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Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , David Hildenbrand , 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: References: <20260331073627.50010-1-ljs@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260331073627.50010-1-ljs@kernel.org> X-Rspamd-Queue-Id: 521A81C000E X-Stat-Signature: 5i3drr3rmcx5xeo4d5beh9dhpmkdn6ts X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1775232528-449448 X-HE-Meta: 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 88m71BS8 7otvTo+dlNQe4gKZxnOMfvUQkwDKQsbD6qesl8zN663exx+0XTpNBk2J/ouYusmxKmOAamskOTxf/Swy5LcaqyoVlidcJT7WVscRrgyDfHwEpAdN+RdAuYMj1Luj4hK8lehlTEAOVr0SOEhvP6cw8B3elqWbDauAEhVBgpjZ85mynz/JF67KZyakhtga4bCX4iicrNjqEZwbLYI6ySIE7SGvDqi0XUPoY0GqDc1O/dpQ5WbnwVkHIkoZZSkU6xF0DtxVhOqMO/FyZ3AYKs4Vs9NHCfKQaZaCq7sj1KWaGmcpxomlcKeI6HydIqw== 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 08:36:27AM +0100, Lorenzo Stoakes (Oracle) wrote: > 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 assert 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. > > Signed-off-by: Lorenzo Stoakes (Oracle) > --- > v2: > * Added tools/ based header so __NR_mseal should always be available. > * However, for completeness, also check to see if defined, and assume ENOSYS if > not. > * Thanks to Mike for reporting issues in his build on this test! Unfortunately it's not the only one :) The header inclusion actually causes handle_uprobe_upon_merged_vma() to fail because of mismatch in definition of__NR_perf_event_open in and the correct definition from /usr/include/unistd.h With the patch below handle_uprobe_upon_merged_vma() passes again and I think it's not needed for mseal tests as well. diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/mm/merge.c index efcb100fd865..519e5ac02db7 100644 --- a/tools/testing/selftests/mm/merge.c +++ b/tools/testing/selftests/mm/merge.c @@ -2,7 +2,6 @@ #define _GNU_SOURCE #include "kselftest_harness.h" -#include #include #include #include > v1: > https://lore.kernel.org/all/20260330135011.107036-1-ljs@kernel.org/ > > tools/testing/selftests/mm/merge.c | 89 ++++++++++++++++++++++++++++++ > 1 file changed, 89 insertions(+) > > diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/mm/merge.c > index 10b686102b79..f73803b3679a 100644 > --- a/tools/testing/selftests/mm/merge.c > +++ b/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 *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 +1231,81 @@ 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, 17 * 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], 5 * page_size, PROT_READ | PROT_WRITE, > + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); > + ASSERT_NE(ptr, MAP_FAILED); > + ptr2 = mmap(&carveout[page_size * 6], 5 * page_size, > + PROT_READ | PROT_WRITE | PROT_EXEC, > + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); > + ASSERT_NE(ptr2, MAP_FAILED); > + ptr3 = mmap(&carveout[page_size * 11], 5 * 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, 5 * page_size, 0), 0); > + > + /* Make first VMA mergeable upon mseal. */ > + ASSERT_EQ(mprotect(ptr, 5 * 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, 15 * 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 + 10 * page_size); > +} > + > TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev) > { > struct procmap_fd *procmap = &self->procmap; > -- > 2.53.0 > -- Sincerely yours, Mike.