Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Date:   Tue, 26 Apr 2022 12:34:12 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc:     Ira Weiny <ira.weiny@intel.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Peter Collingbourne <pcc@google.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/highmem: VM_BUG_ON() if offset + len > PAGE_SIZE
Message-Id: <20220426123412.51fb58780a8fe2b32c7814ce@linux-foundation.org>
In-Reply-To: <20220426193020.8710-1-fmdefrancesco@gmail.com>
References: <20220426193020.8710-1-fmdefrancesco@gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Tue, 26 Apr 2022 21:30:20 +0200 "Fabio M. De Francesco" <fmdefrancesco@gmail.com> wrote:

> Add VM_BUG_ON() bounds checking to make sure that, if "offset + len>
> PAGE_SIZE", memset() does not corrupt data in adjacent pages.
> 

hm, why?  To match all the other functions in there?

I suppose that's logical.  Or we could just delete all the other
VM_BUG_ON()s.  Have any of them proven to be at all useful?