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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 632CAC4332F for ; Mon, 24 Jan 2022 14:30:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B3ACA6B00B9; Mon, 24 Jan 2022 09:30:13 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AC1EE6B00BD; Mon, 24 Jan 2022 09:30:13 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9B0916B00BE; Mon, 24 Jan 2022 09:30:13 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0130.hostedemail.com [216.40.44.130]) by kanga.kvack.org (Postfix) with ESMTP id 88FD26B00B9 for ; Mon, 24 Jan 2022 09:30:13 -0500 (EST) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 47D6A903DE for ; Mon, 24 Jan 2022 14:30:13 +0000 (UTC) X-FDA: 79065415506.09.D36329E Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf17.hostedemail.com (Postfix) with ESMTP id E94D74000B for ; Mon, 24 Jan 2022 14:30:10 +0000 (UTC) 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=Zm003PT7evhPd4nREot8EhRqp/f0aMO4joR+BuKJ58g=; b=IhySRJdN5vM3S13wy+sdRphe4k t6zJEGTbk72IDSl+2t7MkhPx8bzAP3LqAyNpV24t5GLvyOAkWTo1wnDsdoqAVKmApSgOQljn6gJGT phQetzpYZ3dUCOLVFN5LMLlglvsnlN2sWaZfU6uwE1Pb5oExmCxD1bh3GpOk9Tyy87vCsUe7FukFq OAR98VjbnhE3K1bBXy0TKZ227a51Cqvob2SByv5IdN44DOaYhHgdpmrigDx6nn2PdtHLWbSvZcFjA YxvImjlhZdJ3mq38g+pCK1pl3rGKklhwFWixB002O/QoQkYfZgbsSobjZUOIhcSxrQDJ/g2PyCEog 0XYicAxw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nC0M0-000lKE-Nf; Mon, 24 Jan 2022 14:29:57 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 44C523002A6; Mon, 24 Jan 2022 15:29:56 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1C6212B5281A4; Mon, 24 Jan 2022 15:29:56 +0100 (CET) Date: Mon, 24 Jan 2022 15:29:56 +0100 From: Peter Zijlstra To: mingo@redhat.com, tglx@linutronix.de, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, x86@kernel.org, pjt@google.com, posk@google.com, avagin@google.com, jannh@google.com, tdelisle@uwaterloo.ca, mark.rutland@arm.com, posk@posk.io Subject: Re: [RFC][PATCH v2 5/5] sched: User Mode Concurency Groups Message-ID: References: <20220120155517.066795336@infradead.org> <20220120160822.914418096@infradead.org> <20220121114758.GF20638@worktop.programming.kicks-ass.net> <20220121151845.GB22849@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220121151845.GB22849@worktop.programming.kicks-ass.net> Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=IhySRJdN; dmarc=none; spf=none (imf17.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=peterz@infradead.org X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E94D74000B X-Stat-Signature: 7r4ogjawjmkythr1kcbm8iiqjmzkp66a X-HE-Tag: 1643034610-343491 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jan 21, 2022 at 04:18:46PM +0100, Peter Zijlstra wrote: > Something like this, still yuck though. Also still need to write me a > test for this. > > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1300,12 +1300,14 @@ struct task_struct { > clockid_t umcg_clock; > struct umcg_task __user *umcg_task; > > - /* setup by umcg_pin_enter() */ > + /* setup by umcg_pin_pages() */ > struct page *umcg_page; > > struct task_struct *umcg_server; > struct umcg_task __user *umcg_server_task; > struct page *umcg_server_page; > + > + u64 umcg_timeout; > #endif > > struct tlbflush_unmap_batch tlb_ubc; > --- a/kernel/sched/umcg.c > +++ b/kernel/sched/umcg.c > @@ -232,6 +232,8 @@ static int umcg_update_state(struct task > /* Called from syscall enter path and exceptions that can schedule */ > void umcg_sys_enter(struct pt_regs *regs, long syscall) > { > + current->umcg_timeout = 0; > + > /* avoid recursion vs our own syscalls */ > if (syscall == __NR_umcg_wait || > syscall == __NR_umcg_ctl) > @@ -519,6 +521,7 @@ void umcg_notify_resume(struct pt_regs * > struct umcg_task __user *self = tsk->umcg_task; > bool worker = tsk->flags & PF_UMCG_WORKER; > u32 state; > + int ret; > > /* avoid recursion vs schedule() */ > if (worker) > @@ -554,12 +557,17 @@ void umcg_notify_resume(struct pt_regs * > umcg_unpin_pages(); > } > > - switch (umcg_wait(0)) { > + ret = umcg_wait(tsk->umcg_timeout); Oh how I hate signals... this can get scribbled by a syscall/fault from sigcontext :/ Maybe I can recover the timo argument from the original syscall pt_regs.. let me try. > + switch (ret) { > case 0: > case -EINTR: > /* we will resume the wait after the signal */ > break; > > + case -ETIMEDOUT: > + regs_set_return_value(regs, ret); > + break; > + > default: > UMCG_DIE("wait"); > } > @@ -759,6 +767,7 @@ SYSCALL_DEFINE2(umcg_wait, u32, flags, u > switch (ret) { > case 0: /* all done */ > case -EINTR: /* umcg_notify_resume() will continue the wait */ > + tsk->umcg_timeout = timo; > ret = 0; > break; >