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Thu, 12 Nov 2026 04:23:39 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Thu, 12 Nov 2026 13:23:36 +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 Subject: Re: [PATCH v4 3/9] mm/vmalloc: BUG_ON() on an unaligned range in vmap_range_noflush() Message-ID: References: <20261110112546.261415-1-hao.ge@linux.dev> <20261110112546.261415-4-hao.ge@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261110112546.261415-4-hao.ge@linux.dev> X-Stat-Signature: 9r1mrnan9hxhjn5y9918x37oskhm99kq X-Rspamd-Queue-Id: 859B1180002 X-Rspam-User: X-Rspamd-Server: rspam08 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-HE-Tag: 1794486221-728391 X-HE-Meta: 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 NE6Sf/pY WKTd1kAb4AU7xWU6BZ7Fk9w3Yr1zzC9sCmAPvAsLqXNEpaY8a7a7yxeesCFgW9OgUhtoaH4Ntt+CeflWymj2NJB+ZCFRsGU7xV/MHSpQDzYuybM4KKos82WJVWxBEjJtGnZrLNvT+Yziq7aZV2JCgymnyQjBi6hmgmC7jXdVmb9jVASLR2zXQe3euWRBp4uOYJKUg0kEpRJr932ESS5/opIJIjauVXY1MkuAXVtpOuV57PJKFN0Fqe610IWc5UNHMqY+pfr6J1fETtLX4f7wRLuiuGazX80h1PWBCrca+QQyCrEOtWltLCWJn11Sz4WmwZYzImLZjZMfKsllRH4a2NkzCKaxJhMEp/LG1oKWdTpJIovf+ujp2m+yYsvVOK9aO7qKQdGlu39wCqkubj7dS57FdxBIyLO4dOw38hRPh2B4nyuNyvX5qmbVIS+UIef70B+YugYDA4saMlCcrKT4LqCKz1HAmseV93WJPO0PKVRkI+DiJv9SlzLEH4F1W8uapDR9ceXXYGavai79vIZ/E8Kw8l5bNo6Z52i+TrHCftZY2i7YJ7RaeBIYbdEYg6YdKxSH+GSLV+p8LIagGCCrrwK7ecQ== 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 07:25:40PM +0800, Hao Ge wrote: > commit a739e6b557af ("mm: vmalloc: WARN_ON if mapping size is not > PAGE_SIZE aligned") put the check in vmap_pte_range(), which is too > late, because the upper levels may already have installed page > tables for a range that is rejected anyway. > > The pte loop 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 past the range. An unaligned start maps the > page below the range and usually misses end too. Such a range is > never a legitimate request, and the corruption it leaves behind is > hard to attribute to the caller afterwards, so bug out on addr and > end at the entry of vmap_range_noflush() and drop the check from > vmap_pte_range(). > > Signed-off-by: Hao Ge > --- > mm/vmalloc.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 093b8d5f7b0e..27f2674a5556 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -125,9 +125,6 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, > unsigned long size; > unsigned int nr_pages; > > - if (WARN_ON_ONCE(!PAGE_ALIGNED(end - addr))) > - return -EINVAL; > - > pfn = phys_addr >> PAGE_SHIFT; > pte = pte_alloc_kernel_track(pmd, addr, mask); > if (!pte) > @@ -347,6 +344,7 @@ static int vmap_range_noflush(unsigned long addr, unsigned long end, > */ > might_sleep(); > BUG_ON(addr >= end); > + BUG_ON(!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(end)); > > start = addr; > pgd = pgd_offset_k(addr); > -- > 2.25.1 > Like Suren proposed, there is only one user of vmap_range_noflush() it is vmap_page_range() function. You can add warn-on-once() there and bail out. Do not add BUG_ON(). -- Uladzislau Rezki