The patch titled
Subject: selftest/vm: verify mmap addr in mremap_test
has been added to the -mm tree. Its filename is
selftest-vm-verify-mmap-addr-in-mremap_test.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/selftest-vm-verify-mmap-addr-in-mremap_test.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/selftest-vm-verify-mmap-addr-in-mremap_test.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Subject: selftest/vm: verify mmap addr in mremap_test
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.
Link: https://lkml.kernel.org/r/20220420215721.4868-1-sidhartha.kumar@xxxxxxxxxx
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/vm/mremap_test.c | 41 ++++++++++++++++++++-
1 file changed, 40 insertions(+), 1 deletion(-)
--- a/tools/testing/selftests/vm/mremap_test.c~selftest-vm-verify-mmap-addr-in-mremap_test
+++ a/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>
@@ -63,6 +64,35 @@ 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.
@@ -71,8 +101,15 @@ static void *get_source_mapping(struct 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);
@@ -90,8 +127,10 @@ retry:
* 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;
_
Patches currently in -mm which might be from sidhartha.kumar@xxxxxxxxxx are
selftest-vm-verify-mmap-addr-in-mremap_test.patch
selftest-vm-verify-remap-destination-address-in-mremap_test.patch
selftest-vm-support-xfail-in-mremap_test.patch
selftest-vm-add-skip-support-to-mremap_test.patch
selftest-vm-clarify-error-statement-in-gup_test.patch
