From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 D0578275870 for ; Thu, 17 Sep 2026 05:37:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789623480; cv=none; b=iNh/UNRHLNXt78Go+nKfT+9zVpXfSVyFI+V1Uf8Ou+9jWB88Ex7rVIehuhPMs5IH//NMJMEwsLz54ZUnew5pwrP+IE+IRDOTicRQ0XmVlxNrzSDpx7VFUMRLahEnZtAKsUfgh/lfxmAUrey/dPfOOP+wxEkeiCBCxoNFdOHhvB0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789623480; c=relaxed/simple; bh=PWH9dmYd58JIAqpcVg+cnbL2DO2qVuJO1sJbEcYlP5w=; h=Date:To:From:Subject:Message-Id; b=HezkerVJcuJuo3Exhj3GizTg8pbq6PwiYUaBBy3G70Ba55ZnvmcBa926kzx4+ooTrL5Al9xGPoLA45DP7XgbdFGLQtJ5I+sA+f4ne7SrY7kV3jqg9RYyRZDlSsfrOFGUWG8HUTEMRU4jVEOGzPVnUqWQ/2DpJdwEOSo6VYSuJlg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=Nyaywn1T; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="Nyaywn1T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 827CF1F00893; Thu, 17 Sep 2026 05:37:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789623478; bh=mPCpEv0qmZw2SS+2Md5MBmgpTlUOSephiA3dcn3PjyA=; h=Date:To:From:Subject; b=Nyaywn1Th7SiZ74qsR/ovbrD53tpMSovJiFp1aPJXuCA3I7TmExz0bDRbuVymSrUf vDhEaVvYbukeIAqNLOa0O7w8uPtYE6+mNZRrzynL+R/Ejv9/VMPC8yCfsxbszEVwJq wn6QWMF9I8M2QflbQYLNyvZBpVfrZ22UjotnG3x4= Date: Wed, 16 Sep 2026 22:37:58 -0700 To: mm-commits@vger.kernel.org,zokeefe@google.com,ziy@nvidia.com,shy828301@gmail.com,ryan.roberts@arm.com,ljs@kernel.org,liam@infradead.org,lance.yang@linux.dev,kas@kernel.org,hughd@google.com,dev.jain@arm.com,david@kernel.org,baolin.wang@linux.alibaba.com,baohua@kernel.org,jthoughton@google.com,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] mm-selftests-adjust-the-madv_collapse-uffd-minor-selftests.patch removed from -mm tree Message-Id: <20260917053758.827CF1F00893@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: selftests: adjust the MADV_COLLAPSE uffd-minor selftests has been removed from the -mm tree. Its filename was mm-selftests-adjust-the-madv_collapse-uffd-minor-selftests.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: James Houghton Subject: mm: selftests: adjust the MADV_COLLAPSE uffd-minor selftests Date: Thu, 10 Sep 2026 02:34:11 +0000 The behavior of MADV_COLLAPSE with uffd-minor VMAs has changed: MADV_COLLAPSE will no longer install PTEs where none existed before. Update the selftest to demonstrate this new behavior. On an unpatched kernel, the test will hit "unexpected memory contents after collapse". If the selftest is left unpatched but the kernel is patched, the selftest will SKIP when it gets EINVAL back from MADV_COLLAPSE. Link: https://lore.kernel.org/20260910023411.514987-2-jthoughton@google.com Signed-off-by: James Houghton Signed-off-by: Andrew Morton Cc: Baolin Wang Cc: Barry Song Cc: David Hildenbrand Cc: Dev Jain Cc: Hugh Dickins Cc: Kiryl Shutsemau Cc: Lance Yang Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Ryan Roberts Cc: Yang Shi Cc: Zach O'Keefe Cc: Zi Yan --- tools/testing/selftests/mm/uffd-unit-tests.c | 75 +++++++++++++++-- 1 file changed, 68 insertions(+), 7 deletions(-) --- a/tools/testing/selftests/mm/uffd-unit-tests.c~mm-selftests-adjust-the-madv_collapse-uffd-minor-selftests +++ a/tools/testing/selftests/mm/uffd-unit-tests.c @@ -518,19 +518,34 @@ static void uffd_wp_fork_pin_with_event_ uffd_wp_fork_pin_test_common(gopts, args, true); } -static void check_memory_contents(uffd_global_test_opts_t *gopts, char *p) +static int __check_memory_contents(unsigned long offset, + unsigned long nr_pages, + uffd_global_test_opts_t *gopts, + char *p) { unsigned long i, j; uint8_t expected_byte; - for (i = 0; i < gopts->nr_pages; ++i) { + if (nr_pages + offset < nr_pages) + err("overflow in memory check"); + if (nr_pages + offset > gopts->nr_pages) + err("out of bounds memory check"); + + for (i = offset; i < offset + nr_pages; ++i) { expected_byte = ~((uint8_t)(i % ((uint8_t)-1))); for (j = 0; j < gopts->page_size; j++) { uint8_t v = *(uint8_t *)(p + (i * gopts->page_size) + j); if (v != expected_byte) - err("unexpected page contents"); + return 1; } } + + return 0; +} + +static int check_memory_contents(uffd_global_test_opts_t *gopts, char *p) +{ + return __check_memory_contents(0, gopts->nr_pages, gopts, p); } static void uffd_minor_test_common(uffd_global_test_opts_t *gopts, bool test_collapse, bool test_wp) @@ -539,6 +554,8 @@ static void uffd_minor_test_common(uffd_ pthread_t uffd_mon; char c = '\0'; struct uffd_args args = { 0 }; + unsigned long checked = 0; + bool bad_contents; args.gopts = gopts; /* @@ -564,24 +581,65 @@ static void uffd_minor_test_common(uffd_ if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args)) err("uffd_poll_thread create"); + if (test_collapse) { + /* + * Read just a single page and try collapsing. The collapse + * should either be rejected or be a no-op. + */ + if (__check_memory_contents(0, 1, gopts, gopts->area_dst_alias)) + err("unexpected memory contents before collapse"); + + /* MADV_COLLAPSE might return EINVAL for uffd-minor VMAs. */ + madvise(gopts->area_dst_alias, gopts->nr_pages * gopts->page_size, + MADV_COLLAPSE); + /* + * If the above collapse mapped pages that were not explicitly + * CONTINUE'd, the below __check_memory_contents() will not + * fault on some pages, resulting in incorrect contents. The + * PTE for the first page may get retracted, so avoid checking + * that page, as we might take a second fault, flipping the + * contents a second time. + */ + checked = 1; + } + /* * Read each of the pages back using the UFFD-registered mapping. We * expect that the first time we touch a page, it will result in a minor * fault. uffd_poll_thread will resolve the fault by bit-flipping the * page's contents, and then issuing a CONTINUE ioctl. */ - check_memory_contents(gopts, gopts->area_dst_alias); + bad_contents = !!__check_memory_contents(checked, gopts->nr_pages - checked, + gopts, gopts->area_dst_alias); if (write(gopts->pipefd[1], &c, sizeof(c)) != sizeof(c)) err("pipe write"); if (pthread_join(uffd_mon, NULL)) err("join() failed"); + if (bad_contents && test_collapse) { + uffd_test_fail("unexpected memory contents after collapse"); + return; + } + + if (bad_contents) { + uffd_test_fail("unexpected memory contents"); + return; + } + if (test_collapse) { + /* + * MADV_COLLAPSE will fail unless userfaultfd-minor is + * unregistered. + */ + if (uffd_unregister(gopts->uffd, gopts->area_dst_alias, + gopts->nr_pages * gopts->page_size)) + err("uffd_unregister before MADV_COLLAPSE failed"); + + /* MADV_COLLAPSE should succeed with userfaultfd unregistered. */ if (madvise(gopts->area_dst_alias, gopts->nr_pages * gopts->page_size, MADV_COLLAPSE)) { - /* It's fine to fail for this one... */ - uffd_test_skip("MADV_COLLAPSE failed"); + uffd_test_fail("MADV_COLLAPSE failed"); return; } @@ -593,7 +651,10 @@ static void uffd_minor_test_common(uffd_ * This won't cause uffd-fault - it purely just makes sure there * was no corruption. */ - check_memory_contents(gopts, gopts->area_dst_alias); + if (check_memory_contents(gopts, gopts->area_dst_alias)) { + uffd_test_fail("unexpected memory contents"); + return; + } } if (args.missing_faults != 0 || args.minor_faults != gopts->nr_pages) _ Patches currently in -mm which might be from jthoughton@google.com are