From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f200.google.com (mail-qt0-f200.google.com [209.85.216.200]) by kanga.kvack.org (Postfix) with ESMTP id 9861C6B025F for ; Thu, 20 Jul 2017 19:19:50 -0400 (EDT) Received: by mail-qt0-f200.google.com with SMTP id n43so24888111qtc.13 for ; Thu, 20 Jul 2017 16:19:50 -0700 (PDT) Received: from aserp1040.oracle.com (aserp1040.oracle.com. [141.146.126.69]) by mx.google.com with ESMTPS id z60si2684430qtc.86.2017.07.20.16.19.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 20 Jul 2017 16:19:49 -0700 (PDT) Subject: Re: [PATCH] selftests/vm: Add test to validate mirror functionality with mremap References: <20170720093651.22106-1-khandual@linux.vnet.ibm.com> From: Mike Kravetz Message-ID: <965cf169-572c-537b-6784-766edcb4eb19@oracle.com> Date: Thu, 20 Jul 2017 16:19:31 -0700 MIME-Version: 1.0 In-Reply-To: <20170720093651.22106-1-khandual@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Anshuman Khandual , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org On 07/20/2017 02:36 AM, Anshuman Khandual wrote: > This adds a test to validate mirror functionality with mremap() > system call on shared anon mappings. > > Suggested-by: Mike Kravetz > Signed-off-by: Anshuman Khandual > --- > tools/testing/selftests/vm/Makefile | 1 + > .../selftests/vm/mremap_mirror_shared_anon.c | 54 ++++++++++++++++++++++ This may be a better fit in LTP where there are already several other mremap tests. I honestly do not know the best place for such a test. > 2 files changed, 55 insertions(+) > create mode 100644 tools/testing/selftests/vm/mremap_mirror_shared_anon.c > > diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile > index cbb29e4..11657ff5 100644 > --- a/tools/testing/selftests/vm/Makefile > +++ b/tools/testing/selftests/vm/Makefile > @@ -17,6 +17,7 @@ TEST_GEN_FILES += transhuge-stress > TEST_GEN_FILES += userfaultfd > TEST_GEN_FILES += mlock-random-test > TEST_GEN_FILES += virtual_address_range > +TEST_GEN_FILES += mremap_mirror_shared_anon > > TEST_PROGS := run_vmtests > > diff --git a/tools/testing/selftests/vm/mremap_mirror_shared_anon.c b/tools/testing/selftests/vm/mremap_mirror_shared_anon.c > new file mode 100644 > index 0000000..b0adbb2 > --- /dev/null > +++ b/tools/testing/selftests/vm/mremap_mirror_shared_anon.c > @@ -0,0 +1,54 @@ > +/* > + * Test to verify mirror functionality with mremap() system > + * call for shared anon mappings. > + * > + * Copyright (C) 2017 Anshuman Khandual, IBM Corporation > + * > + * Licensed under GPL V2 > + */ > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define PATTERN 0xbe > +#define ALLOC_SIZE 0x10000UL /* Works for 64K and 4K pages */ Why hardcode? You could use sysconf to get page size and use some multiple of that. > + > +int test_mirror(char *old, char *new, unsigned long size) > +{ > + unsigned long i; > + > + for (i = 0; i < size; i++) { > + if (new[i] != old[i]) { > + printf("Mismatch at new[%lu] expected " > + "%d received %d\n", i, old[i], new[i]); > + return 1; > + } > + } > + return 0; > +} > + > +int main(int argc, char *argv[]) > +{ > + char *ptr, *mirror_ptr; > + > + ptr = mmap(NULL, ALLOC_SIZE, PROT_READ | PROT_WRITE, > + MAP_SHARED | MAP_ANONYMOUS, -1, 0); > + if (ptr == MAP_FAILED) { > + perror("map() failed"); > + return -1; > + } > + memset(ptr, PATTERN, ALLOC_SIZE); > + > + mirror_ptr = (char *) mremap(ptr, 0, ALLOC_SIZE, 1); Why hardcode 1? You really want the MREMAP_MAYMOVE flag. Right? > + if (mirror_ptr == MAP_FAILED) { > + perror("mremap() failed"); > + return -1; > + } > + > + if (test_mirror(ptr, mirror_ptr, ALLOC_SIZE)) > + return 1; > + return 0; > +} You may want to expand the test to make sure mremap(old_size == 0) fails for private mappings. Of course, this assumes my proposed patch gets in. Until then, it will succeed and create a new unrelated mapping. -- Mike Kravetz -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org