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[184.145.104.227]) by smtp.gmail.com with ESMTPSA id v6sm1869037qkg.94.2021.04.29.11.38.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Apr 2021 11:38:36 -0700 (PDT) Date: Thu, 29 Apr 2021 14:38:36 -0400 From: Peter Xu To: "Kirill A. Shutemov" Cc: Linus Torvalds , Matthew Wilcox , Dan Williams , Simon Ser , "Kirill A. Shutemov" , Will Deacon , Linux Kernel Mailing List , David Herrmann , "linux-mm@kvack.org" , Greg Kroah-Hartman , "tytso@mit.edu" Subject: Re: Sealed memfd & no-fault mmap Message-ID: <20210429183836.GF8339@xz-x1> References: <20210429154807.hptls4vnmq2svuea@box> MIME-Version: 1.0 In-Reply-To: <20210429154807.hptls4vnmq2svuea@box> 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-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C853D135 X-Stat-Signature: ppb3uhf4fjbs58kwoc9m945mt7fikig9 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=170.10.133.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619721511-690171 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, Apr 29, 2021 at 06:48:07PM +0300, Kirill A. Shutemov wrote: > > Side note: this will only ever work for non-shared mappings. > > I think it's show-stopper for the use-case, no? IIUC, the mappings is used > for communication between a compositor and a client and has to be shared. Yes I had the same doubt.. Besides, we probably don't want to convert all VM_FAULT_SIGBUS to fallback to anonymous pages, as I see that vmf_error() converts mostly everything besides -ENOMEM to VM_FAULT_SIGBUS. Thanks, -- Peter Xu