From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4B6361E1C11; Mon, 21 Oct 2024 10:28:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729506501; cv=none; b=fvoJU8ZzFSVCWzO+Ok0RWXP+G+QzerJYF2VxYX+hc6qfs3lWA05a4n+43l8wyEZ7X+Ab++V4PKEdPtuHdJQrsaFLDX3aIWwYeIBlyXuFRE84oG5CfqMTlzSlZjKBFDmVsbsWYKnoJoeCOzP3GZI6/QcQx2UdNprqXrCSHR3pOXk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729506501; c=relaxed/simple; bh=0wktlfJ0cNJMiJpnuxkezOAQtoVwUqlNFNGp6VR88U0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mC5NTqY797CqJd7kKtQHz+TdMFubnECkjQQxS19ZXDVL8Zmw6R5lV9Jq0S5Yex0A9+MGwzZt/QeofvLFMCB31gBCnbCRqLw6yzw8ZpUTnbZoXOQcykpqQVmKSFUki3APZD2MTOEZFJZ4QBm+zdOR+cTDLB//08Phh6DNtrVtEwE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CSav55p1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CSav55p1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 86589C4CEC3; Mon, 21 Oct 2024 10:28:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1729506501; bh=0wktlfJ0cNJMiJpnuxkezOAQtoVwUqlNFNGp6VR88U0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CSav55p1ofjYU3gZa0V763DzMA4p2BxHpKiwgK7MpAmkL52bVi+O78GpfBVLoOrOI mq9JPEjdQ8bNq8KMeiO6gE1qohxhDQaES/Q4K8IQwUMgNAyUNwH0Jjt8rxI5k8WyaZ X2z6MguDv/n0tkQm3WlrgOJaWUrZCaR6DlQ/3LS0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Edward Liaw , Lokesh Gidra , Peter Xu , Shuah Khan , Andrew Morton Subject: [PATCH 6.11 025/135] selftests/mm: replace atomic_bool with pthread_barrier_t Date: Mon, 21 Oct 2024 12:23:01 +0200 Message-ID: <20241021102300.321253158@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241021102259.324175287@linuxfoundation.org> References: <20241021102259.324175287@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Edward Liaw commit e61ef21e27e8deed8c474e9f47f4aa7bc37e138c upstream. Patch series "selftests/mm: fix deadlock after pthread_create". On Android arm, pthread_create followed by a fork caused a deadlock in the case where the fork required work to be completed by the created thread. Update the synchronization primitive to use pthread_barrier instead of atomic_bool. Apply the same fix to the wp-fork-with-event test. This patch (of 2): Swap synchronization primitive with pthread_barrier, so that stdatomic.h does not need to be included. The synchronization is needed on Android ARM64; we see a deadlock with pthread_create when the parent thread races forward before the child has a chance to start doing work. Link: https://lkml.kernel.org/r/20241003211716.371786-1-edliaw@google.com Link: https://lkml.kernel.org/r/20241003211716.371786-2-edliaw@google.com Fixes: cff294582798 ("selftests/mm: extend and rename uffd pagemap test") Signed-off-by: Edward Liaw Cc: Lokesh Gidra Cc: Peter Xu Cc: Shuah Khan Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- tools/testing/selftests/mm/uffd-common.c | 5 +++-- tools/testing/selftests/mm/uffd-common.h | 3 +-- tools/testing/selftests/mm/uffd-unit-tests.c | 14 ++++++++------ 3 files changed, 12 insertions(+), 10 deletions(-) --- a/tools/testing/selftests/mm/uffd-common.c +++ b/tools/testing/selftests/mm/uffd-common.c @@ -18,7 +18,7 @@ bool test_uffdio_wp = true; unsigned long long *count_verify; uffd_test_ops_t *uffd_test_ops; uffd_test_case_ops_t *uffd_test_case_ops; -atomic_bool ready_for_fork; +pthread_barrier_t ready_for_fork; static int uffd_mem_fd_create(off_t mem_size, bool hugetlb) { @@ -519,7 +519,8 @@ void *uffd_poll_thread(void *arg) pollfd[1].fd = pipefd[cpu*2]; pollfd[1].events = POLLIN; - ready_for_fork = true; + /* Ready for parent thread to fork */ + pthread_barrier_wait(&ready_for_fork); for (;;) { ret = poll(pollfd, 2, -1); --- a/tools/testing/selftests/mm/uffd-common.h +++ b/tools/testing/selftests/mm/uffd-common.h @@ -33,7 +33,6 @@ #include #include #include -#include #include "../kselftest.h" #include "vm_util.h" @@ -105,7 +104,7 @@ extern bool map_shared; extern bool test_uffdio_wp; extern unsigned long long *count_verify; extern volatile bool test_uffdio_copy_eexist; -extern atomic_bool ready_for_fork; +extern pthread_barrier_t ready_for_fork; extern uffd_test_ops_t anon_uffd_test_ops; extern uffd_test_ops_t shmem_uffd_test_ops; --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -774,7 +774,7 @@ static void uffd_sigbus_test_common(bool char c; struct uffd_args args = { 0 }; - ready_for_fork = false; + pthread_barrier_init(&ready_for_fork, NULL, 2); fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK); @@ -791,8 +791,9 @@ static void uffd_sigbus_test_common(bool if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args)) err("uffd_poll_thread create"); - while (!ready_for_fork) - ; /* Wait for the poll_thread to start executing before forking */ + /* Wait for child thread to start before forking */ + pthread_barrier_wait(&ready_for_fork); + pthread_barrier_destroy(&ready_for_fork); pid = fork(); if (pid < 0) @@ -833,7 +834,7 @@ static void uffd_events_test_common(bool char c; struct uffd_args args = { 0 }; - ready_for_fork = false; + pthread_barrier_init(&ready_for_fork, NULL, 2); fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK); if (uffd_register(uffd, area_dst, nr_pages * page_size, @@ -844,8 +845,9 @@ static void uffd_events_test_common(bool if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args)) err("uffd_poll_thread create"); - while (!ready_for_fork) - ; /* Wait for the poll_thread to start executing before forking */ + /* Wait for child thread to start before forking */ + pthread_barrier_wait(&ready_for_fork); + pthread_barrier_destroy(&ready_for_fork); pid = fork(); if (pid < 0)