+else
echo "[FAIL]"
exitcode=1
-else
- echo "[PASS]"
fi
echo "-----------------"
--
2.27.0