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 7B4AA1E1C11; Mon, 21 Oct 2024 10:28:24 +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=1729506504; cv=none; b=RtR8+uBy0j8SWiUmGxTf+gjF+Fn5sVcl3ZWXpfDoH9FxRvAj58Gr5vj9opgTkUE2E0nffwuPWbXjl7+RVpOmA/IvZf6tTeSdqqyRfvxFNBETjkO8GRcv8AgvHFg6Ez7UNBm7L2oXfIuJxjx5Nffm64e2l3NMVqXtBnyRvIX3v/s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729506504; c=relaxed/simple; bh=5FHWwjaAhNRl7QznjSGKzqygG3BQ+orx/k+HwOCTFU4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=p6+oCkaoffKczjJjQdr5DXDO7MaCBmNAPRms/AeFX1TPOt6TY47gdjdjuvgk82lTuuOuI2SyMPMJqq8orwhanyh8chNFRWDQwwjmXYo4sqc8dBSObXEdWjwRgo4GQx8i4vpkWP07dN8lCb7vwOFykWiuKLJP8Yp7kAzgEpKgki4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YvG0D2f/; 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="YvG0D2f/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE83DC4CEC3; Mon, 21 Oct 2024 10:28:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1729506504; bh=5FHWwjaAhNRl7QznjSGKzqygG3BQ+orx/k+HwOCTFU4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YvG0D2f/V/Pe0djFf01Muf+caATC8fcZ4ovJzlQXS3ELicx4b8bwUWfP3ckAebViD kb2mQH/hXQVXaSDe63lIswoqjMMxU0oOPl1xKz5pEGpjTac/WpLWllf9qvBqfbv8nr u8cg3gnc6a+mS7CReJsv8c3J/hV2Jiz3LxaA9NK0= 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 6.11 026/135] selftests/mm: fix deadlock for fork after pthread_create on ARM Date: Mon, 21 Oct 2024 12:23:02 +0200 Message-ID: <20241021102300.359222525@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: stable@vger.kernel.org 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 e142cc87ac4ec618f2ccf5f68aedcd6e28a59d9d upstream. On Android with arm, there is some synchronization needed to avoid a deadlock when forking after pthread_create. Link: https://lkml.kernel.org/r/20241003211716.371786-3-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-unit-tests.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -241,6 +241,9 @@ static void *fork_event_consumer(void *d fork_event_args *args = data; struct uffd_msg msg = { 0 }; + /* Ready for parent thread to fork */ + pthread_barrier_wait(&ready_for_fork); + /* Read until a full msg received */ while (uffd_read_msg(args->parent_uffd, &msg)); @@ -308,8 +311,12 @@ static int pagemap_test_fork(int uffd, b /* Prepare a thread to resolve EVENT_FORK */ if (with_event) { + pthread_barrier_init(&ready_for_fork, NULL, 2); if (pthread_create(&thread, NULL, fork_event_consumer, &args)) err("pthread_create()"); + /* Wait for child thread to start before forking */ + pthread_barrier_wait(&ready_for_fork); + pthread_barrier_destroy(&ready_for_fork); } child = fork();