From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1CF62EBBAB for ; Thu, 28 Aug 2025 08:43:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756370636; cv=none; b=gqcHOD0l6HPIYL2MqdDturruApFiaKKQ8CrpQzr/TJy3pMwJnFNRrxj5cpoQBy0frbfUpFKB2ir2dI0DCe9bb+UJx9zRg0SvCAAftrdXMQDslpj3xTPzmy3sOzeVtGVBg5FCDBs1OkAm+Wq4jl482VKYMW1UztSOw0ZfvW6Itwo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756370636; c=relaxed/simple; bh=dtF3GY0txqUlnrqvH6O65DtDqS/OwB3kNXWzpcWqR1E=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=MD4RRZvDqRu/Hvyg8OrdIdPFOz1IOxRRDPrRqgwHkHjpf4aTnvGhabEpahvWLUTJdzm4tK7neIUjZw5CDH7i8O6+8bW09sfxspLv2zPHU/PqAGYAldqodyHzNElp9B3w2X+bk59SyL16bH7TsQa7q7r1mVAgpyooak26avXjwsM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=p29dZu8R; arc=none smtp.client-ip=209.85.214.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="p29dZu8R" Received: by mail-pl1-f176.google.com with SMTP id d9443c01a7336-248a61a27acso5575335ad.1 for ; Thu, 28 Aug 2025 01:43:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1756370633; x=1756975433; darn=vger.kernel.org; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=jLT2osl3N94HJBBJWKPAk2avCo16Lo88yw1WJjz/wsM=; b=p29dZu8RbOb7kdgd3ZtBE+clhKPFI9QwXvom3vRpu7v7a1BNfOf04PU5L6eIb+0FBr ZJ7mWZfZ2mcXw1UHzo0Vs9d33gwzevLkpSu0YJr2E2fKiWCrzULRqrXnPXb5kSTJ3ER1 lekjoGVJMRclMo/7IcBNF97sqSiEiVAty0uAbdjvDiroutPRgdOc+q//92w7WV45D9pi e1UtjxHBW+qEvW8peS4A2hkdOiciAuwA9wtJGZwCluOTwVwjbKgf5e+TmJfJSwogxt8I /2BnHGYkw7OpFqwTxwo1VxGML77arPgfw3R+ucnsXcN4AJBKvuEX402Rpp+gQpculFrr AiKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756370633; x=1756975433; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=jLT2osl3N94HJBBJWKPAk2avCo16Lo88yw1WJjz/wsM=; b=tXEcV6dq0flpP3M+BLlKZVHpxuQB53lBCa3op+IiX1vVL3SkyNmIWUhk/W7P8hbH7j 5QRds4AHNMQcXOoK7V5PIFwS/4Jkd+VqSQF8xs49/Kv9Hsoi/kI3IdB+iytWAxf0i6ac 7e+j/l//oNEyG6SxFg3+Fk80yuAV9iyb1wXaIkKaAxelgEdJs2eLDlO8/gj8Fg5KrDHS BWIyWOGVE1zCS/s1DnwedFxFq7WAgCLkFNe2lSbqTLI2bZXY2pOTlcma2XQkc239qLJ8 NlN2GjexKiQezJZlxB2qinauTYFETKV1vKnHVapBqBiTaNonrVi7XTXmO4MgOV9fEyJD ojWw== X-Forwarded-Encrypted: i=1; AJvYcCXoMZPIz6qXmPHJ6Bdg7Ub8f3zagDozlgIx2VJRVV/Y+ysXwcRXIaXCIRro9N5i/sheXNQA5M7KVTk=@vger.kernel.org X-Gm-Message-State: AOJu0YwshjuAtOp1j0IadL/yrI0IsmOhZ9qlo0W6TSYKPNeutbQbIS7o fWn4650gRMeZ1uPOE2l9ifMAi7SACru533DZHEgv3AM71EaO+AwBwMCz0XwOXk16KhtI/8T0wHe KIhca9oWXvLMbkv1hKpJRHFqaYMzRVTdSJALRrBZ5 X-Gm-Gg: ASbGnctiyrJEHHPRvbN/lIidcawJI0BBwwT7f4GAyL93Dvnwd7Pw5P1SnDN36u2eqyT khVdYwRBKW/tHMG2ByCy9s7D15GipPTCfkM4A5ReUXjAdStVOPEqKes9Q2MSBrQtqrurKvUiMYt iZfcFgUOQr68bEgdYJ6GDS1OqGL8+W73gPPll2hq3btHTxKr3RQp9MBDj6I6GWXujfQtmFhb5Oc o4XMah4Z1aZgfkpi0LEWwpQD04= X-Google-Smtp-Source: AGHT+IGJmjz+YHPyNxr90AMhiQNNDQu9deq8PWwNfyq+zFWi/YcgUyPYkmS3VX3aACMgtkUmoKeOvBcyBRDmMb3NDeE= X-Received: by 2002:a17:903:3d06:b0:248:8063:a8b4 with SMTP id d9443c01a7336-2488063abcbmr89508125ad.22.1756370632768; Thu, 28 Aug 2025 01:43:52 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-mmc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20250827220141.262669-1-david@redhat.com> <20250827220141.262669-35-david@redhat.com> In-Reply-To: <20250827220141.262669-35-david@redhat.com> From: Marco Elver Date: Thu, 28 Aug 2025 10:43:16 +0200 X-Gm-Features: Ac12FXwMzUnIHp_v7uH0kV3Hu6ram9vqgPmCMZ3TyuNNAlhDfe6K8rTgx1FpO8k Message-ID: Subject: Re: [PATCH v1 34/36] kfence: drop nth_page() usage To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, Alexander Potapenko , Dmitry Vyukov , Andrew Morton , Brendan Jackman , Christoph Lameter , Dennis Zhou , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, iommu@lists.linux.dev, io-uring@vger.kernel.org, Jason Gunthorpe , Jens Axboe , Johannes Weiner , John Hubbard , kasan-dev@googlegroups.com, kvm@vger.kernel.org, "Liam R. Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Lorenzo Stoakes , Marek Szyprowski , Michal Hocko , Mike Rapoport , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org, Zi Yan Content-Type: text/plain; charset="UTF-8" On Thu, 28 Aug 2025 at 00:11, 'David Hildenbrand' via kasan-dev wrote: > > We want to get rid of nth_page(), and kfence init code is the last user. > > Unfortunately, we might actually walk a PFN range where the pages are > not contiguous, because we might be allocating an area from memblock > that could span memory sections in problematic kernel configs (SPARSEMEM > without SPARSEMEM_VMEMMAP). > > We could check whether the page range is contiguous > using page_range_contiguous() and failing kfence init, or making kfence > incompatible these problemtic kernel configs. > > Let's keep it simple and simply use pfn_to_page() by iterating PFNs. > > Cc: Alexander Potapenko > Cc: Marco Elver > Cc: Dmitry Vyukov > Signed-off-by: David Hildenbrand Reviewed-by: Marco Elver Thanks. > --- > mm/kfence/core.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/mm/kfence/core.c b/mm/kfence/core.c > index 0ed3be100963a..727c20c94ac59 100644 > --- a/mm/kfence/core.c > +++ b/mm/kfence/core.c > @@ -594,15 +594,14 @@ static void rcu_guarded_free(struct rcu_head *h) > */ > static unsigned long kfence_init_pool(void) > { > - unsigned long addr; > - struct page *pages; > + unsigned long addr, start_pfn; > int i; > > if (!arch_kfence_init_pool()) > return (unsigned long)__kfence_pool; > > addr = (unsigned long)__kfence_pool; > - pages = virt_to_page(__kfence_pool); > + start_pfn = PHYS_PFN(virt_to_phys(__kfence_pool)); > > /* > * Set up object pages: they must have PGTY_slab set to avoid freeing > @@ -613,11 +612,12 @@ static unsigned long kfence_init_pool(void) > * enters __slab_free() slow-path. > */ > for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) { > - struct slab *slab = page_slab(nth_page(pages, i)); > + struct slab *slab; > > if (!i || (i % 2)) > continue; > > + slab = page_slab(pfn_to_page(start_pfn + i)); > __folio_set_slab(slab_folio(slab)); > #ifdef CONFIG_MEMCG > slab->obj_exts = (unsigned long)&kfence_metadata_init[i / 2 - 1].obj_exts | > @@ -665,10 +665,12 @@ static unsigned long kfence_init_pool(void) > > reset_slab: > for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) { > - struct slab *slab = page_slab(nth_page(pages, i)); > + struct slab *slab; > > if (!i || (i % 2)) > continue; > + > + slab = page_slab(pfn_to_page(start_pfn + i)); > #ifdef CONFIG_MEMCG > slab->obj_exts = 0; > #endif > -- > 2.50.1 > > -- > You received this message because you are subscribed to the Google Groups "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com. > To view this discussion visit https://groups.google.com/d/msgid/kasan-dev/20250827220141.262669-35-david%40redhat.com.