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[174.93.89.182]) by smtp.gmail.com with ESMTPSA id p16sm6558793qtq.24.2021.02.12.14.14.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Feb 2021 14:14:06 -0800 (PST) Date: Fri, 12 Feb 2021 17:14:04 -0500 From: Peter Xu To: Mike Kravetz Cc: Axel Rasmussen , Alexander Viro , Alexey Dobriyan , Andrea Arcangeli , Andrew Morton , Anshuman Khandual , Catalin Marinas , Chinwen Chang , Huang Ying , Ingo Molnar , Jann Horn , Jerome Glisse , Lokesh Gidra , "Matthew Wilcox (Oracle)" , Michael Ellerman , Michal =?utf-8?Q?Koutn=C3=BD?= , Michel Lespinasse , Mike Rapoport , Nicholas Piggin , Shaohua Li , Shawn Anastasio , Steven Rostedt , Steven Price , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Adam Ruprecht , Cannon Matthews , "Dr . David Alan Gilbert" , David Rientjes , Mina Almasry , Oliver Upton Subject: Re: [PATCH v5 04/10] hugetlb/userfaultfd: Unshare all pmds for hugetlbfs when register wp Message-ID: <20210212221404.GE3171@xz-x1> References: <20210210212200.1097784-1-axelrasmussen@google.com> <20210210212200.1097784-5-axelrasmussen@google.com> <517f3477-cb80-6dc9-bda0-b147dea68f95@oracle.com> <20210212211856.GD3171@xz-x1> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline 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 Fri, Feb 12, 2021 at 01:34:03PM -0800, Mike Kravetz wrote: > I'm good with the new MMU_NOTIFY_HUGETLB_UNSHARE and agree with your reasoning > for adding it. I really did not know enough about usage which caused me to > question. It actually is a good question.. Because after a 2nd thought I cannot think of any mmu notifier usage to explicitly listen to huge pmd unshare event - it could be just a too internal impl detail of hugetlbfs. I think any new flag should justify itself when introduced. Before I could justify it, I think MMU_NOTIFIER_CLEAR is indeed more suitable. Thanks, -- Peter Xu