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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id r23si5682130pgk.126.2019.06.15.06.59.09 for (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Sat, 15 Jun 2019 06:59:09 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of batv+78a6abdb7ec5759febfc+5774+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=SghgOUqO; spf=pass (google.com: best guess record for domain of batv+78a6abdb7ec5759febfc+5774+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+78a6abdb7ec5759febfc+5774+infradead.org+hch@bombadil.srs.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=uw+8Gsob+xo/SGAw3aMo5AOaLhno7qEOpvZ++8fuMSg=; b=SghgOUqONoSRbIHgI8mPRhVMT twgH3naz+biFngZQOZd3Gfiqe8dVH42nugcD5e0Tep/6FkDlqVGXX8DlYOQhyRRP6O7klcnieXo6i jjlWR3luZbcxwFtG0w3KW2LSIGImE5ebS3p7jjD9mPgIU2cJ/x+/iiSAFR3Fg82dE+1fzRwqKEH/h Qdaga43CwL64GRoC9uL+zhZeMgz+tE9LTXAFyT71viusNdb66qP93qtAQnYFYqKjCTVSTAa2XiEkP ZZPRbeKA7C1RqLqGOWq8mHy5rS6D0nKeKB/hd12WNrXe6DiUV4EaD/0y/ZC6hyyT0vzri7JJQ6WkG r0yItbY3w==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hc9D0-00057j-88; Sat, 15 Jun 2019 13:59:06 +0000 Date: Sat, 15 Jun 2019 06:59:06 -0700 From: Christoph Hellwig To: Jason Gunthorpe Cc: Jerome Glisse , Ralph Campbell , John Hubbard , Felix.Kuehling@amd.com, linux-rdma@vger.kernel.org, linux-mm@kvack.org, Andrea Arcangeli , dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, Ben Skeggs , Jason Gunthorpe , Ira Weiny , Philip Yang Subject: Re: [PATCH v3 hmm 02/12] mm/hmm: Use hmm_mirror not mm as an argument for hmm_range_register Message-ID: <20190615135906.GB17724@infradead.org> References: <20190614004450.20252-1-jgg@ziepe.ca> <20190614004450.20252-3-jgg@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190614004450.20252-3-jgg@ziepe.ca> User-Agent: Mutt/1.11.4 (2019-03-13) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html 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 Thu, Jun 13, 2019 at 09:44:40PM -0300, Jason Gunthorpe wrote: > From: Jason Gunthorpe > > Ralph observes that hmm_range_register() can only be called by a driver > while a mirror is registered. Make this clear in the API by passing in the > mirror structure as a parameter. > > This also simplifies understanding the lifetime model for struct hmm, as > the hmm pointer must be valid as part of a registered mirror so all we > need in hmm_register_range() is a simple kref_get. Looks good, at least an an intermediate step: Reviewed-by: Christoph Hellwig > index f6956d78e3cb25..22a97ada108b4e 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -914,13 +914,13 @@ static void hmm_pfns_clear(struct hmm_range *range, > * Track updates to the CPU page table see include/linux/hmm.h > */ > int hmm_range_register(struct hmm_range *range, > - struct mm_struct *mm, > + struct hmm_mirror *mirror, > unsigned long start, > unsigned long end, > unsigned page_shift) > { > unsigned long mask = ((1UL << page_shift) - 1UL); > - struct hmm *hmm; > + struct hmm *hmm = mirror->hmm; > > range->valid = false; > range->hmm = NULL; > @@ -934,20 +934,15 @@ int hmm_range_register(struct hmm_range *range, > range->start = start; > range->end = end; But while you're at it: the calling conventions of hmm_range_register are still rather odd, as the staet, end and page_shift arguments are only used to fill out fields in the range structure passed in. Might be worth cleaning up as well if we change the calling convention.