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Sat, 28 Mar 2026 19:01:37 -0700 (PDT) From: Ritesh Harjani (IBM) To: Sourabh Jain , linuxppc-dev@lists.ozlabs.org Cc: Sourabh Jain , Venkat Rao Bagalkote , Aboorva Devarajan , Aditya Gupta , Daniel Axtens , Hari Bathini , Madhavan Srinivasan , Mahesh Salgaonkar , Michael Ellerman , Shivang Upadhyay Subject: Re: [PATCH 1/2] powerpc/kdump: fix KASAN sanitization flag for core_$(BITS).o In-Reply-To: <20260321053121.614022-1-sourabhjain@linux.ibm.com> Date: Sun, 29 Mar 2026 07:26:55 +0530 Message-ID: References: <20260321053121.614022-1-sourabhjain@linux.ibm.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sourabh Jain writes: > KASAN instrumentation is intended to be disabled for the kexec core > code, but the existing Makefile entry misses the object suffix. As a > result, the flag is not applied correctly to core_$(BITS).o. > > So when KASAN is enabled, kexec_copy_flush and copy_segments in > kexec/core_64.c are instrumented, which can result in accesses to > shadow memory via normal address translation paths. Since these run > with the MMU disabled, such accesses may trigger page faults > (bad_page_fault) that cannot be handled in the kdump path, ultimately > causing a hang and preventing the kdump kernel from booting. The same > is true for kexec as well, since the same functions are used there. > > Update the entry to include the “.o” suffix so that KASAN > instrumentation is properly disabled for this object file. > > Fixes: 2ab2d5794f14 ("powerpc/kasan: Disable address sanitization in kexec paths") > Reported-by: Venkat Rao Bagalkote > Closes: https://lore.kernel.org/all/1dee8891-8bcc-46b4-93f3-fc3a774abd5b@linux.ibm.com/ Nice catch. Indeed seems to be missed in the Fixes patch. I think you might want to Cc: stable too, so that it is auto backported to previous stable kernel releases too. The Fixes patch was added in v5.19 kernel, maybe we weren't testing KASAN + Kdump, but it's worth backporting to all stable kernel releases, IMO. LGTM, please feel free to add: Reviewed-by: Ritesh Harjani (IBM)