From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D777323536A for ; Wed, 21 May 2025 08:07:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747814863; cv=none; b=F3ui0j2xf9dmqlDZSFBS780G3Y3HIII8jDLb2bVTh8JqIUBIIhFCISZlLsPDBmPz0zrP0KjVXCeqBQAxA8j+4SDIK0LNoxGS/LJTWrRjiP9a8qF63WVD/pMksK9Kb9v+Bq2ZBFokMZS8vhdBhWbsgOereDhAF102U48yzmlh/bg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747814863; c=relaxed/simple; bh=9Wu/5+pZRgvbXLVfxj0ht7kYsXhLJaM3KULAqCkCQFQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Rco1w4tUzbl3NWRX1Eiz67qht8DiNJsP3hSFokFi2Z4yj5eDIsDGns8LjmTEj5yXigsFkyeCwUXSLZyoMFUXh1bXresX64zsqrhXGIL7mJgkNXe9RHrfch0gdJ6RL5dohHM6rIImXy1OpOzNYdIrw++/OEgfhqBITFAK/wyXIQg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=E0hdLvQH; arc=none smtp.client-ip=91.218.175.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="E0hdLvQH" Message-ID: <34bd0faf-30b9-41f1-a768-0ed7165b4b98@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1747814858; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fEaKuSnjA40/mgx1OTc7sUEXciIH5kxDTRhEgaMMCXg=; b=E0hdLvQHY6k4outi1igGRNlJCmNjcYXgUyQwytoFhz0WUt5flz3q2OeoVUzsJH3N1iKjwV f7totfAZlNsEJNAoaPFVtFHgqBY24NB8UJ79uHxuT6dSAdoEBL7bQXeJNszZJfYiA8mhkG B4bUnoIFIwPsU6jbrBQahnTUVc+Xc2s= Date: Wed, 21 May 2025 16:07:29 +0800 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 4/4] tools/testing/selftests: add VMA merge tests for KSM merge To: Lorenzo Stoakes , Andrew Morton Cc: Alexander Viro , Christian Brauner , Jan Kara , "Liam R . 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 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