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b=enT7i+QGeF5nMmfGvskWHyOmourYf9rryiYO17BNruJNNuOE3iYx0zIYavhZ3/6o8 0LeogTw+IqzuEAPVdEnA0B0qsUL6U3wSLD6fXyZCATBp73Z8UbUquCNIHwtlu0S8i1 ovyrsz2rMipXJIp3sP1/Ezn9ku7QE6ujpTyCbf5/o1yk/FkgNgEGa2NabB7ypXIMro /5+hOa5C2wFoefcDYmrW1oFyAPJ2HSCWxMyDLVKhy3S4x5G6I9wHGUcOt4y0KlDs5N uN3JYWaveYxh0o+R0dceTbU3iVHXvXP6oMVbvOyn4hVqnB37G8EzogSO5I8YFXZhPH 6KsRQiXRcv52g== From: Pratyush Yadav To: ranxiaokai627@163.com Cc: rppt@kernel.org, akpm@linux-foundation.org, catalin.marinas@arm.com, changyuanl@google.com, graf@amazon.com, pasha.tatashin@soleen.com, pratyush@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ran.xiaokai@zte.com.cn Subject: Re: [PATCH v4] KHO: Fix boot failure due to kmemleak access to non-PRESENT pages In-Reply-To: <20251127122700.103927-1-ranxiaokai627@163.com> (ranxiaokai's message of "Thu, 27 Nov 2025 12:27:00 +0000") References: <20251127122700.103927-1-ranxiaokai627@163.com> Date: Thu, 27 Nov 2025 17:20:14 +0100 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: B90941C0018 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 6q6q6xgxknpab1cjrsnxy5m8yq35a9r4 X-HE-Tag: 1764260418-621799 X-HE-Meta: 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 kVRQhZJ5 8ExizKbDG25L7TIqRmyolrKwCu4D1c7LdZrdxyonYZVP2xCavF4OC7xtA0VZxhXjJep1f8D42elV+JujlcSii0bYZorHTYSqKPzvfxP2HDtdUaEZn29j/AuXSCPl7y+OW8/vk8U/pAwpWwCLW5w4ztolidDcpHJuh8sXfSABH/e7l+e8OhFZZjfIYOaRQRgukQJZ5iW19AlDM47+QzUI/KBCBTCju0z1qhk8bjED7fzGGERYB2YWGrhIPCFN3SNJPom4tfbroTNI2i4omFiwZImWQBQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Nov 27 2025, ranxiaokai627@163.com wrote: > From: Ran Xiaokai > > When booting with debug_pagealloc=on while having: > CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT=y > CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=n > the system fails to boot due to page faults during kmemleak scanning. > > This occurs because: > With debug_pagealloc is enabled, __free_pages() invokes > debug_pagealloc_unmap_pages(), clearing the _PAGE_PRESENT bit for > freed pages in the kernel page table. > KHO scratch areas are allocated from memblock and noted by kmemleak. But > these areas don't remain reserved but released later to the page allocator > using init_cma_reserved_pageblock(). This causes subsequent kmemleak scans > access non-PRESENT pages, leading to fatal page faults. > > Mark scratch areas with kmemleak_ignore_phys() after they are allocated > from memblock to exclude them from kmemleak scanning before they are > released to buddy allocator to fix this. > > Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers") > Signed-off-by: Ran Xiaokai > Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Pratyush Yadav Thanks! [...] -- Regards, Pratyush Yadav