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=-17.4 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,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 DFE91C2D0E8 for ; Thu, 26 Mar 2020 07:03:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B4CF3207FC for ; Thu, 26 Mar 2020 07:03:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="n+aTmufP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727749AbgCZHC6 (ORCPT ); Thu, 26 Mar 2020 03:02:58 -0400 Received: from mail-pj1-f73.google.com ([209.85.216.73]:39976 "EHLO mail-pj1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727717AbgCZHCz (ORCPT ); Thu, 26 Mar 2020 03:02:55 -0400 Received: by mail-pj1-f73.google.com with SMTP id d10so3599071pjz.5 for ; Thu, 26 Mar 2020 00:02:54 -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=DpjYosebPVpuPQwYrgnmEYhswUaFUaz4jId1cdbBdEg=; b=n+aTmufP6JMctYFU46YmDT0hJMNBwCoGeQ2H4e1Y87B+NthqtKUlorXmg3J9jwPZSs Ypc/TZCr5rq/49yZbePRrlndFCIHAsT0y3visA2ncO3JloeeHZaGM01yv7oqY2ZnAs87 uL1BKaOmjXgdyE3bFI339A3v0yGXMoP218gWE4JgTrwJc41oZfto4Pnj8LAnHyva7OWM jZm9JOA6/9wn6Rzab1gJcMc4UqT3i1tgXmqv6eVUEk8xArcYCSESF3U3JaqArLXTx1po 0YYgzzgL+7zDLiLPiXFd+vBdrYPNNlZiDk/eU8OlSBcdxgiAhT7kUSOIPX9kgZ+F4yNX +9aw== 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=DpjYosebPVpuPQwYrgnmEYhswUaFUaz4jId1cdbBdEg=; b=fMqvvapnk61DCtWswnarGxa/b8ScH+tgWQrJ69Bme38bJt1fsur/Z+NWv9yJJqWuzs HYVLhBHmIFGhbIEcFEdtE3WXJa6/M6RpqcXhWN5Og1FN1UlahCx/HC/VUdxxSlmnvRqN DUDfw6Hu/otpBV/OS9o2nvdrfHj7Aj2/ScIeuhFHBXc1HSy5vsVTEaOZkcvXLHReMcGP GEarxkW8omA1n9NbIGB5XWQW7phxaT6sbSIZ6ikJ2TTgjBrvZzi+/0EQr+REw+bJ5ewc 3KsDwY5qpSM1cQKULlNJCE0oMW/Y+U+1LCJ1wZS9kBAfaVFI+fX5JbB4xM+93ZM/xRIW +ukg== X-Gm-Message-State: ANhLgQ0AREgiMwvCyYwmL7krq7EScLGBpwZcQ3EkrSDapUw2YFPZ+66V A6eS+WqyrgTz8Ga7U/YZ46noZOr9d/I= X-Google-Smtp-Source: ADFU+vsBGhjPN1+jWZAin0MSjTA//3xgFIkfN//a4ht+5wmtVuoYamcyNWXv7PgVPkU7CJSVWKZzA7QUhb0= X-Received: by 2002:a17:90a:4809:: with SMTP id a9mr1536611pjh.73.1585206173836; Thu, 26 Mar 2020 00:02:53 -0700 (PDT) Date: Thu, 26 Mar 2020 00:02:34 -0700 In-Reply-To: <20200326070236.235835-1-walken@google.com> Message-Id: <20200326070236.235835-7-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 6/8] mmap locking API: add mmap_read_release() and mmap_read_unlock_non_owner() 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 a couple APIs to allow splitting mmap_read_unlock() into two calls: - mmap_read_release(), called by the task that had taken the mmap lock; - mmap_read_unlock_non_owner(), called from a work queue. These apis are used by kernel/bpf/stackmap.c only. Signed-off-by: Michel Lespinasse --- include/linux/mmap_lock.h | 10 ++++++++++ kernel/bpf/stackmap.c | 9 ++++----- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h index 40a972a26857..00d6cc02581d 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -62,6 +62,16 @@ static inline void mmap_read_unlock(struct mm_struct *mm) up_read(&mm->mmap_sem); } +static inline void mmap_read_release(struct mm_struct *mm, unsigned long ip) +{ + rwsem_release(&mm->mmap_sem.dep_map, ip); +} + +static inline void mmap_read_unlock_non_owner(struct mm_struct *mm) +{ + up_read_non_owner(&mm->mmap_sem); +} + static inline bool mmap_is_locked(struct mm_struct *mm) { return rwsem_is_locked(&mm->mmap_sem) != 0; diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index f2115f691577..413b512a99eb 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -33,7 +33,7 @@ struct bpf_stack_map { /* irq_work to run up_read() for build_id lookup in nmi context */ struct stack_map_irq_work { struct irq_work irq_work; - struct rw_semaphore *sem; + struct mm_struct *mm; }; static void do_up_read(struct irq_work *entry) @@ -41,8 +41,7 @@ static void do_up_read(struct irq_work *entry) struct stack_map_irq_work *work; work = container_of(entry, struct stack_map_irq_work, irq_work); - up_read_non_owner(work->sem); - work->sem = NULL; + mmap_read_unlock_non_owner(work->mm); } static DEFINE_PER_CPU(struct stack_map_irq_work, up_read_work); @@ -332,14 +331,14 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, if (!work) { mmap_read_unlock(current->mm); } else { - work->sem = ¤t->mm->mmap_sem; + work->mm = current->mm; irq_work_queue(&work->irq_work); /* * The irq_work will release the mmap_sem with * up_read_non_owner(). The rwsem_release() is called * here to release the lock from lockdep's perspective. */ - rwsem_release(¤t->mm->mmap_sem.dep_map, _RET_IP_); + mmap_read_release(current->mm, _RET_IP_); } } -- 2.25.1.696.g5e7596f4ac-goog