On 28.10.25 22:24, Kalesh Singh wrote:
Add a new selftest to verify that the max VMA count limit is correctly
enforced.
This test suite checks that various VMA operations (mmap, mprotect,
munmap, mremap) succeed or fail as expected when the number of VMAs is
close to the sysctl_max_map_count limit.
The test works by first creating a large number of VMAs to bring the
process close to the limit, and then performing various operations that
may or may not create new VMAs. The test then verifies that the
operations that would exceed the limit fail, and that the operations
that do not exceed the limit succeed.
NOTE: munmap is special as it's allowed to temporarily exceed the limit
by one for splits as this will decrease back to the limit once the unmap
succeeds.
Cc: Andrew Morton <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: "Liam R. Howlett" <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Pedro Falcato <[email protected]>
Signed-off-by: Kalesh Singh <[email protected]>
---
[...]
No capacity to review the tests in detail :(
+
diff --git a/tools/testing/selftests/mm/run_vmtests.sh
b/tools/testing/selftests/mm/run_vmtests.sh
index d9173f2312b7..a85db61e6a92 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -49,6 +49,8 @@ separated by spaces:
test madvise(2) MADV_GUARD_INSTALL and MADV_GUARD_REMOVE options
- madv_populate
test memadvise(2) MADV_POPULATE_{READ,WRITE} options
+- max_vma_count
+ tests for max vma_count
- memfd_secret
test memfd_secret(2)
- process_mrelease
@@ -426,6 +428,9 @@ fi # VADDR64
# vmalloc stability smoke test
CATEGORY="vmalloc" run_test bash ./test_vmalloc.sh smoke
+# test operations against max vma count limit
+CATEGORY="max_vma_count" run_test ./max_vma_count_tests
I'd just call it CATEGORY="vma" or "vma_handling".
Which makes me wodnering whether "vma_merge" falls into the same category.
Smalls like mremap test is similar.
Point is that "CATEGORY" stops being really useful if we end up having a
separate category for each test, right? :)
--
Cheers
David
