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=-14.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNWANTED_LANGUAGE_BODY,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 92138C2D0F1 for ; Thu, 26 Mar 2020 07:03:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 69736207FC for ; Thu, 26 Mar 2020 07:03:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="iSyMxX4G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727771AbgCZHC6 (ORCPT ); Thu, 26 Mar 2020 03:02:58 -0400 Received: from mail-pj1-f73.google.com ([209.85.216.73]:37442 "EHLO mail-pj1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727674AbgCZHCw (ORCPT ); Thu, 26 Mar 2020 03:02:52 -0400 Received: by mail-pj1-f73.google.com with SMTP id d9so3599686pjs.2 for ; Thu, 26 Mar 2020 00:02:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=VJPkzc3VvkOllWTcp9BbAsJmVeKWEmh90BHxu+W0SPE=; b=iSyMxX4G5a6GT1URzk8XL8ZwrcSSNoOluzhd3Q6kKJf5nH+++hgpZc8+Kero84dUQn hQ2l0ZxQZQQeyshFP2toc54vDnLHysbYXhpyJC6jheTkcmZN8mDjHdw2NBXSwW7h5MYl eFWIEY7MQ25gOL2drqrYmIZ85kMwyNVP1qkftYJT/PJLtvyyIPGk2fiv9cgZYsdW5k7x T3QNUFZ2fQNfdMSR6kk2e4WnX8N5FStPAo4wpBtxbPLztNzKo7y6x3vcJav3eSy/ZWHo 3IoJk0FoGf21AMkevgRfR01w37u+uc0IXuVyUn4sRR+82vxaRh+MJbJdMh2J5B3d30Wg CGIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=VJPkzc3VvkOllWTcp9BbAsJmVeKWEmh90BHxu+W0SPE=; b=a7bkS8Xedt6v9KSKaomYBm2hIOKS0RdGbGk6Thy7KUzKUwLfgc6lbrmEXCjgcjgbPX k+wwjGyrCDHZlZBu83Zml1SZUG6wUbGzjGfzg9JEngHoWcOAXfPsIMFTW73Nyk66XAGb X1DO4u1uk/5DoclveUvfleizbtzH1VaM1Q3yhDFNAKZYS2FYQjXDw6+Od2ibFpescQ7w H780QfdlZ2YR5svd4kDYNEtEBCgOrMvXhPczQXJQfPEPzESrWASr4hBdUmgSFff5Sz87 J3e95yPQxaf3+OlVgnLzORvmPKw7gX67S3wdvsVTcMN1Iq6B+lsm5fofIhYuShtIvlSV 824g== X-Gm-Message-State: ANhLgQ09ppSvYHTAKXn3nderl8YEspTwhDEF0j9+ksURfo43QhcPz9Fk J+6zvQILoIqkCMY7J9raePRfVE+2i40= X-Google-Smtp-Source: ADFU+vtbMKdXd0svrxK+Bu5vbiPAjPuFcHvl94Xefvme7ocADs4AOtgtiFcFkT3BbPA5L326zK5JQ17mhTM= X-Received: by 2002:a17:90a:1b22:: with SMTP id q31mr1558267pjq.109.1585206171449; Thu, 26 Mar 2020 00:02:51 -0700 (PDT) Date: Thu, 26 Mar 2020 00:02:33 -0700 In-Reply-To: <20200326070236.235835-1-walken@google.com> Message-Id: <20200326070236.235835-6-walken@google.com> Mime-Version: 1.0 References: <20200326070236.235835-1-walken@google.com> X-Mailer: git-send-email 2.25.1.696.g5e7596f4ac-goog Subject: [PATCH 5/8] mmap locking API: convert nested write lock sites From: Michel Lespinasse To: Andrew Morton , linux-mm Cc: LKML , Peter Zijlstra , Laurent Dufour , Vlastimil Babka , Matthew Wilcox , Liam Howlett , Jerome Glisse , Davidlohr Bueso , David Rientjes , Hugh Dickins , Ying Han , Michel Lespinasse Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add API for nested write locks and convert the few call sites doing that. Signed-off-by: Michel Lespinasse --- arch/um/include/asm/mmu_context.h | 5 +++-- include/linux/mmap_lock.h | 11 +++++++++++ kernel/fork.c | 4 ++-- 3 files changed, 16 insertions(+), 4 deletions(-) diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h index 62262c5c7785..cc15173f7518 100644 --- a/arch/um/include/asm/mmu_context.h +++ b/arch/um/include/asm/mmu_context.h @@ -8,6 +8,7 @@ #include #include +#include #include @@ -47,9 +48,9 @@ static inline void activate_mm(struct mm_struct *old, struct mm_struct *new) * when the new ->mm is used for the first time. */ __switch_mm(&new->context.id); - down_write_nested(&new->mmap_sem, 1); + mmap_write_lock_nested(new, 1); uml_setup_stubs(new); - mmap_write_unlock(new); + mmap_write_unlock_nested(new); } static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h index cffd25afe92b..40a972a26857 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -11,6 +11,11 @@ static inline void mmap_write_lock(struct mm_struct *mm) down_write(&mm->mmap_sem); } +static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass) +{ + down_write_nested(&mm->mmap_sem, subclass); +} + static inline int mmap_write_lock_killable(struct mm_struct *mm) { return down_write_killable(&mm->mmap_sem); @@ -26,6 +31,12 @@ static inline void mmap_write_unlock(struct mm_struct *mm) up_write(&mm->mmap_sem); } +/* Pairs with mmap_write_lock_nested() */ +static inline void mmap_write_unlock_nested(struct mm_struct *mm) +{ + up_write(&mm->mmap_sem); +} + static inline void mmap_downgrade_write_lock(struct mm_struct *mm) { downgrade_write(&mm->mmap_sem); diff --git a/kernel/fork.c b/kernel/fork.c index c321910d46e8..3460308b2213 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -497,7 +497,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, /* * Not linked in yet - no deadlock potential: */ - down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); + mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING); /* No ordering required: file already has been exposed. */ RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); @@ -612,7 +612,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, /* a new mm has just been created */ retval = arch_dup_mmap(oldmm, mm); out: - mmap_write_unlock(mm); + mmap_write_unlock_nested(mm); flush_tlb_mm(oldmm); mmap_write_unlock(oldmm); dup_userfaultfd_complete(&uf); -- 2.25.1.696.g5e7596f4ac-goog