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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763986618; bh=dZiPM1LFz4RF63yPFs4ZgFUL2y/p+IJlKxTQbSlwnNw=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=Vk41JS3BrTpprUfDmHaAWqzmYN5LKPTP0ikZeODbHurhakhmNlbEtrkZ0/4NlNYP0 UtTmKaGui+1CuOO9Fc+Am73Tx5ttc9GQMIb6wyR1JPjbWt37ealpc6i2ZwvIaw4ks+ IskBvVXpaM256dD32hbqKvx8NITZs2PAXJMTR7mb5vkI/uqgKG/U1gxBrgPxdnUfWY oO7mpKVWZM7yQDfy+uPkrlkPgixJZnkayC7VHnZFnbGELU65n5c3RLwD30onJxBViW QTYAiULrfLWlPgAr1bGaBxZnLYMQtMQKrcVr3dpsU20tbKxrP0F7uz73WMMygGZ2so /lgH1gnK1nKrw== 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 v3] KHO: Fix boot failure due to kmemleak access to non-PRESENT pages In-Reply-To: <20251124025943.94469-1-ranxiaokai627@163.com> (ranxiaokai's message of "Mon, 24 Nov 2025 02:59:43 +0000") References: <20251124025943.94469-1-ranxiaokai627@163.com> Date: Mon, 24 Nov 2025 13:16:55 +0100 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: E21FF40014 X-Stat-Signature: izb5eoom73myujnsq4agpp7p1d6um9qm X-Rspam-User: X-HE-Tag: 1763986619-658648 X-HE-Meta: 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 pM9tohUq k7Ns+8YT6rEienWczHBPSNDjdVrx2ymuw+HaWLpHikirM9JdHbG+5MHT1TQz+A4arwI0SJuNPPR0YTaM75JFfPod9BwUguMKf7i5xNu37CoLHe1bWsJK9TjFJShyHulHXRtmgK05n7QZVHSmha5KCFQZMTlxLAhw/5YNW0a9Vc0e+G9GPojvbxAnv/DtRIWR7CklpQ1sXehnyjiaP+MJrpn75KsD4yfUc0zlNa7HShjkaTbMrBG0BKp5FZ2EE+3KzC6hHaMeUFy+MDcTAJNWxcghC7w== 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 Mon, Nov 24 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) > --- > kernel/liveupdate/kexec_handover.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c > index 224bdf5becb6..c729d455ee7b 100644 > --- a/kernel/liveupdate/kexec_handover.c > +++ b/kernel/liveupdate/kexec_handover.c > @@ -11,6 +11,7 @@ > > #include > #include > +#include > #include > #include > #include > @@ -1369,6 +1370,7 @@ static __init int kho_init(void) > unsigned long count = kho_scratch[i].size >> PAGE_SHIFT; > unsigned long pfn; > > + kmemleak_ignore_phys(kho_scratch[i].addr); Can you please put the explanation you gave in [0] for why this is not necessary in KHO boot as a comment here? After that, Reviewed-by: Pratyush Yadav [0] https://lore.kernel.org/all/20251122175735.92578-1-ranxiaokai627@163.com/ > for (pfn = base_pfn; pfn < base_pfn + count; > pfn += pageblock_nr_pages) > init_cma_reserved_pageblock(pfn_to_page(pfn)); -- Regards, Pratyush Yadav