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=ham 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 E9514C2D0F2 for ; Fri, 27 Mar 2020 22:51:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD56C20838 for ; Fri, 27 Mar 2020 22:51:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="DtamsBkg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727848AbgC0Wv2 (ORCPT ); Fri, 27 Mar 2020 18:51:28 -0400 Received: from mail-pg1-f201.google.com ([209.85.215.201]:34720 "EHLO mail-pg1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727787AbgC0WvZ (ORCPT ); Fri, 27 Mar 2020 18:51:25 -0400 Received: by mail-pg1-f201.google.com with SMTP id 12so9175255pgv.1 for ; Fri, 27 Mar 2020 15:51:22 -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=5xyZLq6kEBxznhgqIwr0OhxZhHlqJjOXii0nwjMRAug=; b=DtamsBkgzkP7B1XBVLdKndq6+3upxZDAmgGKmti+fqXF+VX6Bu+IrZnVN97mheuQqg 0K5q84r6w3VZ8YMHETx15fcjD+zhEdyOul3AaBuatOhx4eHWhUMZeBr8vzY38L/H1/B2 n7Q9bf6gcGJFgJeFMnO421VIcqSOfuKKUu4WuumN1lVsbumfYYIr775nAlhBgLKzVceb xwA1lcqG/f9Oj5UMeOxa59jS4DiZ/OUJOlU943HJOxg3B30kR4uOy3SBgLHsLPtRRcZ6 Cr85CorHtVhTXxOq47DJaR2BDuwUIMt8fKb7GpKpz1KZsavqmlgWo6EIi5RuOAyztOJI Vx1g== 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=5xyZLq6kEBxznhgqIwr0OhxZhHlqJjOXii0nwjMRAug=; b=PYha6oRtajDr3FO+NkXyhbPu72MUm5FOLBuTqcHFpza228REbGHKxYqz2PwpxHGUMz H5XEW0bV6jE82vnmwnlR4//guG0PyJzkEV4joGJkmzDoOhdmAFYiYfI0xptwzjNk2mzo ATBUKG1OqecO6JGywQF5yBdxhQWj5Qc6THThx0v+Xmp8nrmAYo7AIg+yZtDvI3UnoXmQ 7QtUi4nEoyvnWuImxyf/moPzqEX9PU1rMzFMiB/kuUMndQz1327q+ERu35zx8g1piliZ x8NQ0/eXPf30WNI54GFCTXMucNmhyJtfQLXfBalA9G7a10sTZ31LsUWtfD7iEqBcAWGt dIOw== X-Gm-Message-State: ANhLgQ2Tb5maBSYew0yH7qT/Zyfh25An0uEW14JOSi4rL384V77o1Qhi oALNTY8IlR3kFeRKXzfq6EuvC+bUWp4= X-Google-Smtp-Source: ADFU+vvTlAXhjp0EkSEWUvLEfpeO7L9FHvOCSALv4WBxIJwVLD9O2V2Nbds1LDlVgla0NKApequRttEkV2M= X-Received: by 2002:a63:2166:: with SMTP id s38mr1524435pgm.83.1585349482143; Fri, 27 Mar 2020 15:51:22 -0700 (PDT) Date: Fri, 27 Mar 2020 15:50:59 -0700 In-Reply-To: <20200327225102.25061-1-walken@google.com> Message-Id: <20200327225102.25061-8-walken@google.com> Mime-Version: 1.0 References: <20200327225102.25061-1-walken@google.com> X-Mailer: git-send-email 2.26.0.rc2.310.g2932bb562d-goog Subject: [PATCH v3 07/10] 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 , Jason Gunthorpe , Markus Elfring , 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 36fb758401d6..a80cf9695514 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -62,4 +62,14 @@ 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); +} + #endif /* _LINUX_MMAP_LOCK_H */ 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_); } } -- 2.26.0.rc2.310.g2932bb562d-goog