From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 497F61073CA5 for ; Wed, 8 Apr 2026 12:17:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=o7VsHLXptJ95COxSKs0ScfqIswvohnDgBMdUEw4P/Go=; b=M5Vm2766kQPQVScExHi7lVqgLN RZ7WzxByDLGhEBqGuuBPFcl0+CrejydcLR+YxLZAEyUPKltJEf0ajGMvN1fqmmjEoG9ezb1hlh38H KttomWQn/0qLVcuTRv3Eb3O9FsYnPffhpes25HvAbChxYf6YYFJZkFERFII++dtAREdlgdno6V7Ml uT5ZyLDVLFfOitmrRQzRk/+OU5H99547l+OzAk64xzXezg9GZ+9BceKU7RYHOkgXGwzkW35N7fMKN KzEn47hC5RURO5ygAKkzEOtc2OT0tgm7BE2yV5SOLUNP0HNRQepimvRVXVaQqXgFbPQsc9GFCmsLb l+Q9VxSw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wARqc-00000008oYz-3kgJ; Wed, 08 Apr 2026 12:17:30 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wARqa-00000008oYU-0U65 for linux-arm-kernel@lists.infradead.org; Wed, 08 Apr 2026 12:17:29 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 6DCA340A9D; Wed, 8 Apr 2026 12:17:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA007C19421; Wed, 8 Apr 2026 12:17:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775650647; bh=9RDpTJaswPF4RZD8fDr9UWPGxniVyHEL2oMP01MICtA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=hf9bYJ80e8mo7uRTzk9PvAOXk24thjgM3Nx0h4knc6Ejt/QopDc0w/KMYiqTUqdSU NV1Tu4lsemjq1nT95EK5hf9j8btk62yCVgGbOc5EgUh0OYMcpj5nT8S/Eazk4u3qGI 3IHexIj6haCdm0fEUCyTc3grx57THgzuz4aQE6HNINwx/Qp9AB0jZXRC1etuL4kcZu Q+4aijjuRJwTHs0bbQuW69upCf/vnBWzXysURO54rAHDaPSh53SlJyjrjvaKy7oBWY ALI1bhuzqXJ39DO3TOcmZyDw7dN1IKnRQTxGgCu5keCZko/9391eZtqCS8tED/nnjj hO6me+Czimoow== Message-ID: <238ab437-06b1-43ef-86bb-9341c02040b1@kernel.org> Date: Wed, 8 Apr 2026 14:17:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC V1 07/16] arm64/mm: Convert READ_ONCE() as p4dp_get() while accessing P4D To: Anshuman Khandual , linux-arm-kernel@lists.infradead.org Cc: Catalin Marinas , Will Deacon , Ryan Roberts , Mark Rutland , Lorenzo Stoakes , Andrew Morton , Mike Rapoport , Linu Cherian , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com References: <20260224051153.3150613-1-anshuman.khandual@arm.com> <20260224051153.3150613-8-anshuman.khandual@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260408_051728_218396_F054E3F9 X-CRM114-Status: GOOD ( 18.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2/24/26 06:11, Anshuman Khandual wrote: > Convert all READ_ONCE() based P4D accesses as p4dp_get() instead which will > support both D64 and D128 translation regime going forward. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Ryan Roberts > Cc: Mark Rutland > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Cc: kasan-dev@googlegroups.com > Signed-off-by: Anshuman Khandual > --- [...] > static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index a80d06db4de6..16ae11b29f66 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -354,7 +354,7 @@ static int alloc_init_pud(p4d_t *p4dp, unsigned long addr, unsigned long end, > { > int ret = 0; > unsigned long next; > - p4d_t p4d = READ_ONCE(*p4dp); > + p4d_t p4d = p4dp_get(p4dp); > pud_t *pudp; > > if (p4d_none(p4d)) { > @@ -443,7 +443,7 @@ static int alloc_init_p4d(pgd_t *pgdp, unsigned long addr, unsigned long end, > } > > do { > - p4d_t old_p4d = READ_ONCE(*p4dp); > + p4d_t old_p4d = p4dp_get(p4dp); > > next = p4d_addr_end(addr, end); > > @@ -453,7 +453,7 @@ static int alloc_init_p4d(pgd_t *pgdp, unsigned long addr, unsigned long end, > goto out; > > BUG_ON(p4d_val(old_p4d) != 0 && > - p4d_val(old_p4d) != READ_ONCE(p4d_val(*p4dp))); > + p4d_val(old_p4d) != (p4d_val(p4dp_get(p4dp)))); Same here, while at it remove the BUG_ON. (see below) > > phys += next - addr; > } while (p4dp++, addr = next, addr != end); > @@ -1541,7 +1541,7 @@ static void unmap_hotplug_p4d_range(pgd_t *pgdp, unsigned long addr, > do { > next = p4d_addr_end(addr, end); > p4dp = p4d_offset(pgdp, addr); > - p4d = READ_ONCE(*p4dp); > + p4d = p4dp_get(p4dp); > if (p4d_none(p4d)) > continue; > > @@ -1703,7 +1703,7 @@ static void free_empty_p4d_table(pgd_t *pgdp, unsigned long addr, > do { > next = p4d_addr_end(addr, end); > p4dp = p4d_offset(pgdp, addr); > - p4d = READ_ONCE(*p4dp); > + p4d = p4dp_get(p4dp); > if (p4d_none(p4d)) > continue; > > @@ -1724,7 +1724,7 @@ static void free_empty_p4d_table(pgd_t *pgdp, unsigned long addr, > */ > p4dp = p4d_offset(pgdp, 0UL); > for (i = 0; i < PTRS_PER_P4D; i++) { > - if (!p4d_none(READ_ONCE(p4dp[i]))) > + if (!p4d_none(p4dp_get(p4dp + i))) > return; > } > > @@ -2258,4 +2258,21 @@ int pmdp_test_and_clear_young(struct vm_area_struct *vma, > } > #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */ > > +#if CONFIG_PGTABLE_LEVELS > 3 > +phys_addr_t pud_offset_phys(p4d_t *p4dp, unsigned long addr) > +{ > + p4d_t p4d = p4dp_get(p4dp); > + > + BUG_ON(!pgtable_l4_enabled()); Heh, while at it, convert that to a VM_WARN_ON_ONCE() or anything else that is not a BUG. I strongly assume CONFIG_DEBUG_VM checks are sufficient. > + > + return p4d_page_paddr(p4d) + pud_index(addr) * sizeof(pud_t); > +} > + -- Cheers, David