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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 6D4B3C48BE8 for ; Tue, 15 Jun 2021 21:51:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4FAA9611AB for ; Tue, 15 Jun 2021 21:51:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231396AbhFOVxU (ORCPT ); Tue, 15 Jun 2021 17:53:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230081AbhFOVxR (ORCPT ); Tue, 15 Jun 2021 17:53:17 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51961C061574; Tue, 15 Jun 2021 14:51:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=N7GqmOX/LrLVjhMA+EGbHb8euLArRMk+/0HSOfKlkms=; b=EYhLqcYbLbuGDX2J4p1lfl4xus 1R6WpuzXS1jERG1BFYXYI6Cshp6bERYc2+/1DMJj7EnEM1aKRkI1NwyGU/MKV5GqW8UgMQiuCX2vH e1vjwiuAeWmGEzFIROLjnTUNFjvQSJ3N/E4s9pxSaOe8+Sfu7i8TX1WR7gqNcWbIznRZ/rLSngjUC E1R2CHViHRzY5y3DvRWMK8WE26Dnx+yDC2kVSWW3geZ+Q8HFKCFykqtI4/ps+yBuXR9BCo93VavXc NSMnG/ridpr9iiIfUJrS9wQ/seTzpN3wYakA+z4MnFn5uGyx88mCHUcyI4WAm7RgRVkbeP5eZb/1n dkYOVQ1A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1ltGwh-007Hsf-5C; Tue, 15 Jun 2021 21:50:11 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 385F3982227; Tue, 15 Jun 2021 23:50:05 +0200 (CEST) Date: Tue, 15 Jun 2021 23:50:05 +0200 From: Peter Zijlstra To: Oleg Nesterov Cc: rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, Will Deacon , Tejun Heo , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH] freezer,sched: Rewrite core freezer logic Message-ID: <20210615215005.GD4272@worktop.programming.kicks-ass.net> References: <20210614154246.GB13677@redhat.com> <20210614161221.GC68749@worktop.programming.kicks-ass.net> <20210614165422.GC13677@redhat.com> <20210614183801.GE68749@worktop.programming.kicks-ass.net> <20210615154539.GA30333@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210615154539.GA30333@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 15, 2021 at 05:45:39PM +0200, Oleg Nesterov wrote: > On 06/14, Peter Zijlstra wrote: > > > > One more thing; if I add additional state bits to preserve > > __TASK_{TRACED,STOPPED}, then I need to figure out at thaw time if we've > > missed a wakeup or not. > > > > Do we have sufficient state for that? If so, don't we then also not have > > sufficient state to tell if a task should've been TRACED/STOPPED in the > > first place? > > Not sure I understand you, probably not, but I think the answer is "no" ;) I was thinking something like the below, such that we can then write something like: void __thaw_special(struct task_struct *p) { spin_lock(&t->sighand->siglock); if (p->ptrace) { unsigned int state = __TASK_TRACED; if (!(p->ptrace & PT_STOPPED)) goto unlock; if (p->ptrace & PT_STOPPED_FATAL) { state |= TASK_WAKEKILL; if (__fatal_signal_pending(p)) goto unlock; } set_special_state(state); } else if ((p->jobctl & JOBCTL_STOP_PENDING) && !__fatal_signal_pending(p)) { set_special_state(TASK_STOPPED); } unlock: spin_unlock(&t->sighand->siglock); } --- diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index b5ebf6c01292..2123d6543125 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -28,30 +28,36 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr, * flags. When the a task is stopped the ptracer owns task->ptrace. */ -#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */ -#define PT_PTRACED 0x00000001 -#define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */ +#define PT_PTRACED 0x00000001 // 0x00000001 +#define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */ // 0x00000002 #define PT_OPT_FLAG_SHIFT 3 /* PT_TRACE_* event enable flags */ #define PT_EVENT_FLAG(event) (1 << (PT_OPT_FLAG_SHIFT + (event))) -#define PT_TRACESYSGOOD PT_EVENT_FLAG(0) -#define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK) -#define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK) -#define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE) -#define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC) -#define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE) -#define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT) -#define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP) - -#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT) -#define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT) + +#define PT_TRACESYSGOOD PT_EVENT_FLAG(0) // 0x00000008 +#define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK) // 0x00000010 +#define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK) // 0x00000020 +#define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE) // 0x00000040 +#define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC) // 0x00000080 +#define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE) // 0x00000100 +#define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT) // 0x00000200 +#define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP) // 0x00000400 + +#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */// 0x00010000 +#define PT_STOPPED 0x00020000 // 0x00020000 +#define PT_STOPPED_FATAL 0x00040000 // 0x00040000 + +#define PT_STOPPED_MASK (PT_STOPPED|PT_STOPPED_FATAL) + +#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT) // 0x00800000 +#define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT) // 0x01000000 /* single stepping state bits (used on ARM and PA-RISC) */ #define PT_SINGLESTEP_BIT 31 -#define PT_SINGLESTEP (1<ptrace &= ~PT_STOPPED_MASK; signal_wake_up_state(t, resume ? __TASK_TRACED : 0); } diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 2997ca600d18..4fc4e1f91ecd 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -197,6 +197,8 @@ static bool ptrace_freeze_traced(struct task_struct *task) spin_lock_irq(&task->sighand->siglock); if (task_is_traced(task) && !looks_like_a_spurious_pid(task) && !__fatal_signal_pending(task)) { + task->ptrace &= ~PT_STOPPED_MASK; + task->ptrace |= PT_STOPPED; task->state = __TASK_TRACED; ret = true; } @@ -218,10 +220,13 @@ static void ptrace_unfreeze_traced(struct task_struct *task) */ spin_lock_irq(&task->sighand->siglock); if (task->state == __TASK_TRACED) { - if (__fatal_signal_pending(task)) + if (__fatal_signal_pending(task)) { + task->ptrace &= ~PT_STOPPED_MASK; wake_up_state(task, __TASK_TRACED); - else + } else { + task->ptrace |= PT_STOPPED_MASK; task->state = TASK_TRACED; + } } spin_unlock_irq(&task->sighand->siglock); } @@ -835,8 +840,6 @@ static long ptrace_get_rseq_configuration(struct task_struct *task, static int ptrace_resume(struct task_struct *child, long request, unsigned long data) { - bool need_siglock; - if (!valid_signal(data)) return -EIO; @@ -877,13 +880,11 @@ static int ptrace_resume(struct task_struct *child, long request, * status and clears the code too; this can't race with the tracee, it * takes siglock after resume. */ - need_siglock = data && !thread_group_empty(current); - if (need_siglock) - spin_lock_irq(&child->sighand->siglock); + spin_lock_irq(&child->sighand->siglock); child->exit_code = data; + child->ptrace &= ~PT_STOPPED_MASK; wake_up_state(child, __TASK_TRACED); - if (need_siglock) - spin_unlock_irq(&child->sighand->siglock); + spin_unlock_irq(&child->sighand->siglock); return 0; } diff --git a/kernel/signal.c b/kernel/signal.c index f7c6ffcbd044..35cdb92b7f1d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2195,6 +2195,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t return; } + current->ptrace |= PT_STOPPED_MASK; set_special_state(TASK_TRACED); /*