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Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , David Hildenbrand , Xu Xin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <95db1783c752fd4032fc0e81431afe7e6d128630.1747431920.git.lorenzo.stoakes@oracle.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: <95db1783c752fd4032fc0e81431afe7e6d128630.1747431920.git.lorenzo.stoakes@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam10 X-Stat-Signature: dqok9z5ixg1ay38pcfqapbf8q9do1bcz X-Rspamd-Queue-Id: 0EAD340006 X-Rspam-User: X-HE-Tag: 1747814860-351923 X-HE-Meta: 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 5lDbFArw ZggrqqyHi8StuIJbC5uoZCPlT0iSilA/SkvGUyx3r/qPzvgzf+SrLbSiY0ziWD4uwFs5mjnVROsYM51QHNOnJUBCQJPP75xQb2PXKLg9RNEAj1WjGyRXDmI8U31+MgiGCh5C79bLtyH9G8wY7RjvmrTPj34W8amkBX/do9ZIfzj3dgV11zieyoANKy4esSAdkm+EaLtEkGm0cPL1eAs8axtvdfeztOKOZJwc26insCWlHR2uir+PN8yZiuMPtsawmn8USSXADp/mN/52t97HOgJ7AFA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/5/19 16:51, Lorenzo Stoakes wrote: > Add test to assert that we have now allowed merging of VMAs when KSM > merging-by-default has been set by prctl(PR_SET_MEMORY_MERGE, ...). > > We simply perform a trivial mapping of adjacent VMAs expecting a merge, > however prior to recent changes implementing this mode earlier than before, > these merges would not have succeeded. > > Assert that we have fixed this! > > Signed-off-by: Lorenzo Stoakes Reviewed-by: Chengming Zhou Tested-by: Chengming Zhou Thanks! > --- > tools/testing/selftests/mm/merge.c | 78 ++++++++++++++++++++++++++++++ > 1 file changed, 78 insertions(+) > > diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/mm/merge.c > index c76646cdf6e6..2380a5a6a529 100644 > --- a/tools/testing/selftests/mm/merge.c > +++ b/tools/testing/selftests/mm/merge.c > @@ -2,10 +2,12 @@ > > #define _GNU_SOURCE > #include "../kselftest_harness.h" > +#include > #include > #include > #include > #include > +#include > #include > #include "vm_util.h" > > @@ -31,6 +33,11 @@ FIXTURE_TEARDOWN(merge) > { > ASSERT_EQ(munmap(self->carveout, 12 * self->page_size), 0); > ASSERT_EQ(close_procmap(&self->procmap), 0); > + /* > + * Clear unconditionally, as some tests set this. It is no issue if this > + * fails (KSM may be disabled for instance). > + */ > + prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0); > } > > TEST_F(merge, mprotect_unfaulted_left) > @@ -452,4 +459,75 @@ TEST_F(merge, forked_source_vma) > ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr2 + 5 * page_size); > } > > +TEST_F(merge, ksm_merge) > +{ > + unsigned int page_size = self->page_size; > + char *carveout = self->carveout; > + struct procmap_fd *procmap = &self->procmap; > + char *ptr, *ptr2; > + int err; > + > + /* > + * Map two R/W immediately adjacent to one another, they should > + * trivially merge: > + * > + * |-----------|-----------| > + * | R/W | R/W | > + * |-----------|-----------| > + * ptr ptr2 > + */ > + > + 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, > + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); > + ASSERT_NE(ptr2, MAP_FAILED); > + 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); > + > + /* Unmap the second half of this merged VMA. */ > + ASSERT_EQ(munmap(ptr2, page_size), 0); > + > + /* OK, now enable global KSM merge. We clear this on test teardown. */ > + err = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0); > + if (err == -1) { > + int errnum = errno; > + > + /* Only non-failure case... */ > + ASSERT_EQ(errnum, EINVAL); > + /* ...but indicates we should skip. */ > + SKIP(return, "KSM memory merging not supported, skipping."); > + } > + > + /* > + * Now map a VMA adjacent to the existing that was just made > + * VM_MERGEABLE, this should merge as well. > + */ > + ptr2 = mmap(&carveout[2 * page_size], page_size, > + PROT_READ | PROT_WRITE, > + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); > + ASSERT_NE(ptr2, MAP_FAILED); > + 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); > + > + /* Now this VMA altogether. */ > + ASSERT_EQ(munmap(ptr, 2 * page_size), 0); > + > + /* Try the same operation as before, asserting this also merges fine. */ > + 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, > + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); > + ASSERT_NE(ptr2, MAP_FAILED); > + 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_HARNESS_MAIN