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Thu, 12 Nov 2026 04:11:53 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Thu, 12 Nov 2026 13:11:51 +0100 To: Hao Ge Cc: Uladzislau Rezki , Dev Jain , Suren Baghdasaryan , Andrew Morton , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , Shrikanth Hegde , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Dennis Zhou , Tejun Heo , Christoph Lameter , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, Sashiko Subject: Re: [PATCH v4 4/9] mm/vmalloc: BUG_ON() on an unaligned range in vmap_pages_range_noflush_walk() Message-ID: References: <20261110112546.261415-1-hao.ge@linux.dev> <20261110112546.261415-5-hao.ge@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261110112546.261415-5-hao.ge@linux.dev> X-Stat-Signature: 6jri8pm5ym6hftwjzd8s5c7xm4j4r37u X-Rspamd-Server: rspam01 X-Rspam-User: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: CF7584000E X-HE-Tag: 1794485515-813299 X-HE-Meta: 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 xsJXr9fW 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Nov 10, 2026 at 07:25:41PM +0800, Hao Ge wrote: > The pte loop of vmap_pages_pte_range() maps whole pages and stops > only when addr lands exactly on end. An unaligned end lets addr > jump over it and the loop keeps mapping into whatever follows the > range. An unaligned start maps the page below the range with its > first pte. That corruption is impossible to debug afterwards, so > bug out on addr and end at the entry of > vmap_pages_range_noflush_walk(). > > Reported-by: Sashiko > Signed-off-by: Hao Ge > --- > mm/vmalloc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 27f2674a5556..86fbb1d2b27a 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -698,6 +698,8 @@ static int vmap_pages_range_noflush_walk(unsigned long addr, unsigned long end, > pgtbl_mod_mask mask = 0; > > BUG_ON(addr >= end); > + BUG_ON(!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(end)); > + > But why do we add this? We used to live without it and as far i see we have not gotten any report about any unaligned addresses un-maping. The vmap allocator grantees that va->va_start/end have to be page aligned. -- Uladzislau Rezki