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Wed, 28 Oct 2026 03:56:02 -0700 (PDT) Received: from [192.168.1.22] ([83.231.69.9]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a978795f4dsm33227565e9.9.2026.10.28.03.56.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Oct 2026 03:56:01 -0700 (PDT) Message-ID: <599fe237-0a05-4e95-b377-7186cb0d761a@gmail.com> Date: Wed, 28 Oct 2026 11:56:00 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] mm/vmalloc: warn on NULL page in remap_vmalloc_range_partial To: Ye Liu , Andrew Morton , Uladzislau Rezki Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ye Liu References: <20261026-vmalloc_remap-v1-0-b7a907814e90@linux.dev> <20261026-vmalloc_remap-v1-2-b7a907814e90@linux.dev> Content-Language: en-US From: "Jose A. Perez de Azpillaga" In-Reply-To: <20261026-vmalloc_remap-v1-2-b7a907814e90@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/26/26 7:09 AM, Ye Liu wrote: > From: Ye Liu > > remap_vmalloc_range_partial() oopses if vmalloc_to_page() returns > NULL, which never happens today because VM_USERMAP areas keep every > page mapped. Add a WARN_ON(!page) to flag a break before the oops. > > Signed-off-by: Ye Liu > --- > mm/vmalloc.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index a888eca016a8..59ba203a4eff 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -4906,6 +4906,7 @@ int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr, > struct page *page = vmalloc_to_page(kaddr); > int ret; > > + WARN_ON(!page); > ret = vm_insert_page(vma, uaddr, page); doesn't this still hand the NULL page to vm_insert_page() right after, so we warn and then oops anyway? wouldn't something like this be what you want here? if (WARN_ON_ONCE(!page)) return -EINVAL; -- cheers, jose a. p-a