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[142.167.216.168]) by smtp.gmail.com with ESMTPSA id x28sm9926373qtk.8.2019.08.27.11.41.57 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 27 Aug 2019 11:41:57 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1i2gPl-0006d2-1c; Tue, 27 Aug 2019 15:41:57 -0300 Date: Tue, 27 Aug 2019 15:41:57 -0300 From: Jason Gunthorpe To: Ralph Campbell Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, =?utf-8?B?SsOpcsO0bWU=?= Glisse , Andrew Morton , Christoph Hellwig Subject: Re: [PATCH 2/2] mm/hmm: hmm_range_fault() infinite loop Message-ID: <20190827184157.GA24929@ziepe.ca> References: <20190823221753.2514-1-rcampbell@nvidia.com> <20190823221753.2514-3-rcampbell@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190823221753.2514-3-rcampbell@nvidia.com> User-Agent: Mutt/1.9.4 (2018-02-28) 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, Aug 23, 2019 at 03:17:53PM -0700, Ralph Campbell wrote: > Signed-off-by: Ralph Campbell > mm/hmm.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/hmm.c b/mm/hmm.c > index 29371485fe94..4882b83aeccb 100644 > +++ b/mm/hmm.c > @@ -292,6 +292,9 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end, > hmm_vma_walk->last = addr; > i = (addr - range->start) >> PAGE_SHIFT; > > + if (write_fault && walk->vma && !(walk->vma->vm_flags & VM_WRITE)) > + return -EPERM; Can walk->vma be NULL here? hmm_vma_do_fault() touches it unconditionally. Jason