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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 5E650C1B0D9 for ; Mon, 14 Dec 2020 07:02:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E5A122583 for ; Mon, 14 Dec 2020 07:02:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407186AbgLNHCk (ORCPT ); Mon, 14 Dec 2020 02:02:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727969AbgLNHCA (ORCPT ); Mon, 14 Dec 2020 02:02:00 -0500 Received: from mail-pl1-x644.google.com (mail-pl1-x644.google.com [IPv6:2607:f8b0:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87D53C0613CF; Sun, 13 Dec 2020 23:01:20 -0800 (PST) Received: by mail-pl1-x644.google.com with SMTP id b8so2148411plx.0; Sun, 13 Dec 2020 23:01:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=MGjE6Oe6mVSK72UaRSxHAy5QAmJ4uKC6X/D55j0mgnM=; b=kav7cHCYxYQuP8L6G7ZPNKuglYUtblvdQ39I3dnJiAwNZgRQY2TsSzPWGCMwCWqqbb lyVHXwnCB19HUUWSPM+7iWZQz0OepzKgQfDd3n857+uXQgiU4NKMPcUDlyT/4sYEmFkB VmJnHhuKT1eOz8MrHCUwlh/f6XRrW25VPE1LLBcpRjD/VAD8cu0hPT5GbJj6OTQLJs1Z UaeHk1ogQBpVAao0lwAYzGsUDM6hWOv13AyjisgMVY4DffUUaDL6mf4XQOAUIJ3ymFf1 aaau/HcMhHWntY1Po3WpyQXFnY1E86dlvecwBVDhA/IYMqM2O1t7/p9lciMiUUMBthC5 zpjQ== 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=MGjE6Oe6mVSK72UaRSxHAy5QAmJ4uKC6X/D55j0mgnM=; b=NBneY11mZac9fw2/4b3j1sOqqvm5grEyU5y3gqUX7rUQDMo4BKZqdWWW7+tg80dbGJ O7X9xit1Fka6A+OZlak3YZXQvxfWPXZWMDBGCQh8g9QBgxYRNUUUTnaRcNx7fxn9jlxW n05m3XIiP4AvpiMhzrdEpA2hAt7/lvNbvuwcRNvQxFnQ6PUpjI3RYtzojBb/q6kZ17SK jzdqstC90vfIASDmzO+UdeWdErpGy2FTrTlGiJumQNWaymt/X0ds6QElybYrqS2+6aCP V5nhoYEOAryQCpECCzAoZuDboYAnXSN3YjqorZgwJwoCv32MHMhIV0sAFB1ZsCQk+qxN 0J2w== X-Gm-Message-State: AOAM532/XVw8qcoL2p/5HA+N7PwPhegFjOxRYU/K8Hk8rv/vkJuN6oXw P0rjlVm+r6UaVUA+/VakHr21ypOKM0U= X-Google-Smtp-Source: ABdhPJxJOUrDaqX3qExF0UOrRm/OWxZCHdgQA3sDhREGOfNyDxgCR36pLLdlpYpGj+IZTqgueJG6wg== X-Received: by 2002:a17:902:d38b:b029:db:e003:3ff0 with SMTP id e11-20020a170902d38bb02900dbe0033ff0mr17491568pld.7.1607929278513; Sun, 13 Dec 2020 23:01:18 -0800 (PST) Received: from bobo.ozlabs.ibm.com ([220.240.228.148]) by smtp.gmail.com with ESMTPSA id 84sm19570018pfy.9.2020.12.13.23.01.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 13 Dec 2020 23:01:18 -0800 (PST) From: Nicholas Piggin To: linux-kernel@vger.kernel.org Cc: Nicholas Piggin , linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, Anton Blanchard , Andy Lutomirski Subject: [PATCH v2 1/5] lazy tlb: introduce lazy mm refcount helper functions Date: Mon, 14 Dec 2020 16:53:08 +1000 Message-Id: <20201214065312.270062-2-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20201214065312.270062-1-npiggin@gmail.com> References: <20201214065312.270062-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add explicit _lazy_tlb annotated functions for lazy mm refcounting. This makes things a bit more explicit, and allows explicit refcounting to be removed if it is not used. Signed-off-by: Nicholas Piggin --- arch/arm/mach-rpc/ecard.c | 2 +- arch/powerpc/mm/book3s64/radix_tlb.c | 4 ++-- fs/exec.c | 4 ++-- include/linux/sched/mm.h | 11 +++++++++++ kernel/cpu.c | 2 +- kernel/exit.c | 2 +- kernel/kthread.c | 11 +++++++---- kernel/sched/core.c | 15 ++++++++------- 8 files changed, 33 insertions(+), 18 deletions(-) diff --git a/arch/arm/mach-rpc/ecard.c b/arch/arm/mach-rpc/ecard.c index 827b50f1c73e..1b4a41aad793 100644 --- a/arch/arm/mach-rpc/ecard.c +++ b/arch/arm/mach-rpc/ecard.c @@ -253,7 +253,7 @@ static int ecard_init_mm(void) current->mm = mm; current->active_mm = mm; activate_mm(active_mm, mm); - mmdrop(active_mm); + mmdrop_lazy_tlb(active_mm); ecard_init_pgtables(mm); return 0; } diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c index b487b489d4b6..74708aef333e 100644 --- a/arch/powerpc/mm/book3s64/radix_tlb.c +++ b/arch/powerpc/mm/book3s64/radix_tlb.c @@ -658,10 +658,10 @@ static void do_exit_flush_lazy_tlb(void *arg) if (current->active_mm == mm) { WARN_ON_ONCE(current->mm != NULL); /* Is a kernel thread and is using mm as the lazy tlb */ - mmgrab(&init_mm); + mmgrab_lazy_tlb(&init_mm); current->active_mm = &init_mm; switch_mm_irqs_off(mm, &init_mm, current); - mmdrop(mm); + mmdrop_lazy_tlb(mm); } atomic_dec(&mm->context.active_cpus); diff --git a/fs/exec.c b/fs/exec.c index 547a2390baf5..56fc23dcbe4d 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1028,9 +1028,9 @@ static int exec_mmap(struct mm_struct *mm) setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm); mm_update_next_owner(old_mm); mmput(old_mm); - return 0; + } else { + mmdrop_lazy_tlb(active_mm); } - mmdrop(active_mm); return 0; } diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index d5ece7a9a403..94a117160083 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -49,6 +49,17 @@ static inline void mmdrop(struct mm_struct *mm) __mmdrop(mm); } +/* Helpers for lazy TLB mm refcounting */ +static inline void mmgrab_lazy_tlb(struct mm_struct *mm) +{ + mmgrab(mm); +} + +static inline void mmdrop_lazy_tlb(struct mm_struct *mm) +{ + mmdrop(mm); +} + /** * mmget() - Pin the address space associated with a &struct mm_struct. * @mm: The address space to pin. diff --git a/kernel/cpu.c b/kernel/cpu.c index 2b8d7a5db383..a54cdfa08d71 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -576,7 +576,7 @@ static int finish_cpu(unsigned int cpu) */ if (mm != &init_mm) idle->active_mm = &init_mm; - mmdrop(mm); + mmdrop_lazy_tlb(mm); return 0; } diff --git a/kernel/exit.c b/kernel/exit.c index 1f236ed375f8..3711a74fcf4a 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -474,7 +474,7 @@ static void exit_mm(void) __set_current_state(TASK_RUNNING); mmap_read_lock(mm); } - mmgrab(mm); + mmgrab_lazy_tlb(mm); BUG_ON(mm != current->active_mm); /* more a memory barrier than a real lock */ task_lock(current); diff --git a/kernel/kthread.c b/kernel/kthread.c index 933a625621b8..da189e0d26ed 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -1240,14 +1240,14 @@ void kthread_use_mm(struct mm_struct *mm) WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); WARN_ON_ONCE(tsk->mm); + mmgrab(mm); + task_lock(tsk); /* Hold off tlb flush IPIs while switching mm's */ local_irq_disable(); active_mm = tsk->active_mm; - if (active_mm != mm) { - mmgrab(mm); + if (active_mm != mm) tsk->active_mm = mm; - } tsk->mm = mm; switch_mm_irqs_off(active_mm, mm, tsk); local_irq_enable(); @@ -1257,7 +1257,7 @@ void kthread_use_mm(struct mm_struct *mm) #endif if (active_mm != mm) - mmdrop(active_mm); + mmdrop_lazy_tlb(active_mm); to_kthread(tsk)->oldfs = force_uaccess_begin(); } @@ -1280,10 +1280,13 @@ void kthread_unuse_mm(struct mm_struct *mm) sync_mm_rss(mm); local_irq_disable(); tsk->mm = NULL; + mmgrab_lazy_tlb(mm); /* active_mm is still 'mm' */ enter_lazy_tlb(mm, tsk); local_irq_enable(); task_unlock(tsk); + + mmdrop(mm); } EXPORT_SYMBOL_GPL(kthread_unuse_mm); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e7e453492cff..c2f8ea43d29b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3629,13 +3629,14 @@ static struct rq *finish_task_switch(struct task_struct *prev) * rq->curr, before returning to userspace, so provide them here: * * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly - * provided by mmdrop(), + * provided by mmdrop_lazy_tlb(), * - a sync_core for SYNC_CORE. */ if (mm) { membarrier_mm_sync_core_before_usermode(mm); - mmdrop(mm); + mmdrop_lazy_tlb(mm); } + if (unlikely(prev_state == TASK_DEAD)) { if (prev->sched_class->task_dead) prev->sched_class->task_dead(prev); @@ -3739,9 +3740,9 @@ context_switch(struct rq *rq, struct task_struct *prev, /* * kernel -> kernel lazy + transfer active - * user -> kernel lazy + mmgrab() active + * user -> kernel lazy + mmgrab_lazy_tlb() active * - * kernel -> user switch + mmdrop() active + * kernel -> user switch + mmdrop_lazy_tlb() active * user -> user switch */ if (!next->mm) { // to kernel @@ -3749,7 +3750,7 @@ context_switch(struct rq *rq, struct task_struct *prev, next->active_mm = prev->active_mm; if (prev->mm) // from user - mmgrab(prev->active_mm); + mmgrab_lazy_tlb(prev->active_mm); else prev->active_mm = NULL; } else { // to user @@ -3765,7 +3766,7 @@ context_switch(struct rq *rq, struct task_struct *prev, switch_mm_irqs_off(prev->active_mm, next->mm, next); if (!prev->mm) { // from kernel - /* will mmdrop() in finish_task_switch(). */ + /* will mmdrop_lazy_tlb() in finish_task_switch(). */ rq->prev_mm = prev->active_mm; prev->active_mm = NULL; } @@ -7206,7 +7207,7 @@ void __init sched_init(void) /* * The boot idle thread does lazy MMU switching as well: */ - mmgrab(&init_mm); + mmgrab_lazy_tlb(&init_mm); enter_lazy_tlb(&init_mm, current); /* -- 2.23.0