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=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 631EDC2D0F0 for ; Wed, 1 Apr 2020 13:46:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2A29A206F5 for ; Wed, 1 Apr 2020 13:46:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="y6eQIehs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732741AbgDANqx (ORCPT ); Wed, 1 Apr 2020 09:46:53 -0400 Received: from merlin.infradead.org ([205.233.59.134]:57622 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732205AbgDANqw (ORCPT ); Wed, 1 Apr 2020 09:46:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=bTIg9/frqj0tTmLnxet1vx3Kwof9z52T8v82iLta588=; b=y6eQIehsd2lZKBw1GndVjHgXhl vWkm5POiPtUDt57kOlC7uLCeVBM6X1K7RdasXLf2u8Njydm09956qElYR5pDt15OJtr+bZs5y74tO XApkXUNA98fOOyXuKaDa+sAZ+kZYdKTafno0qXG2AHWhEETysieDAZpfYo2PigDDCcV6d3ZPAZlkK fcsDaG/9FI8an+McCvzI/hfHmtPr1IGBN6kpiFwgfQygtv/uS69LKENzXhyGEC5RSGDNFcpFqqT4C 7KRhSsAHCG6qFH5yQ+IeC0ObsAwoSf0HWQQ9HFcGskVEqKjd8z7EdqBgynfsz1Gk2BvGtTB5e9aGi LTgdf+cQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jJdhU-0005xz-CH; Wed, 01 Apr 2020 13:46:36 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 1AF6930610E; Wed, 1 Apr 2020 15:46:34 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0456F29D86172; Wed, 1 Apr 2020 15:46:33 +0200 (CEST) Date: Wed, 1 Apr 2020 15:46:33 +0200 From: Peter Zijlstra To: Michel Lespinasse Cc: Andrew Morton , linux-mm , LKML , Laurent Dufour , Vlastimil Babka , Matthew Wilcox , Liam Howlett , Jerome Glisse , Davidlohr Bueso , David Rientjes , Hugh Dickins , Ying Han , Jason Gunthorpe , Markus Elfring Subject: Re: [PATCH v3 07/10] mmap locking API: add mmap_read_release() and mmap_read_unlock_non_owner() Message-ID: <20200401134633.GS20696@hirez.programming.kicks-ass.net> References: <20200327225102.25061-1-walken@google.com> <20200327225102.25061-8-walken@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200327225102.25061-8-walken@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 27, 2020 at 03:50:59PM -0700, Michel Lespinasse wrote: > 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. That code is an absolute abomination and should never have gotten merged. That said; I would prefer a mmap_read_trylock_nonowner() over mmap_read_release() existing. > 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 */