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Howlett" , Vlastimil Babka , Jann Horn , David Hildenbrand , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] tools/testing/selftests: add merge test for partial msealed range Message-ID: <2b2eb985-ecf9-4477-a967-872153199dcf@lucifer.local> References: <20260331073627.50010-1-ljs@kernel.org> <1c9c922d-5cb5-4cff-9273-b737cdb57ca1@lucifer.local> <20260331175851.91867c426e09a5b3eccc1d6f@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260331175851.91867c426e09a5b3eccc1d6f@linux-foundation.org> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 3EB034000A X-Stat-Signature: nw6oygaziks8pjso9yd9cmmgwigzmg9y X-Rspam-User: X-HE-Tag: 1775032328-497311 X-HE-Meta: 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 VGaYnVIl X2J+yRfCQGEZT7lF34+tzUaV/JWvD/P9JMWLKX5DPZjYRaesRUN0tBRgk6YtQD3yMgC0xdEONLVi2zJtGUf7RhhNH7MPsdu0iRA/gdTZArEtNSzthvfIJ99IV+uLzFmS2SwqsNLgmY4gXDxeB3N8T8NBNmU5ka1WiTaKQN7BZk6VqpilBQTUQlXJCWpinndzTaIc2OuztfdRDtJPMUWrNMCdtnOZvjobdNQUCdO7QOyHAgNzHvCQ0r9kEY3QN6H/SRKtYf3xoyxEW07ckm+iaUMQGzE98puj1TWgjzuDredY6UtT+OH2gszbVt2yBII70f+TZPlFqZbF2Y8NRha9XdyIJQ2Ld4UfUxJ2Q/rdWnqMJEZFuR3BIwE+6uPRw7sLHAK+QbUqhYRfn1Z1DkqQWmpqV3Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 31, 2026 at 05:58:51PM -0700, Andrew Morton wrote: > On Tue, 31 Mar 2026 11:08:03 +0100 "Lorenzo Stoakes (Oracle)" wrote: > > > Then again, and contradicting myself elsewhere on fix-patches blah blah blah, > > since this is just test code, I checked the below and it works the same and > > triggers the regression. > > > > So maybe we can just apply that? > > Here's how the two folded together will look: Thanks, LGTM! Cheers, Lorenzo > > > From: "Lorenzo Stoakes (Oracle)" > Subject: tools/testing/selftests: add merge test for partial msealed range > Date: Tue, 31 Mar 2026 08:36:27 +0100 > > 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. > > [ljs@kernel.org: simplifications per Pedro] > Link: https://lkml.kernel.org/r/1c9c922d-5cb5-4cff-9273-b737cdb57ca1@lucifer.local > Link: https://lkml.kernel.org/r/20260331073627.50010-1-ljs@kernel.org > Signed-off-by: Lorenzo Stoakes (Oracle) > Cc: David Hildenbrand > Cc: Jann Horn > Cc: Liam Howlett > Cc: Lorenzo Stoakes > Cc: Michal Hocko > Cc: Mike Rapoport > Cc: Pedro Falcato > Cc: Shuah Khan > Cc: Suren Baghdasaryan > Cc: Vlastimil Babka > Signed-off-by: Andrew Morton > --- > > tools/testing/selftests/mm/merge.c | 89 +++++++++++++++++++++++++++ > 1 file changed, 89 insertions(+) > > --- a/tools/testing/selftests/mm/merge.c~tools-testing-selftests-add-merge-test-for-partial-msealed-range > +++ a/tools/testing/selftests/mm/merge.c > @@ -2,6 +2,7 @@ > > #define _GNU_SOURCE > #include "kselftest_harness.h" > +#include > #include > #include > #include > @@ -48,6 +49,19 @@ static pid_t do_fork(struct procmap_fd * > 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 +1231,81 @@ TEST_F(merge, mremap_correct_placed_faul > 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; > _ >