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[2a02:3100:a81d:e001:9c9b:db33:f166:fda]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4aa7c5063e3sm212352935e9.0.2026.10.31.10.29.37 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sat, 31 Oct 2026 10:29:38 -0700 (PDT) From: Karl Mehltretter To: Nickolai Zeldovich Cc: Karl Mehltretter , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Andrew Waterman , linux-riscv@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1] riscv: mm: Skip the icache flush for special PTEs Date: Sat, 31 Oct 2026 18:29:30 +0100 Message-Id: <20261031172930.835-1-kmehltretter@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20261017013634.792220-1-nickolai@csail.mit.edu> References: <20261017013634.792220-1-nickolai@csail.mit.edu> 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 Content-Transfer-Encoding: 8bit On Fri, Oct 16, 2026 at 09:36:34PM -0400, Nickolai Zeldovich wrote: > Mapping device memory executable crashes the kernel: an mmap() with > PROT_EXEC of a physical range outside RAM, from /dev/mem, from a PCI > BAR's sysfs resource file, from a frame buffer or from any driver whose > mmap() uses remap_pfn_range(), io_remap_pfn_range() or vmf_insert_pfn(), > oopses in flush_icache_pte() with the page table lock held I hit the same oops on QEMU virt with an executable /dev/mem mapping of 0x200000, which is unassigned there. The kernel was abf8c33470f7 with riscv64 defconfig and OpenSBI v1.8.1. The mmap() oopses in flush_icache_pte() called from do_remap_pfn_range(), and init dies. With this patch the mapping succeeds. Loads, stores and instruction fetches through it raise access faults, which reach user space as SIGSEGV. Tested-by: Karl Mehltretter Thanks, Karl