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Fri, 23 Dec 2022 06:10:32 -0800 (PST) Date: Fri, 23 Dec 2022 14:10:32 +0000 From: Lorenzo Stoakes To: Christoph Hellwig Cc: Andy Gross , Bjorn Andersson , Konrad Dybcio , Mathieu Poirier , Andrew Morton , Uladzislau Rezki , linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux.dev Subject: Re: [PATCH 2/2] vmalloc: reject vmap with VM_FLUSH_RESET_PERMS Message-ID: References: <20221223092703.61927-1-hch@lst.de> <20221223092703.61927-3-hch@lst.de> <20221223140312.GA26826@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221223140312.GA26826@lst.de> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 2EAC7A0007 X-Stat-Signature: j1hfzm8mu4qwnrwzdjnx5pg7umzup5sf X-HE-Tag: 1671804634-535990 X-HE-Meta: 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 hi45EJrc xUJpAHHpvRoivBmxIqpQoHhDPx6SqQfvU4dTOa+vEcHAVeIeb2F/WqvgzpKduel/+bEUQgqz1UBV3ACqvAr2E4nY7rskiskPRdX8SNq66VaPAWFaX8ebwnqUWkcA3QKTe+hc+AlrcZLN8mgA= 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, Dec 23, 2022 at 03:03:12PM +0100, Christoph Hellwig wrote: > On Fri, Dec 23, 2022 at 10:24:25AM +0000, Lorenzo Stoakes wrote: > > Might it be worth adding a specific vmap mask that explicitly indicates what > > flags are permissible on vmap()? Then this could become e.g.:- > > > > if (WARN_ON_ONCE(flags & ~VM_VMAP_PERMITTED_MASK)) > > return NULL; > > > > And would be self-documenting as to why we are disallowing flags (i.e. they are > > not part of the permitted vmap mask). > > That's probably a good idea. It might need some time to audit > for use of all the flags, though. Perhaps leave that for a later patch (I could take a look as well), but in the meantime might be worth adding a quick comment here indicating why the flag is prohibited?