From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Vishal Moola (Oracle)" Subject: [PATCH 03/33] pgtable: Create struct ptdesc Date: Mon, 17 Apr 2023 13:50:18 -0700 Message-ID: <20230417205048.15870-4-vishal.moola@gmail.com> References: <20230417205048.15870-1-vishal.moola@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1681764769; x=1684356769; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ds3IS9TWlY4iXOF1Vygr3Q/N2fJxO0/Dzlxnv3cq6/0=; b=hr7pEt7A7XcPfK4WHrNDJyXTyW/f522/QxHB9K2NM6BmG8KnIlcSk7Prak06XFsubX Sjsu1MPagS5Ajy0wM6nwYZFly4hHrr9DYIrVTEdELHRdfsGo64oEk7qD+41S/NMObi8y l8A2tz8IWZ1X+Du4Mg5V1agW+uGCUPtQdgx1HioQtiEf01hZXw902OFYpkixEmc4936W rbvY3hq0N/ZSHnXC+KGydT6+ZrTUjCaNrxKIoD5OlWamJ5QPi1l2Tt7uz8xTA1Fp0QB2 97/hz5zZCcVfwzgfNZP+zBkRfPzWu3gB3ojY6/LKA9XIpl4tn1OEejbLEhRl9E9QH4p3 YC/g== In-Reply-To: <20230417205048.15870-1-vishal.moola@gmail.com> List-ID: Content-Type: text/plain; charset="us-ascii" To: Andrew Morton , Matthew Wilcox Cc: linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-openrisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, "Vishal Moola (Oracle)" Currently, page table information is stored within struct page. As part of simplifying struct page, create struct ptdesc for page table information. Signed-off-by: Vishal Moola (Oracle) --- include/linux/pgtable.h | 50 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 023918666dd4..7cc6ea057ee9 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -47,6 +47,56 @@ #define pmd_pgtable(pmd) pmd_page(pmd) #endif +/** + * struct ptdesc - Memory descriptor for page tables. + * @__page_flags: Same as page flags. Unused for page tables. + * @pt_list: List of used page tables. Used for s390 and x86. + * @_pt_pad_1: Padding that aliases with page's compound head. + * @pmd_huge_pte: Protected by ptdesc->ptl, used for THPs. + * @_pt_s390_gaddr: Aliases with page's mapping. Used for s390 gmap only. + * @pt_mm: Used for x86 pgds. + * @pt_frag_refcount: For fragmented page table tracking. Powerpc and s390 only. + * @ptl: Lock for the page table. + * + * This struct overlays struct page for now. Do not modify without a good + * understanding of the issues. + */ +struct ptdesc { + unsigned long __page_flags; + + union { + struct list_head pt_list; + struct { + unsigned long _pt_pad_1; + pgtable_t pmd_huge_pte; + }; + }; + unsigned long _pt_s390_gaddr; + + union { + struct mm_struct *pt_mm; + atomic_t pt_frag_refcount; + }; + +#if ALLOC_SPLIT_PTLOCKS + spinlock_t *ptl; +#else + spinlock_t ptl; +#endif +}; + +#define TABLE_MATCH(pg, pt) \ + static_assert(offsetof(struct page, pg) == offsetof(struct ptdesc, pt)) +TABLE_MATCH(flags, __page_flags); +TABLE_MATCH(compound_head, pt_list); +TABLE_MATCH(compound_head, _pt_pad_1); +TABLE_MATCH(mapping, _pt_s390_gaddr); +TABLE_MATCH(pmd_huge_pte, pmd_huge_pte); +TABLE_MATCH(pt_mm, pt_mm); +TABLE_MATCH(ptl, ptl); +#undef TABLE_MATCH +static_assert(sizeof(struct ptdesc) <= sizeof(struct page)); + /* * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD] * -- 2.39.2