From: Lorenzo Stoakes (Oracle) Date: Tue, 31 Mar 2026 07:36:27 +0000 (+0100) Subject: tools/testing/selftests: add merge test for partial msealed range X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=84f4928446e65b9f3f142809f192edf46f67e380;p=thirdparty%2Fkernel%2Flinux.git tools/testing/selftests: add merge test for partial msealed range Commit 2697dd8ae721 ("mm/mseal: update VMA end correctly on merge") fixed an issue in the loop which iterates through VMAs applying mseal, which was triggered by mseal()'ing a range of VMAs where the second was mseal()'d and the first mergeable with it, once mseal()'d. Add a regression test to assert that this behaviour is correct. We place it in the merge selftests as this is strictly an issue with merging (via a vma_modify() invocation). It also asserts that mseal()'d ranges are correctly merged as you'd expect. The test is implemented such that it is skipped if mseal() is not available on the system. [rppt@kernel.org: fix inclusions, to fix handle_uprobe_upon_merged_vma()] Link: https://lore.kernel.org/ac_mCIUQWRAbuH8F@kernel.org [ljs@kernel.org: simplifications per Pedro] Link: https://lore.kernel.org/1c9c922d-5cb5-4cff-9273-b737cdb57ca1@lucifer.local Link: https://lore.kernel.org/20260331073627.50010-1-ljs@kernel.org Signed-off-by: Lorenzo Stoakes (Oracle) Signed-off-by: Mike Rapoport Cc: David Hildenbrand Cc: Jann Horn Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Pedro Falcato Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/mm/merge.c index 10b686102b79..519e5ac02db7 100644 --- a/tools/testing/selftests/mm/merge.c +++ b/tools/testing/selftests/mm/merge.c @@ -48,6 +48,19 @@ static pid_t do_fork(struct procmap_fd *procmap) return 0; } +#ifdef __NR_mseal +static int sys_mseal(void *ptr, size_t len, unsigned long flags) +{ + return syscall(__NR_mseal, (unsigned long)ptr, len, flags); +} +#else +static int sys_mseal(void *ptr, size_t len, unsigned long flags) +{ + errno = ENOSYS; + return -1; +} +#endif + FIXTURE_SETUP(merge) { self->page_size = psize(); @@ -1217,6 +1230,81 @@ TEST_F(merge, mremap_correct_placed_faulted) ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 15 * page_size); } +TEST_F(merge, merge_vmas_with_mseal) +{ + unsigned int page_size = self->page_size; + struct procmap_fd *procmap = &self->procmap; + char *ptr, *ptr2, *ptr3; + /* We need our own as cannot munmap() once sealed. */ + char *carveout; + + /* Invalid mseal() call to see if implemented. */ + ASSERT_EQ(sys_mseal(NULL, 0, ~0UL), -1); + if (errno == ENOSYS) + SKIP(return, "mseal not supported, skipping."); + + /* Map carveout. */ + carveout = mmap(NULL, 5 * page_size, PROT_NONE, + MAP_PRIVATE | MAP_ANON, -1, 0); + ASSERT_NE(carveout, MAP_FAILED); + + /* + * Map 3 separate VMAs: + * + * |-----------|-----------|-----------| + * | RW | RWE | RO | + * |-----------|-----------|-----------| + * ptr ptr2 ptr3 + */ + ptr = mmap(&carveout[page_size], page_size, PROT_READ | PROT_WRITE, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr, MAP_FAILED); + ptr2 = mmap(&carveout[2 * page_size], page_size, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr2, MAP_FAILED); + ptr3 = mmap(&carveout[3 * page_size], page_size, PROT_READ, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr3, MAP_FAILED); + + /* + * mseal the second VMA: + * + * |-----------|-----------|-----------| + * | RW | RWES | RO | + * |-----------|-----------|-----------| + * ptr ptr2 ptr3 + */ + ASSERT_EQ(sys_mseal(ptr2, page_size, 0), 0); + + /* Make first VMA mergeable upon mseal. */ + ASSERT_EQ(mprotect(ptr, page_size, + PROT_READ | PROT_WRITE | PROT_EXEC), 0); + /* + * At this point we have: + * + * |-----------|-----------|-----------| + * | RWE | RWES | RO | + * |-----------|-----------|-----------| + * ptr ptr2 ptr3 + * + * Now mseal all of the VMAs. + */ + ASSERT_EQ(sys_mseal(ptr, 3 * page_size, 0), 0); + + /* + * We should end up with: + * + * |-----------------------|-----------| + * | RWES | ROS | + * |-----------------------|-----------| + * ptr ptr3 + */ + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 2 * page_size); +} + TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev) { struct procmap_fd *procmap = &self->procmap;