From patchwork Fri Oct 18 17:17:22 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Edward Liaw X-Patchwork-Id: 13842069 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 89E2E2022EC for ; Fri, 18 Oct 2024 17:18:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729271889; cv=none; b=af+zmjle991pLohOfwB1UrFkrMmdxI2EwZQIQdESJnESK6XmTMGET4DCovX5BdbSv4rdFD08bq/BLP2iWC+5ULHJdMv0xwTTNKWH5CFbBpSLYM00ieqP+w+1BOWK7OXS9/OSv02jf8Xn6Op1X+gSG6ltZQugnSTIBnmKroLXdc8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729271889; c=relaxed/simple; bh=+ENvV6jp4xly72yGU6pYCi2Z9gHRmWJGCF79OSN5WJo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=YxStjVMU/DWAwi9S0q3I83azavnAgCrYUwX/614+PHiYXHuAaguvPwn8Isq0eii9hNfOghJawxSjJrxdumlvUOcmtH1SNgyMZX73TMrcoJeViLwqDMevIEQ8+bp3yeR52zCbfJ+OYRoj+A/gI5NBm3caUXGfwomVRVlcjblFmF8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edliaw.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=zsRSApFu; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edliaw.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="zsRSApFu" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2e2eba0efc6so2639658a91.3 for ; Fri, 18 Oct 2024 10:18:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1729271887; x=1729876687; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=09rqkYzv1mj2i541CG3quDs2Oto4Z5t/2Gr1EPh2MJY=; b=zsRSApFusJfc8T2bVMP5agusEOMIYoh8NWMZu0SvbTVqmumYWcFcr6pFejLAx6NCwm pn2NX2K93Ig0exdwr+EfNVZNSd6GibN7lG1Y1vq3X+m0/FSROBh6xJKWqwO+7adyV7ng Xpi8rYvJPftmSKRRnJoxCZgZHR3e4OwVkJghCXtaGI2e4r+e8deUUAIljgg7ynY9UFnC 7s7gBLVxF3Qy67Z4yhU7F1YuKRLQrGGULABqvym5NopToyWn/Q7r4jr4vkn2Ig/Sh/vn huSnt1YVivht8R5dC+SyAVF5lZx8MBG8Ky/GgZb1Ix5qLvV/c2BGJQO3xH5CDn2Fmw4e OFgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729271887; x=1729876687; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=09rqkYzv1mj2i541CG3quDs2Oto4Z5t/2Gr1EPh2MJY=; b=qX91+8tzqCBeOgeMYZwmQnr2E/ZnrajQ7JSzYwo4OWwvBSahA21T4jLbdBG/IkwTOm cC5nlNFMhpIocFOu3ta66Zpjq++5Pt18lcQ7TK4HwTtht5a/uzbS5fupEkKPRSz9+jWp F7oMfQSwjVWzQTBe+eav9IIk++RHegT5LW1ujxT5Na3U6u9DQHgH8RFYAuIfBzLzkzI2 5k6yq1G2ZPdBjvxnNwtL/+6o6H78UFCE1SlBI5Zbw3n9MBMC/R2fuLCeU+pZU6fpFRYZ ryB4ASx233atd7s3RKzSMrDvTB5GPAe0ubs6go8/Q23+I6eaZpxBpd81RglHSKr8EeYL PLGw== X-Gm-Message-State: AOJu0Yw51Yo1x83LPjnZ71abUmqkWmXPS1dwVG9iiAr8N38a25YOh7zM 5L5n7jzzPfWNeyZPRCBd8fMvPm6wMwyKhzLBJpfHh0sZMu65Raeuwy0HH40GXzfKcv/NYzgX0oS Jrtr6ZZDwxmdzM0pkiq5+FyEA8SaF6z99j4hyii0ChLCetoFUGEUEwhFmW16D7ycfeONGCrJULZ jGXZZklAR0Zku3nuKM9GGGUQOBISRSC3PJtQSswp04PLSV X-Google-Smtp-Source: AGHT+IFCzoFKtcQsGl5HORvI+qdsZRNBp3NS1MD2ovvhIYOdGqZKLlvaQri87EIXebpvo+p31wOY+8NUM+A= X-Received: from edliaw.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:305d]) (user=edliaw job=sendgmr) by 2002:a17:90a:dc02:b0:2e0:72ab:98e9 with SMTP id 98e67ed59e1d1-2e561511115mr9463a91.0.1729271884764; Fri, 18 Oct 2024 10:18:04 -0700 (PDT) Date: Fri, 18 Oct 2024 17:17:22 +0000 In-Reply-To: <20241018171734.2315053-1-edliaw@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241018171734.2315053-1-edliaw@google.com> X-Mailer: git-send-email 2.47.0.105.g07ac214952-goog Message-ID: <20241018171734.2315053-2-edliaw@google.com> Subject: [PATCH 1/3] Revert "selftests/mm: fix deadlock for fork after pthread_create on ARM" From: Edward Liaw To: linux-kselftest@vger.kernel.org, Andrew Morton , Shuah Khan , Edward Liaw , Peter Xu Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, linux-mm@kvack.org, Ryan Roberts This reverts commit e142cc87ac4ec618f2ccf5f68aedcd6e28a59d9d. fork_event_consumer may be called by other tests that do not initialize the pthread_barrier, so this approach is not correct. The subsequent patch will revert to using atomic_bool instead. Fixes: e142cc87ac4e ("fix deadlock for fork after pthread_create on ARM") CC: Ryan Roberts Signed-off-by: Edward Liaw --- tools/testing/selftests/mm/uffd-unit-tests.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index c8a3b1c7edff..3db2296ac631 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -241,9 +241,6 @@ static void *fork_event_consumer(void *data) 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)); @@ -311,12 +308,8 @@ static int pagemap_test_fork(int uffd, bool with_event, bool test_pin) /* 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(); From patchwork Fri Oct 18 17:17:23 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Edward Liaw X-Patchwork-Id: 13842070 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 88690204096 for ; Fri, 18 Oct 2024 17:18:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729271892; cv=none; b=d2XA7vhN1nW1wWITPysm1+caXWrQw1c01LhU83VW9QLBxF06oH0Y38OszHSRXoZvwUqYZIpyYnmeA0OdMVXQGjWYeA3+ArO3y6l0wJkCBeoJHMIR1vNAQCjfIE/htmdorY1yQxKCVzM6mTmwLS125YNFFGVUfnBqbLoZtHnzgbc= ARC-Message-Signature: i=1; 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Fri, 18 Oct 2024 10:18:08 -0700 (PDT) Date: Fri, 18 Oct 2024 17:17:23 +0000 In-Reply-To: <20241018171734.2315053-1-edliaw@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241018171734.2315053-1-edliaw@google.com> X-Mailer: git-send-email 2.47.0.105.g07ac214952-goog Message-ID: <20241018171734.2315053-3-edliaw@google.com> Subject: [PATCH 2/3] Revert "selftests/mm: replace atomic_bool with pthread_barrier_t" From: Edward Liaw To: linux-kselftest@vger.kernel.org, Andrew Morton , Shuah Khan , Edward Liaw , Peter Xu Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, linux-mm@kvack.org, Ryan Roberts This reverts commit e61ef21e27e8deed8c474e9f47f4aa7bc37e138c. uffd_poll_thread may be called by other tests that do not initialize the pthread_barrier, so this approach is not correct. This will revert to using atomic_bool instead. Fixes: e61ef21e27e8 ("selftests/mm: replace atomic_bool with pthread_barrier_t") CC: Ryan Roberts Signed-off-by: Edward Liaw --- 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, 10 insertions(+), 12 deletions(-) diff --git a/tools/testing/selftests/mm/uffd-common.c b/tools/testing/selftests/mm/uffd-common.c index 852e7281026e..717539eddf98 100644 --- 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; -pthread_barrier_t ready_for_fork; +atomic_bool ready_for_fork; static int uffd_mem_fd_create(off_t mem_size, bool hugetlb) { @@ -519,8 +519,7 @@ void *uffd_poll_thread(void *arg) pollfd[1].fd = pipefd[cpu*2]; pollfd[1].events = POLLIN; - /* Ready for parent thread to fork */ - pthread_barrier_wait(&ready_for_fork); + ready_for_fork = true; for (;;) { ret = poll(pollfd, 2, -1); diff --git a/tools/testing/selftests/mm/uffd-common.h b/tools/testing/selftests/mm/uffd-common.h index 3e6228d8e0dc..a70ae10b5f62 100644 --- a/tools/testing/selftests/mm/uffd-common.h +++ b/tools/testing/selftests/mm/uffd-common.h @@ -33,6 +33,7 @@ #include #include #include +#include #include "../kselftest.h" #include "vm_util.h" @@ -104,7 +105,7 @@ extern bool map_shared; extern bool test_uffdio_wp; extern unsigned long long *count_verify; extern volatile bool test_uffdio_copy_eexist; -extern pthread_barrier_t ready_for_fork; +extern atomic_bool ready_for_fork; extern uffd_test_ops_t anon_uffd_test_ops; extern uffd_test_ops_t shmem_uffd_test_ops; diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index 3db2296ac631..b3d21eed203d 100644 --- 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 wp) char c; struct uffd_args args = { 0 }; - pthread_barrier_init(&ready_for_fork, NULL, 2); + ready_for_fork = false; fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK); @@ -791,9 +791,8 @@ static void uffd_sigbus_test_common(bool wp) if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args)) err("uffd_poll_thread create"); - /* Wait for child thread to start before forking */ - pthread_barrier_wait(&ready_for_fork); - pthread_barrier_destroy(&ready_for_fork); + while (!ready_for_fork) + ; /* Wait for the poll_thread to start executing before forking */ pid = fork(); if (pid < 0) @@ -834,7 +833,7 @@ static void uffd_events_test_common(bool wp) char c; struct uffd_args args = { 0 }; - pthread_barrier_init(&ready_for_fork, NULL, 2); + ready_for_fork = false; fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK); if (uffd_register(uffd, area_dst, nr_pages * page_size, @@ -845,9 +844,8 @@ static void uffd_events_test_common(bool wp) if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args)) err("uffd_poll_thread create"); 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Fri, 18 Oct 2024 10:18:12 -0700 (PDT) Date: Fri, 18 Oct 2024 17:17:24 +0000 In-Reply-To: <20241018171734.2315053-1-edliaw@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241018171734.2315053-1-edliaw@google.com> X-Mailer: git-send-email 2.47.0.105.g07ac214952-goog Message-ID: <20241018171734.2315053-4-edliaw@google.com> Subject: [PATCH 3/3] selftests/mm: fix deadlock for fork after pthread_create with atomic_bool From: Edward Liaw To: linux-kselftest@vger.kernel.org, Andrew Morton , Shuah Khan , Edward Liaw , Peter Xu Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, linux-mm@kvack.org, Ryan Roberts Some additional 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. Fixes: cff294582798 ("selftests/mm: extend and rename uffd pagemap test") CC: Ryan Roberts Signed-off-by: Edward Liaw --- tools/testing/selftests/mm/uffd-unit-tests.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index b3d21eed203d..a2e71b1636e7 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -241,6 +241,8 @@ static void *fork_event_consumer(void *data) fork_event_args *args = data; struct uffd_msg msg = { 0 }; + ready_for_fork = true; + /* Read until a full msg received */ while (uffd_read_msg(args->parent_uffd, &msg)); @@ -308,8 +310,11 @@ static int pagemap_test_fork(int uffd, bool with_event, bool test_pin) /* Prepare a thread to resolve EVENT_FORK */ if (with_event) { + ready_for_fork = false; if (pthread_create(&thread, NULL, fork_event_consumer, &args)) err("pthread_create()"); + while (!ready_for_fork) + ; /* Wait for the poll_thread to start executing before forking */ } child = fork();