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x-ptr=pass x-ptr-helo=mail.kernel.org x-ptr-lookup=mail.kernel.org; x-return-mx=pass smtp.domain=kernel.org smtp.result=pass smtp_is_org_domain=yes header.domain=kernel.org header.result=pass header_is_org_domain=yes; x-tls=pass version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128; x-vs=clean score=-100 state=0 X-ME-VSCategory: clean X-Remote-Delivered-To: security@kernel.org DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 68B05217D8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=htejun@gmail.com X-Google-Smtp-Source: AG47ELvSHhjy6lo/+/k27olFJmd9MqK1EeDCAqvIETR1DMh5023ujwD4gLOv2Zat7m/+o1lRCTrMdw== Sender: Tejun Heo Date: Wed, 21 Mar 2018 10:53:56 -0700 From: Tejun Heo To: Oleg Nesterov Cc: torvalds@linux-foundation.org, jannh@google.com, paulmck@linux.vnet.ibm.com, bcrl@kvack.org, viro@zeniv.linux.org.uk, kent.overstreet@gmail.com, security@kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 8/8] fs/aio: Use rcu_work instead of explicit rcu and work item Message-ID: <20180321175356.GD2149215@devbig577.frc2.facebook.com> References: <20180314194205.1651587-1-tj@kernel.org> <20180314194515.1661824-1-tj@kernel.org> <20180314194515.1661824-8-tj@kernel.org> <20180321155812.GA9382@redhat.com> <20180321164000.GC2149215@devbig577.frc2.facebook.com> <20180321171743.GA12834@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180321171743.GA12834@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Hello, On Wed, Mar 21, 2018 at 06:17:43PM +0100, Oleg Nesterov wrote: > Mostly I am asking because I do not really understand > "[PATCH 6/8] RCU, workqueue: Implement rcu_work". > > I mean, the code looks simple and correct but why does it play with > WORK_STRUCT_PENDING_BIT? IOW, I do not see a "good" use-case when 2 or more > queue_rcu_work()'s can use the same rwork and hit work_pending() == T. And > what the caller should do if queue_rcu_work() returns false? It's just following standard workqueue conventions. We can try to make it more specialized but then flush_rcu_work()'s behavior would have to different too and it gets confusing quickly. Unless there are overriding reasons to deviate, I'd like to keep it consistent. Thanks. -- tejun