From patchwork Mon Mar 17 14:16:51 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 14019501 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 0C5FEC28B30 for ; Mon, 17 Mar 2025 14:25:24 +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: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=FkrrTiKic5g/SkGADpTJcYzWJvDsKPZ0Ua0I8vQ0aUw=; b=YByge+CCZ2r9NCZO/Vp4/TPiqg 9s/ZiPOGxFAdFhUrZqg+9YwobtpcXIIR4OSDWFSm3sYYrTGdaGlkdGDI4ZVN3ZBTnUDufpj/ogxMm BMTH8BFKEhTHzxFpiw334pKoZfWwxPUeUfWsJAvLv7KYA7EhhY2Fb6FRcU3/hbPJLSnVHcMZx/tK4 OM3bxvEPGPbCXLaYtr2BN7zq7S9Sr6c/HU8xFcgzwo1ndJm9lk1QsjRSIiinIdgSAE2M3wJzbUOrr KF2eIlwQzKVk41IeKLKo03hf3oNvCVQgatGkWKxnZVDnjdgb34XmyGgX8iJBl4dVMXEprEWz0lgCP jdiLHssg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tuBOy-00000002voA-14Wo; Mon, 17 Mar 2025 14:25:12 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tuBLY-00000002uIe-19gO; Mon, 17 Mar 2025 14:21:41 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CF25D22FA; Mon, 17 Mar 2025 07:21:48 -0700 (PDT) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A78843F63F; Mon, 17 Mar 2025 07:21:35 -0700 (PDT) From: Kevin Brodsky To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Albert Ou , Andreas Larsson , Andrew Morton , Catalin Marinas , Dave Hansen , "David S. Miller" , Geert Uytterhoeven , Linus Walleij , Madhavan Srinivasan , Mark Rutland , Matthew Wilcox , Michael Ellerman , "Mike Rapoport (IBM)" , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Qi Zheng , Ryan Roberts , Will Deacon , Yang Shi , linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-openrisc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org Subject: [PATCH 02/11] mm: Call ctor/dtor for kernel PTEs Date: Mon, 17 Mar 2025 14:16:51 +0000 Message-ID: <20250317141700.3701581-3-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250317141700.3701581-1-kevin.brodsky@arm.com> References: <20250317141700.3701581-1-kevin.brodsky@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250317_072140_395792_D86EAA13 X-CRM114-Status: GOOD ( 18.36 ) 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 Since [1], constructors/destructors are expected to be called for all page table pages, at all levels and for both user and kernel pgtables. There is however one glaring exception: kernel PTEs are managed via separate helpers (pte_alloc_kernel/pte_free_kernel), which do not call the [cd]tor, at least not in the generic implementation. The most obvious reason for this anomaly is that init_mm is special-cased not to use split page table locks. As a result calling ptlock_init() for PTEs associated with init_mm would be wasteful, potentially resulting in dynamic memory allocation. However, pgtable [cd]tors perform other actions - currently related to accounting/statistics, and potentially more functionally significant in the future. Now that pagetable_pte_ctor() is passed the associated mm, we can make it skip the call to ptlock_init() for init_mm; this allows us to call the ctor from pte_alloc_one_kernel() too. This is matched by a call to the pgtable destructor in pte_free_kernel(); no special-casing is needed on that path, as ptlock_free() is already called unconditionally. (ptlock_free() is a no-op unless a ptlock was allocated for the given PTP.) This patch ensures that all architectures that rely on call the [cd]tor for kernel PTEs. pte_free_kernel() cannot be overridden so changing the generic implementation is sufficient. pte_alloc_one_kernel() can be overridden using __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL, and a few architectures implement it by calling the page allocator directly. We amend those so that they call the generic __pte_alloc_one_kernel() instead, if possible, ensuring that the ctor is called. A few architectures do not use ; those will be taken care of separately. [1] https://lore.kernel.org/linux-mm/20250103184415.2744423-1-kevin.brodsky@arm.com/ Signed-off-by: Kevin Brodsky --- arch/csky/include/asm/pgalloc.h | 2 +- arch/microblaze/mm/pgtable.c | 2 +- arch/openrisc/mm/ioremap.c | 2 +- include/asm-generic/pgalloc.h | 7 ++++++- include/linux/mm.h | 2 +- 5 files changed, 10 insertions(+), 5 deletions(-) diff --git a/arch/csky/include/asm/pgalloc.h b/arch/csky/include/asm/pgalloc.h index bf8400c28b5a..288dca0d160a 100644 --- a/arch/csky/include/asm/pgalloc.h +++ b/arch/csky/include/asm/pgalloc.h @@ -29,7 +29,7 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm) pte_t *pte; unsigned long i; - pte = (pte_t *) __get_free_page(GFP_KERNEL); + pte = __pte_alloc_one_kernel(mm); if (!pte) return NULL; diff --git a/arch/microblaze/mm/pgtable.c b/arch/microblaze/mm/pgtable.c index 9f73265aad4e..e96dd1b7aba4 100644 --- a/arch/microblaze/mm/pgtable.c +++ b/arch/microblaze/mm/pgtable.c @@ -245,7 +245,7 @@ unsigned long iopa(unsigned long addr) __ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm) { if (mem_init_done) - return (pte_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO); + return __pte_alloc_one_kernel(mm); else return memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE, MEMBLOCK_LOW_LIMIT, diff --git a/arch/openrisc/mm/ioremap.c b/arch/openrisc/mm/ioremap.c index 8e63e86251ca..3b352f97fecb 100644 --- a/arch/openrisc/mm/ioremap.c +++ b/arch/openrisc/mm/ioremap.c @@ -36,7 +36,7 @@ pte_t __ref *pte_alloc_one_kernel(struct mm_struct *mm) pte_t *pte; if (likely(mem_init_done)) { - pte = (pte_t *)get_zeroed_page(GFP_KERNEL); + pte = __pte_alloc_one_kernel(mm); } else { pte = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE); } diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h index e164ca66f0f6..3c8ec3bfea44 100644 --- a/include/asm-generic/pgalloc.h +++ b/include/asm-generic/pgalloc.h @@ -23,6 +23,11 @@ static inline pte_t *__pte_alloc_one_kernel_noprof(struct mm_struct *mm) if (!ptdesc) return NULL; + if (!pagetable_pte_ctor(mm, ptdesc)) { + pagetable_free(ptdesc); + return NULL; + } + return ptdesc_address(ptdesc); } #define __pte_alloc_one_kernel(...) alloc_hooks(__pte_alloc_one_kernel_noprof(__VA_ARGS__)) @@ -48,7 +53,7 @@ static inline pte_t *pte_alloc_one_kernel_noprof(struct mm_struct *mm) */ static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte) { - pagetable_free(virt_to_ptdesc(pte)); + pagetable_dtor_free(virt_to_ptdesc(pte)); } /** diff --git a/include/linux/mm.h b/include/linux/mm.h index d92c16f6cfa2..ee31ffd7ead2 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3018,7 +3018,7 @@ static inline void pagetable_dtor_free(struct ptdesc *ptdesc) static inline bool pagetable_pte_ctor(struct mm_struct *mm, struct ptdesc *ptdesc) { - if (!ptlock_init(ptdesc)) + if (mm != &init_mm && !ptlock_init(ptdesc)) return false; __pagetable_ctor(ptdesc); return true;