From patchwork Fri Jul 10 01:56:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicholas Piggin X-Patchwork-Id: 11655401 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BE734618 for ; Fri, 10 Jul 2020 01:57:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7E07220708 for ; Fri, 10 Jul 2020 01:57:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="VdbXxslE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E07220708 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B16146B000A; Thu, 9 Jul 2020 21:57:35 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id AC7B76B000C; Thu, 9 Jul 2020 21:57:35 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9DE436B000D; Thu, 9 Jul 2020 21:57:35 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0216.hostedemail.com [216.40.44.216]) by kanga.kvack.org (Postfix) with ESMTP id 8913C6B000A for ; Thu, 9 Jul 2020 21:57:35 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 43EE518024521 for ; Fri, 10 Jul 2020 01:57:35 +0000 (UTC) X-FDA: 77020504470.07.bomb30_26009d226eca Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id 153521803F9B4 for ; Fri, 10 Jul 2020 01:57:35 +0000 (UTC) X-Spam-Summary: 1,0,0,e0c1dc49e357ee62,d41d8cd98f00b204,npiggin@gmail.com,,RULES_HIT:2:41:355:379:541:800:960:968:973:988:989:1260:1311:1314:1345:1359:1437:1515:1535:1605:1730:1747:1777:1792:1801:2393:2559:2562:2693:3138:3139:3140:3141:3142:3165:3308:3865:3867:3868:3870:3871:3872:4049:4120:4250:4321:4605:5007:6119:6120:6261:6653:7514:7901:7903:8604:9393:9413:10004:11026:11473:11657:11658:11914:12043:12296:12297:12438:12517:12519:12555:12895:12986:13894:14096:14687:14877:21080:21433:21444:21451:21611:21627:21666:21795:21990:30051:30054,0,RBL:209.85.214.193:@gmail.com:.lbl8.mailshell.net-66.100.201.100 62.50.0.100;04yfiz9gtft6fgq9hofofyeaogyr1op6ej84s1u7rapnqh4sawi5mfet8n46b5g.fj4crk3yzq41wui9xu9i4due98aopn9fwscsemhjn7c9c31984ng75nprrntn36.6-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:23,LUA_SUMMARY:none X-HE-Tag: bomb30_26009d226eca X-Filterd-Recvd-Size: 9738 Received: from mail-pl1-f193.google.com (mail-pl1-f193.google.com [209.85.214.193]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Fri, 10 Jul 2020 01:57:32 +0000 (UTC) Received: by mail-pl1-f193.google.com with SMTP id d10so1601362pll.3 for ; Thu, 09 Jul 2020 18:57:32 -0700 (PDT) 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=r3T2qDIJBRF7db837UpeGXiEJ21sH+EdceuIiNA/ntY=; b=VdbXxslEKwgSTBFhB0flLEIm8JG6qFiJq08UUQI+IEUIR6XakM5E7x329H8nKpzRIS k2l/8T1Y2gnFL4xryZLuuDoAVEDnQ0RiFduaS8KpQ0+vKFIEmXcjy30kyZtHC9ZZFL6U zl3ULuN8r/SqvAV1RGq1Ur1gk/GWMxQM4ciFhZRwcyJlxOdsJ1sMVQK31bykWIc8ENQA 4u0+Q2mOD1Lq2yDEzXzkbnrn0odk6FKAFEBIySAD/3Wz3SJZ3OhFBnVPBfM5BvZ8Lmd0 McV0TehMM0Hld7pUfN7AnRHutVDtv6BLSKPr7sVrsbh5OAZysL1vUPFohrXLXRGbqCNq AMRw== 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=r3T2qDIJBRF7db837UpeGXiEJ21sH+EdceuIiNA/ntY=; b=AEww5HZ7iVhJFKzWOM3I1Yrr4Sfo4eR6Wm/JjtH0Mq7Wdxp9GTRg/F4vdSHQnfqBdN DmCfqQzJkXbeI/R9dxFDBiZgqMq/POBwtiFdgeYXN0737ay3HedsU5ZCHkSFf/T2tqsZ aLvF7irYRnghPSkn1zZKDK35n59QdPRqbsQArBZDEPUdvTvyUmV+q5GhJy7FVwf1mBoE Hk1HDMoMMZbkQuM1tCfJgx44IwvbHw0ZHoSlRtsDuNUW1lReALN+M349/MBZUdgELnuS j5VdTW7ZSXgnqVYJvaOv0DatY67KHA2GAFiITmWIXo53QRFfAV/qU2pDKxzRVijIbyMY TmbA== X-Gm-Message-State: AOAM532TpUhxqOjOCAUTqL9WVce3k7ZjKDglWvYqzAFzcM0pVTwPkZFc MiOUY3uDomkbJXIuVWCM9ZY= X-Google-Smtp-Source: ABdhPJyJnvcOSj8f0eErnh4Nc7C/8jUSd3vab/TG0F2X973u875kSeE0uCqdm6s+HyFNPPn5Ydm8Fw== X-Received: by 2002:a17:902:7b92:: with SMTP id w18mr46750453pll.258.1594346251490; Thu, 09 Jul 2020 18:57:31 -0700 (PDT) Received: from bobo.ozlabs.ibm.com (220-245-19-62.static.tpgi.com.au. [220.245.19.62]) by smtp.gmail.com with ESMTPSA id 7sm3912834pgw.85.2020.07.09.18.57.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jul 2020 18:57:31 -0700 (PDT) From: Nicholas Piggin To: linux-arch@vger.kernel.org Cc: Nicholas Piggin , x86@kernel.org, Mathieu Desnoyers , Arnd Bergmann , Peter Zijlstra , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, Anton Blanchard Subject: [RFC PATCH 5/7] lazy tlb: introduce lazy mm refcount helper functions Date: Fri, 10 Jul 2020 11:56:44 +1000 Message-Id: <20200710015646.2020871-6-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20200710015646.2020871-1-npiggin@gmail.com> References: <20200710015646.2020871-1-npiggin@gmail.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 153521803F9B4 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 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: 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/powerpc/kernel/smp.c | 2 +- arch/powerpc/mm/book3s64/radix_tlb.c | 4 ++-- fs/exec.c | 2 +- include/linux/sched/mm.h | 17 +++++++++++++++++ kernel/cpu.c | 2 +- kernel/exit.c | 2 +- kernel/kthread.c | 11 +++++++---- kernel/sched/core.c | 13 +++++++------ 8 files changed, 37 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 73199470c265..ad95812d2a3f 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -1253,7 +1253,7 @@ void start_secondary(void *unused) unsigned int cpu = smp_processor_id(); struct cpumask *(*sibling_mask)(int) = cpu_sibling_mask; - mmgrab(&init_mm); + mmgrab(&init_mm); /* XXX: where is the mmput for this? */ current->active_mm = &init_mm; smp_store_cpu_info(cpu); diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c index b5cc9b23cf02..52730629b3eb 100644 --- a/arch/powerpc/mm/book3s64/radix_tlb.c +++ b/arch/powerpc/mm/book3s64/radix_tlb.c @@ -652,10 +652,10 @@ static void do_exit_flush_lazy_tlb(void *arg) * Must be a kernel thread because sender is single-threaded. */ BUG_ON(current->mm); - mmgrab(&init_mm); + mmgrab_lazy_tlb(&init_mm); switch_mm(mm, &init_mm, current); current->active_mm = &init_mm; - mmdrop(mm); + mmdrop_lazy_tlb(mm); } _tlbiel_pid(pid, RIC_FLUSH_ALL); } diff --git a/fs/exec.c b/fs/exec.c index e2ab71e88293..3a01b2751ea9 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1119,7 +1119,7 @@ static int exec_mmap(struct mm_struct *mm) mmput(old_mm); } else { exit_lazy_tlb(active_mm, tsk); - mmdrop(active_mm); + mmdrop_lazy_tlb(active_mm); } return 0; } diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index 9b026264b445..110d4ad21de6 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -50,6 +50,23 @@ static inline void mmdrop(struct mm_struct *mm) void mmdrop(struct mm_struct *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); +} + +static inline void mmdrop_lazy_tlb_smp_mb(struct mm_struct *mm) +{ + /* This depends on mmdrop providing a full smp_mb() */ + mmdrop(mm); +} + /* * This has to be called after a get_task_mm()/mmget_not_zero() * followed by taking the mmap_lock for writing before modifying the diff --git a/kernel/cpu.c b/kernel/cpu.c index 134688d79589..ff9fcbc4e76b 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -578,7 +578,7 @@ 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 727150f28103..d535da9fd2f8 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -470,7 +470,7 @@ 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 6f93c649aa97..a7133cc2ddaf 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -1238,12 +1238,12 @@ 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); active_mm = tsk->active_mm; - if (active_mm != mm) { - mmgrab(mm); + if (active_mm != mm) tsk->active_mm = mm; - } tsk->mm = mm; switch_mm(active_mm, mm, tsk); task_unlock(tsk); @@ -1253,7 +1253,7 @@ void kthread_use_mm(struct mm_struct *mm) exit_lazy_tlb(active_mm, tsk); if (active_mm != mm) - mmdrop(active_mm); + mmdrop_lazy_tlb(active_mm); to_kthread(tsk)->oldfs = get_fs(); set_fs(USER_DS); @@ -1276,9 +1276,12 @@ void kthread_unuse_mm(struct mm_struct *mm) task_lock(tsk); sync_mm_rss(mm); tsk->mm = NULL; + mmgrab_lazy_tlb(mm); /* active_mm is still 'mm' */ enter_lazy_tlb(mm, tsk); task_unlock(tsk); + + mmdrop(mm); } EXPORT_SYMBOL_GPL(kthread_unuse_mm); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 31e22c79826c..d19f2f517f6c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3302,10 +3302,11 @@ static struct rq *finish_task_switch(struct task_struct *prev) * schedule between user->kernel->user threads without passing though * switch_mm(). Membarrier requires a full barrier after storing to * rq->curr, before returning to userspace, for - * {PRIVATE,GLOBAL}_EXPEDITED. This is implicitly provided by mmdrop(). + * {PRIVATE,GLOBAL}_EXPEDITED. This is implicitly provided by + * mmdrop_lazy_tlb_smp_mb(). */ if (mm) - mmdrop(mm); + mmdrop_lazy_tlb_smp_mb(mm); if (unlikely(prev_state == TASK_DEAD)) { if (prev->sched_class->task_dead) @@ -3410,9 +3411,9 @@ 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 @@ -3420,7 +3421,7 @@ 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 @@ -3438,7 +3439,7 @@ context_switch(struct rq *rq, struct task_struct *prev, if (!prev->mm) { // from kernel exit_lazy_tlb(prev->active_mm, next); - /* will mmdrop() in finish_task_switch(). */ + /* will mmdrop_lazy_tlb() in finish_task_switch(). */ rq->prev_mm = prev->active_mm; prev->active_mm = NULL; }