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Fri, 23 Dec 2022 02:24:25 -0800 (PST) Date: Fri, 23 Dec 2022 10:24:25 +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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221223092703.61927-3-hch@lst.de> X-Rspamd-Queue-Id: 168E220012 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: beenhnejrt3nxtdhbzsy76ogia6shmsb X-HE-Tag: 1671791067-762649 X-HE-Meta: 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 /RzmQqCK bL9q8i7M9n8PkftZuRh3ujx7xJLkxkCA3X62QgeVfBMyxWJxN/4RY1GkqUSHcRwTzMsdNcuJSxVFpYpgAk9AKEJhZmUDmgtscQGPggDpSeJQgcNd2nNjOrWlNmbGghiSA1ktpNJpWcG84aYM= 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 10:27:03AM +0100, Christoph Hellwig wrote: > VM_FLUSH_RESET_PERMS is just for use with vmalloc as it is tied to freeing > the underlying pages. > > Signed-off-by: Christoph Hellwig > --- > mm/vmalloc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 9e30f0b3920325..88a644cde9fb12 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2849,6 +2849,9 @@ void *vmap(struct page **pages, unsigned int count, > > might_sleep(); > > + if (WARN_ON_ONCE(flags & VM_FLUSH_RESET_PERMS)) > + return NULL; > + 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).