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b=SiGtHpkH+22ld52BOAx4ticTi7fKCwsjNbskfeIqfkGPOqjZy1shyKWKd2PEMJkaI ds6Cuu7bkYzhKxC97BFKp+ufrESAyd8aoU+b6DGkt0/zRLVjOZ7y+2Cnj1WOjOLJY0 1m/N2Z3e5tTKDk0Ag4jtpUQxp0/0r0hZ7k7gB4+M= Date: Fri, 2 Oct 2026 14:12:23 -0700 From: Andrew Morton To: Dima Koziuk Cc: glider@google.com, elver@google.com, dvyukov@google.com, urezki@gmail.com, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] mm: kmsan: fix iounmap metadata teardown Message-Id: <20261002141223.1ab39d5cd2d65b02dce8ab85@linux-foundation.org> In-Reply-To: <20261002200508.546-1-dmytrokoziuk68@gmail.com> References: <20261002200508.546-1-dmytrokoziuk68@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 9C020A0006 X-Stat-Signature: uba9puq316ymsqqipagdse3tpsdeoyu6 X-Rspam-User: X-HE-Tag: 1790975545-41244 X-HE-Meta: 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 qyLJasH7 p5AF6Z+axs8dP2DCtA8lfqP+9LVIVmHdMxTLhf5pzkoixENr9CpNGADF2E1rZSz7UuAopLjn886V7YDE4YAs007CBbeYz3ClNoOeOnoc0eyOWudW//xvckpkAOX9IS6+ihMjjAKSddQiN753T69vJ8X+bl0aOaXkF+R/aBVZqBwm+22Mg5BuGHfthiRmtnQ4s4o9NY7Sb+XhfYTNwHQjlBFp4Up32jC+wF+I1VWlKHMrps6OMXrou51FuRLMPHBH1rkkBs/hps2hDrZYiEOSzpHCzug== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 2 Oct 2026 23:05:07 +0300 Dima Koziuk wrote: > kmsan_vmalloc_to_page_or_null() rejects addresses outside the regular > vmalloc and module ranges, including the shadow and origin addresses > passed by its callers. As a result, iounmap does not free the metadata > backing pages. Also, the first iteration of the teardown loop > unmaps the entire metadata range, preventing subsequent iterations from > finding their pages even if the address lookup is fixed. > > Factor the page-table walk out of vmalloc_to_page() into > __vmalloc_to_page(), keeping the address check in the public wrapper. > Use the unchecked helper in kmsan_vmalloc_to_page_or_null() and check > for NULL before converting the returned page to a PFN. Mark > __vmalloc_to_page() as __always_inline to avoid an additional function > call in vmalloc_to_page(). > > Move metadata teardown into kmsan_iounmap_pages(). Free the backing > blocks while their mappings are still available, then unmap each > metadata range once and flush its TLB entries. Thanks, I'll queue these for test and further review. Could people please offer opinions on whether we should backport one/both into -stable kernels?