From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FD79C433E2 for ; Tue, 30 Jun 2020 18:45:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E38DF2068F for ; Tue, 30 Jun 2020 18:45:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="tM+dHm+G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726305AbgF3Spc (ORCPT ); Tue, 30 Jun 2020 14:45:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726274AbgF3Sp1 (ORCPT ); Tue, 30 Jun 2020 14:45:27 -0400 Received: from mail-pj1-x1042.google.com (mail-pj1-x1042.google.com [IPv6:2607:f8b0:4864:20::1042]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB6A4C03E97E for ; Tue, 30 Jun 2020 11:45:26 -0700 (PDT) Received: by mail-pj1-x1042.google.com with SMTP id l6so6758252pjq.1 for ; Tue, 30 Jun 2020 11:45:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=6mvVREkDVIeNCrD7qi8PMtAVT+USyRgLji8dDcK1MZI=; b=tM+dHm+GPgciq6qnWfKbJo4Kq5Tayh8q0IFFz6A7wCZjuzwVo/FSrLEbDCu/fnQyBQ jqsvcSJWViFdBp1grNeoyvO7uDBJqWq551Ws9xRJ4INAtpeDu14PXZD4DTga/5DppuZ/ JGneIRzbaZq5NBpkuP4eRsx52aJsUUWyO3n0AFdbCyM4AFTjnYBY8SpWrfh6R8G7P8s5 zLO6a0RrsmwbyZ7b4KwKEQhXLgFxo9rfv/nod+0In7WVqCKZj5EzcL7UkqwEmFU8/bHH Ct2lJoZQXQvMzl/3hHA4JdyGPr8pudetykENgjEM3wfLX5z9C24aUMVSzFVD70zO47wi 1Rzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=6mvVREkDVIeNCrD7qi8PMtAVT+USyRgLji8dDcK1MZI=; b=C0wv832G6KtR7/pnV4gxfmbHkh/ghATFlc4Olf/S3Gm0EzJWrcXOAk/Wfh2NPJqNWZ N8xtik6XlBG0UzCQPqnHp5a7ORnXYgTfChBMoeUAQwOzSwC1D1owJZtHcDZz2+6FXuTM rAfEWPJPE7i3wjiD5dajE/9uTT0FmIqHOnnG1j31HAAPRWHgIKZsgzZPML+KFkQXuGob Pip4DvTwpDc66DzWDpD6OF+E+DDvoMQ5fHX/PusWDjFyALxDpaBti3M1rW7XewrlPQLG 3Hr4rVXQq+lcZ7szvLpB2jdF5Q7IBxBblRmoGdgORygPfr89RnowQe6EMshmDIHn32az lGkA== X-Gm-Message-State: AOAM531IyaL8YEvHEToU10lZoYFAyMHRaOAMKxIl2pfuq2K2IEhCihdj iVPyVgNrfOnNvRncaNVXySOG0ifONwOfJw== X-Google-Smtp-Source: ABdhPJyq42/4G38YKmmdE3qsIa6PN0u2bg0XuBD4ozWyinzBPeXVqQCsyzLFwjhKG9yVm+5zjUzYnQ== X-Received: by 2002:a17:90a:1ac3:: with SMTP id p61mr24724332pjp.23.1593542726013; Tue, 30 Jun 2020 11:45:26 -0700 (PDT) Received: from localhost.localdomain ([2605:e000:100e:8c61:4113:50ea:3eb3:a39b]) by smtp.gmail.com with ESMTPSA id n7sm2898108pjq.22.2020.06.30.11.45.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jun 2020 11:45:25 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org Cc: oleg@redhat.com, peterz@infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Jens Axboe Subject: [PATCH 1/2] task_work: teach task_work_add() to do signal_wake_up() Date: Tue, 30 Jun 2020 12:45:17 -0600 Message-Id: <20200630184518.696101-2-axboe@kernel.dk> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200630184518.696101-1-axboe@kernel.dk> References: <20200630184518.696101-1-axboe@kernel.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org From: Oleg Nesterov So that the target task will exit the wait_event_interruptible-like loop and call task_work_run() asap. The patch turns "bool notify" into 0,TWA_RESUME,TWA_SIGNAL enum, the new TWA_SIGNAL flag implies signal_wake_up(). However, it needs to avoid the race with recalc_sigpending(), so the patch also adds the new JOBCTL_TASK_WORK bit included in JOBCTL_PENDING_MASK. TODO: once this patch is merged we need to change all current users of task_work_add(notify = true) to use TWA_RESUME. Cc: stable@vger.kernel.org # v5.7 Acked-by: Peter Zijlstra (Intel) Signed-off-by: Oleg Nesterov Signed-off-by: Jens Axboe --- include/linux/sched/jobctl.h | 4 +++- include/linux/task_work.h | 5 ++++- kernel/signal.c | 10 +++++++--- kernel/task_work.c | 16 ++++++++++++++-- 4 files changed, 28 insertions(+), 7 deletions(-) diff --git a/include/linux/sched/jobctl.h b/include/linux/sched/jobctl.h index fa067de9f1a9..d2b4204ba4d3 100644 --- a/include/linux/sched/jobctl.h +++ b/include/linux/sched/jobctl.h @@ -19,6 +19,7 @@ struct task_struct; #define JOBCTL_TRAPPING_BIT 21 /* switching to TRACED */ #define JOBCTL_LISTENING_BIT 22 /* ptracer is listening for events */ #define JOBCTL_TRAP_FREEZE_BIT 23 /* trap for cgroup freezer */ +#define JOBCTL_TASK_WORK_BIT 24 /* set by TWA_SIGNAL */ #define JOBCTL_STOP_DEQUEUED (1UL << JOBCTL_STOP_DEQUEUED_BIT) #define JOBCTL_STOP_PENDING (1UL << JOBCTL_STOP_PENDING_BIT) @@ -28,9 +29,10 @@ struct task_struct; #define JOBCTL_TRAPPING (1UL << JOBCTL_TRAPPING_BIT) #define JOBCTL_LISTENING (1UL << JOBCTL_LISTENING_BIT) #define JOBCTL_TRAP_FREEZE (1UL << JOBCTL_TRAP_FREEZE_BIT) +#define JOBCTL_TASK_WORK (1UL << JOBCTL_TASK_WORK_BIT) #define JOBCTL_TRAP_MASK (JOBCTL_TRAP_STOP | JOBCTL_TRAP_NOTIFY) -#define JOBCTL_PENDING_MASK (JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK) +#define JOBCTL_PENDING_MASK (JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK | JOBCTL_TASK_WORK) extern bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask); extern void task_clear_jobctl_trapping(struct task_struct *task); diff --git a/include/linux/task_work.h b/include/linux/task_work.h index bd9a6a91c097..0fb93aafa478 100644 --- a/include/linux/task_work.h +++ b/include/linux/task_work.h @@ -13,7 +13,10 @@ init_task_work(struct callback_head *twork, task_work_func_t func) twork->func = func; } -int task_work_add(struct task_struct *task, struct callback_head *twork, bool); +#define TWA_RESUME 1 +#define TWA_SIGNAL 2 +int task_work_add(struct task_struct *task, struct callback_head *twork, int); + struct callback_head *task_work_cancel(struct task_struct *, task_work_func_t); void task_work_run(void); diff --git a/kernel/signal.c b/kernel/signal.c index 5ca48cc5da76..ee22ec78fd6d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2529,9 +2529,6 @@ bool get_signal(struct ksignal *ksig) struct signal_struct *signal = current->signal; int signr; - if (unlikely(current->task_works)) - task_work_run(); - if (unlikely(uprobe_deny_signal())) return false; @@ -2544,6 +2541,13 @@ bool get_signal(struct ksignal *ksig) relock: spin_lock_irq(&sighand->siglock); + current->jobctl &= ~JOBCTL_TASK_WORK; + if (unlikely(current->task_works)) { + spin_unlock_irq(&sighand->siglock); + task_work_run(); + goto relock; + } + /* * Every stopped thread goes here after wakeup. Check to see if * we should notify the parent, prepare_signal(SIGCONT) encodes diff --git a/kernel/task_work.c b/kernel/task_work.c index 825f28259a19..5c0848ca1287 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -25,9 +25,10 @@ static struct callback_head work_exited; /* all we need is ->next == NULL */ * 0 if succeeds or -ESRCH. */ int -task_work_add(struct task_struct *task, struct callback_head *work, bool notify) +task_work_add(struct task_struct *task, struct callback_head *work, int notify) { struct callback_head *head; + unsigned long flags; do { head = READ_ONCE(task->task_works); @@ -36,8 +37,19 @@ task_work_add(struct task_struct *task, struct callback_head *work, bool notify) work->next = head; } while (cmpxchg(&task->task_works, head, work) != head); - if (notify) + switch (notify) { + case TWA_RESUME: set_notify_resume(task); + break; + case TWA_SIGNAL: + if (lock_task_sighand(task, &flags)) { + task->jobctl |= JOBCTL_TASK_WORK; + signal_wake_up(task, 0); + unlock_task_sighand(task, &flags); + } + break; + } + return 0; } -- 2.27.0