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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 8C9DAC433E0 for ; Mon, 18 May 2020 10:32:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3C24B207ED for ; Mon, 18 May 2020 10:32:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3C24B207ED Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BF70A900003; Mon, 18 May 2020 06:32:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BA684900002; Mon, 18 May 2020 06:32:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ABBA6900003; Mon, 18 May 2020 06:32:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0094.hostedemail.com [216.40.44.94]) by kanga.kvack.org (Postfix) with ESMTP id 91D64900002 for ; Mon, 18 May 2020 06:32:07 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 555CB33CD for ; Mon, 18 May 2020 10:32:07 +0000 (UTC) X-FDA: 76829474694.23.meat61_86e5783ef275c X-HE-Tag: meat61_86e5783ef275c X-Filterd-Recvd-Size: 4020 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Mon, 18 May 2020 10:32:06 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 66A57AA4F; Mon, 18 May 2020 10:32:07 +0000 (UTC) Subject: Re: [PATCH v5 06/10] mmap locking API: convert nested write lock sites To: Michel Lespinasse , Andrew Morton , linux-mm Cc: LKML , Peter Zijlstra , Laurent Dufour , Matthew Wilcox , Liam Howlett , Jerome Glisse , Davidlohr Bueso , David Rientjes , Hugh Dickins , Ying Han , Jason Gunthorpe , Daniel Jordan References: <20200422001422.232330-1-walken@google.com> <20200422001422.232330-7-walken@google.com> From: Vlastimil Babka Message-ID: <6a23fcce-181b-01ad-4a83-ea24d07ac724@suse.cz> Date: Mon, 18 May 2020 12:32:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200422001422.232330-7-walken@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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: On 4/22/20 2:14 AM, Michel Lespinasse wrote: > Add API for nested write locks and convert the few call sites doing that. > > Signed-off-by: Michel Lespinasse > Reviewed-by: Daniel Jordan Reviewed-by: Vlastimil Babka Perhaps we could even move SINGLE_DEPTH_NESTING into the wrapper? It's unlikely there will be a new user with a different subclass? > --- > arch/um/include/asm/mmu_context.h | 3 ++- > include/linux/mmap_lock.h | 5 +++++ > kernel/fork.c | 2 +- > 3 files changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h > index 62262c5c7785..17ddd4edf875 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 > > @@ -47,7 +48,7 @@ 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, SINGLE_DEPTH_NESTING); > uml_setup_stubs(new); > mmap_write_unlock(new); > } > diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h > index 97ac53b66052..a757cb30ae77 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); > diff --git a/kernel/fork.c b/kernel/fork.c > index 41d3f45c058e..a5d1d20ccba7 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -499,7 +499,7 @@ 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)); >