From patchwork Mon May 1 19:27:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vishal Moola X-Patchwork-Id: 13227989 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 D413EC77B73 for ; Mon, 1 May 2023 19:28:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=s6FRipzBPgZvpqcCrq3K/+zd389RSRlWzLveE+3ndwY=; b=qinBe84iChdUIM 3LV60FR22AoOWxGnr1q+MmIb3V4QD51Y2G6PTrbplnTZFG4MqDtZzHqwuDb6IXx+BXDKMDcrCf3GJ MDQKp1RCrurad5E6EuZLaehnwTfwMO4DsodgmYaoAtdr6RpCNb6uTE/LHdRWq3kerG5oyY/2GUpRb CN3radMzIMCPRdYU1mj/6LwKpw+ywFa5+MtQMjuVtuc4kTQ9U4IVkU55Coy6r/BLkMNS2v/QY6pB2 uVdNGfvsGygIvVSUT3h1V6r7EnYCVTWRzDQr8A10jUAU6tp1Ymw7KsqkY2cVUQ3p/B0VEko8ouKNj LqPECEgCAGc/9wq3q0xA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1ptZCY-00Gh9f-2t; Mon, 01 May 2023 19:28:46 +0000 Received: from mail-pg1-x529.google.com ([2607:f8b0:4864:20::529]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1ptZCS-00Gh2f-2H; Mon, 01 May 2023 19:28:42 +0000 Received: by mail-pg1-x529.google.com with SMTP id 41be03b00d2f7-51452556acdso1820132a12.2; Mon, 01 May 2023 12:28:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1682969319; x=1685561319; 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=bmbsS8DkaHNij/v9bdafzBlktB7f+f7NAeK2Q02GvbI=; b=B4azYqsU+PZdNT5sPYRuRynEP/yG+nnQZzCwWNiJuBYZMp7zK7WPiFNkyYATyiWLs9 KXu3O4UXjROzHmg5BH+SgHHBIK4HaE73RnqEPc9ZoVRSl4Uh4CCXlTE9MpnCo1Ir9cR5 1tT0IRumxWPV12suNOkG+VwHWOIH3Na7v0j8RESqGnAScgYPrOMUDDIHfUYdpmcQFIY7 vF1i0igsbLRBnZPi2HEPlzfFt+R0Rd+c2dVX9RoHx/GLiWbMDfrtbVlk0iN4TeEGJT4d 1bO8trvKRg+pq0Q4NgCg3JPagFS7MkJj/4qfBc8P2r4TUch12xgUcUg4F69rFfadNKuw 8vIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682969319; x=1685561319; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=bmbsS8DkaHNij/v9bdafzBlktB7f+f7NAeK2Q02GvbI=; b=I7L0LxAt7W+qgKVPVLXMewIK0NXMeseEimxjeMkxNpv3txLMpkut8+QFBGg8P51olr ijdYynZw6ZR5jO0UVr9CYmH9wXWZW36rIoXBda9Y1UwmdpZY5zWZe6SLXMAdt9U7NKyP i2xk6rAriPFpG5m0mAOXUUmLwiGdFL3F4PvyCAsLam89Om8T5uRVWAH+HXJ8ThEK5+GX b5Kj8A6NVcKWl5QS7wsGC5S0bqmTj6F4ocBJn/F6jdqis9/eGj0osK9musAtphm7VKtY pmIHRY/sGKTra/D312/I0VRS+c8wHIYyErEZzWaPBv+nz3Ic2gvAEzpRtPXmW+XfIuzb PklQ== X-Gm-Message-State: AC+VfDy1KKncD3Cr1eseYQ71rJgp9PFT2ZICej9ef+Tkd2IjG3y1FUN1 +8KJLto/v/tPYUl3UBZdS0Y= X-Google-Smtp-Source: ACHHUZ4E/JVh2DFvUW/bEZgIHPiMJ+Zfpw7pvXWZYNeWA42FHZxnOhQrWiIO3kxV0xxzCmUatMgqYw== X-Received: by 2002:a17:902:8c91:b0:1a9:2b7f:a594 with SMTP id t17-20020a1709028c9100b001a92b7fa594mr13894676plo.29.1682969318714; Mon, 01 May 2023 12:28:38 -0700 (PDT) Received: from fedora.hsd1.ca.comcast.net ([2601:644:937f:7f20::9a2c]) by smtp.googlemail.com with ESMTPSA id u8-20020a170902bf4800b0019c13d032d8sm18175622pls.253.2023.05.01.12.28.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 May 2023 12:28:38 -0700 (PDT) From: "Vishal Moola (Oracle)" 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)" , David Hildenbrand , Claudio Imbrenda Subject: [PATCH v2 03/34] s390: Use pt_frag_refcount for pagetables Date: Mon, 1 May 2023 12:27:58 -0700 Message-Id: <20230501192829.17086-4-vishal.moola@gmail.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230501192829.17086-1-vishal.moola@gmail.com> References: <20230501192829.17086-1-vishal.moola@gmail.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230501_122840_775172_76927465 X-CRM114-Status: GOOD ( 18.62 ) X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org s390 currently uses _refcount to identify fragmented page tables. The page table struct already has a member pt_frag_refcount used by powerpc, so have s390 use that instead of the _refcount field as well. This improves the safety for _refcount and the page table tracking. This also allows us to simplify the tracking since we can once again use the lower byte of pt_frag_refcount instead of the upper byte of _refcount. Signed-off-by: Vishal Moola (Oracle) --- arch/s390/mm/pgalloc.c | 38 +++++++++++++++----------------------- 1 file changed, 15 insertions(+), 23 deletions(-) diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c index 66ab68db9842..6b99932abc66 100644 --- a/arch/s390/mm/pgalloc.c +++ b/arch/s390/mm/pgalloc.c @@ -182,20 +182,17 @@ void page_table_free_pgste(struct page *page) * As follows from the above, no unallocated or fully allocated parent * pages are contained in mm_context_t::pgtable_list. * - * The upper byte (bits 24-31) of the parent page _refcount is used + * The lower byte (bits 0-7) of the parent page pt_frag_refcount is used * for tracking contained 2KB-pgtables and has the following format: * * PP AA - * 01234567 upper byte (bits 24-31) of struct page::_refcount + * 01234567 upper byte (bits 0-7) of struct page::pt_frag_refcount * || || * || |+--- upper 2KB-pgtable is allocated * || +---- lower 2KB-pgtable is allocated * |+------- upper 2KB-pgtable is pending for removal * +-------- lower 2KB-pgtable is pending for removal * - * (See commit 620b4e903179 ("s390: use _refcount for pgtables") on why - * using _refcount is possible). - * * When 2KB-pgtable is allocated the corresponding AA bit is set to 1. * The parent page is either: * - added to mm_context_t::pgtable_list in case the second half of the @@ -243,11 +240,12 @@ unsigned long *page_table_alloc(struct mm_struct *mm) if (!list_empty(&mm->context.pgtable_list)) { page = list_first_entry(&mm->context.pgtable_list, struct page, lru); - mask = atomic_read(&page->_refcount) >> 24; + mask = atomic_read(&page->pt_frag_refcount); /* * The pending removal bits must also be checked. * Failure to do so might lead to an impossible - * value of (i.e 0x13 or 0x23) written to _refcount. + * value of (i.e 0x13 or 0x23) written to + * pt_frag_refcount. * Such values violate the assumption that pending and * allocation bits are mutually exclusive, and the rest * of the code unrails as result. That could lead to @@ -259,8 +257,8 @@ unsigned long *page_table_alloc(struct mm_struct *mm) bit = mask & 1; /* =1 -> second 2K */ if (bit) table += PTRS_PER_PTE; - atomic_xor_bits(&page->_refcount, - 0x01U << (bit + 24)); + atomic_xor_bits(&page->pt_frag_refcount, + 0x01U << bit); list_del(&page->lru); } } @@ -281,12 +279,12 @@ unsigned long *page_table_alloc(struct mm_struct *mm) table = (unsigned long *) page_to_virt(page); if (mm_alloc_pgste(mm)) { /* Return 4K page table with PGSTEs */ - atomic_xor_bits(&page->_refcount, 0x03U << 24); + atomic_xor_bits(&page->pt_frag_refcount, 0x03U); memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); } else { /* Return the first 2K fragment of the page */ - atomic_xor_bits(&page->_refcount, 0x01U << 24); + atomic_xor_bits(&page->pt_frag_refcount, 0x01U); memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE); spin_lock_bh(&mm->context.lock); list_add(&page->lru, &mm->context.pgtable_list); @@ -323,22 +321,19 @@ void page_table_free(struct mm_struct *mm, unsigned long *table) * will happen outside of the critical section from this * function or from __tlb_remove_table() */ - mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24)); - mask >>= 24; + mask = atomic_xor_bits(&page->pt_frag_refcount, 0x11U << bit); if (mask & 0x03U) list_add(&page->lru, &mm->context.pgtable_list); else list_del(&page->lru); spin_unlock_bh(&mm->context.lock); - mask = atomic_xor_bits(&page->_refcount, 0x10U << (bit + 24)); - mask >>= 24; + mask = atomic_xor_bits(&page->pt_frag_refcount, 0x10U << bit); if (mask != 0x00U) return; half = 0x01U << bit; } else { half = 0x03U; - mask = atomic_xor_bits(&page->_refcount, 0x03U << 24); - mask >>= 24; + mask = atomic_xor_bits(&page->pt_frag_refcount, 0x03U); } page_table_release_check(page, table, half, mask); @@ -368,8 +363,7 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, * outside of the critical section from __tlb_remove_table() or from * page_table_free() */ - mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24)); - mask >>= 24; + mask = atomic_xor_bits(&page->pt_frag_refcount, 0x11U << bit); if (mask & 0x03U) list_add_tail(&page->lru, &mm->context.pgtable_list); else @@ -391,14 +385,12 @@ void __tlb_remove_table(void *_table) return; case 0x01U: /* lower 2K of a 4K page table */ case 0x02U: /* higher 2K of a 4K page table */ - mask = atomic_xor_bits(&page->_refcount, mask << (4 + 24)); - mask >>= 24; + mask = atomic_xor_bits(&page->pt_frag_refcount, mask << 4); if (mask != 0x00U) return; break; case 0x03U: /* 4K page table with pgstes */ - mask = atomic_xor_bits(&page->_refcount, 0x03U << 24); - mask >>= 24; + mask = atomic_xor_bits(&page->pt_frag_refcount, 0x03U); break; }