The patch titled
Subject: selftests/mm: virtual_address_range: unmap chunks after validation
has been added to the -mm mm-unstable branch. Its filename is
selftests-mm-virtual_address_range-unmap-chunks-after-validation.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-virtual_address_range-unmap-chunks-after-validation.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Thomas WeiÃ?schuh <thomas.weissschuh@xxxxxxxxxxxxx>
Subject: selftests/mm: virtual_address_range: unmap chunks after validation
Date: Mon, 13 Jan 2025 14:15:36 +0100
For each accessed chunk a PTE is created. More than 1GiB of PTEs is used
in this way. Remove each PTE after validating a chunk to reduce peak
memory usage.
It is important to only unmap memory that previously mmap()ed, as
unmapping other mappings like the stack, heap or executable mappings will
crash the process.
The mappings read from /proc/self/maps and the return values from mmap()
don't allow a simple correlation due to merging and no guaranteed order.
To correlate the pointers and mappings use prctl(PR_SET_VMA_ANON_NAME).
While it introduces a test dependency, other alternatives would introduce
runtime or development overhead.
Link: https://lkml.kernel.org/r/20250113-virtual_address_range-tests-v3-2-f4a8e6b7feed@xxxxxxxxxxxxx
Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()")
Signed-off-by: Thomas WeiÃ?schuh <thomas.weissschuh@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Dev Jain <dev.jain@xxxxxxx>
Cc: kernel test robot <oliver.sang@xxxxxxxxx>
Cc: Shuah Khan (Samsung OSG) <shuah@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/mm/config | 1
tools/testing/selftests/mm/virtual_address_range.c | 33 ++++++++++-
2 files changed, 32 insertions(+), 2 deletions(-)
--- a/tools/testing/selftests/mm/config~selftests-mm-virtual_address_range-unmap-chunks-after-validation
+++ a/tools/testing/selftests/mm/config
@@ -7,3 +7,4 @@ CONFIG_TEST_HMM=m
CONFIG_GUP_TEST=y
CONFIG_TRANSPARENT_HUGEPAGE=y
CONFIG_MEM_SOFT_DIRTY=y
+CONFIG_ANON_VMA_NAME=y
--- a/tools/testing/selftests/mm/virtual_address_range.c~selftests-mm-virtual_address_range-unmap-chunks-after-validation
+++ a/tools/testing/selftests/mm/virtual_address_range.c
@@ -10,6 +10,7 @@
#include <string.h>
#include <unistd.h>
#include <errno.h>
+#include <sys/prctl.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <fcntl.h>
@@ -82,6 +83,24 @@ static void validate_addr(char *ptr, int
ksft_exit_fail_msg("Bad address %lx\n", addr);
}
+static void mark_range(char *ptr, size_t size)
+{
+ if (prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, size, "virtual_address_range") == -1) {
+ if (errno == EINVAL) {
+ /* Depends on CONFIG_ANON_VMA_NAME */
+ ksft_test_result_skip("prctl(PR_SET_VMA_ANON_NAME) not supported\n");
+ ksft_finished();
+ } else {
+ ksft_exit_fail_perror("prctl(PR_SET_VMA_ANON_NAME) failed\n");
+ }
+ }
+}
+
+static int is_marked_vma(const char *vma_name)
+{
+ return vma_name && !strcmp(vma_name, "[anon:virtual_address_range]\n");
+}
+
static int validate_lower_address_hint(void)
{
char *ptr;
@@ -116,12 +135,17 @@ static int validate_complete_va_space(vo
prev_end_addr = 0;
while (fgets(line, sizeof(line), file)) {
+ const char *vma_name = NULL;
+ int vma_name_start = 0;
unsigned long hop;
- if (sscanf(line, "%lx-%lx %s[rwxp-]",
- &start_addr, &end_addr, prot) != 3)
+ if (sscanf(line, "%lx-%lx %4s %*s %*s %*s %n",
+ &start_addr, &end_addr, prot, &vma_name_start) != 3)
ksft_exit_fail_msg("cannot parse /proc/self/maps\n");
+ if (vma_name_start)
+ vma_name = line + vma_name_start;
+
/* end of userspace mappings; ignore vsyscall mapping */
if (start_addr & (1UL << 63))
return 0;
@@ -149,6 +173,9 @@ static int validate_complete_va_space(vo
return 1;
lseek(fd, 0, SEEK_SET);
+ if (is_marked_vma(vma_name))
+ munmap((char *)(start_addr + hop), MAP_CHUNK_SIZE);
+
hop += MAP_CHUNK_SIZE;
}
}
@@ -175,6 +202,7 @@ int main(void)
break;
}
+ mark_range(ptr[i], MAP_CHUNK_SIZE);
validate_addr(ptr[i], 0);
}
lchunks = i;
@@ -192,6 +220,7 @@ int main(void)
if (hptr[i] == MAP_FAILED)
break;
+ mark_range(ptr[i], MAP_CHUNK_SIZE);
validate_addr(hptr[i], 1);
}
hchunks = i;
_
Patches currently in -mm which might be from thomas.weissschuh@xxxxxxxxxxxxx are
selftests-mm-virtual_address_range-mmap-without-prot_write.patch
selftests-mm-virtual_address_range-unmap-chunks-after-validation.patch
selftests-mm-vm_util-split-up-proc-self-smaps-parsing.patch
selftests-mm-virtual_address_range-avoid-reading-from-vm_io-mappings.patch
