From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-f72.google.com (mail-ot1-f72.google.com [209.85.210.72]) by kanga.kvack.org (Postfix) with ESMTP id 552626B026D for ; Tue, 2 Oct 2018 07:05:42 -0400 (EDT) Received: by mail-ot1-f72.google.com with SMTP id s68so1055504ota.11 for ; Tue, 02 Oct 2018 04:05:42 -0700 (PDT) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id v3-v6si7354156oiv.195.2018.10.02.04.05.40 for ; Tue, 02 Oct 2018 04:05:41 -0700 (PDT) From: Will Deacon Subject: [PATCH v2 1/5] ioremap: Rework pXd_free_pYd_page() API Date: Tue, 2 Oct 2018 12:05:59 +0100 Message-Id: <1538478363-16255-2-git-send-email-will.deacon@arm.com> In-Reply-To: <1538478363-16255-1-git-send-email-will.deacon@arm.com> References: <1538478363-16255-1-git-send-email-will.deacon@arm.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: cpandya@codeaurora.org, toshi.kani@hpe.com, tglx@linutronix.de, mhocko@suse.com, akpm@linux-foundation.org, sean.j.christopherson@intel.com, Will Deacon The recently merged API for ensuring break-before-make on page-table entries when installing huge mappings in the vmalloc/ioremap region is fairly counter-intuitive, resulting in the arch freeing functions (e.g. pmd_free_pte_page()) being called even on entries that aren't present. This resulted in a minor bug in the arm64 implementation, giving rise to spurious VM_WARN messages. This patch moves the pXd_present() checks out into the core code, refactoring the callsites at the same time so that we avoid the complex conjunctions when determining whether or not we can put down a huge mapping. Cc: Chintan Pandya Cc: Toshi Kani Cc: Thomas Gleixner Cc: Michal Hocko Cc: Andrew Morton Suggested-by: Linus Torvalds Reviewed-by: Toshi Kani Signed-off-by: Will Deacon --- lib/ioremap.c | 56 ++++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 42 insertions(+), 14 deletions(-) diff --git a/lib/ioremap.c b/lib/ioremap.c index 517f5853ffed..6c72764af19c 100644 --- a/lib/ioremap.c +++ b/lib/ioremap.c @@ -76,6 +76,25 @@ static int ioremap_pte_range(pmd_t *pmd, unsigned long addr, return 0; } +static int ioremap_try_huge_pmd(pmd_t *pmd, unsigned long addr, + unsigned long end, phys_addr_t phys_addr, + pgprot_t prot) +{ + if (!ioremap_pmd_enabled()) + return 0; + + if ((end - addr) != PMD_SIZE) + return 0; + + if (!IS_ALIGNED(phys_addr, PMD_SIZE)) + return 0; + + if (pmd_present(*pmd) && !pmd_free_pte_page(pmd, addr)) + return 0; + + return pmd_set_huge(pmd, phys_addr, prot); +} + static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, phys_addr_t phys_addr, pgprot_t prot) { @@ -89,13 +108,8 @@ static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr, do { next = pmd_addr_end(addr, end); - if (ioremap_pmd_enabled() && - ((next - addr) == PMD_SIZE) && - IS_ALIGNED(phys_addr + addr, PMD_SIZE) && - pmd_free_pte_page(pmd, addr)) { - if (pmd_set_huge(pmd, phys_addr + addr, prot)) - continue; - } + if (ioremap_try_huge_pmd(pmd, addr, next, phys_addr + addr, prot)) + continue; if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot)) return -ENOMEM; @@ -103,6 +117,25 @@ static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr, return 0; } +static int ioremap_try_huge_pud(pud_t *pud, unsigned long addr, + unsigned long end, phys_addr_t phys_addr, + pgprot_t prot) +{ + if (!ioremap_pud_enabled()) + return 0; + + if ((end - addr) != PUD_SIZE) + return 0; + + if (!IS_ALIGNED(phys_addr, PUD_SIZE)) + return 0; + + if (pud_present(*pud) && !pud_free_pmd_page(pud, addr)) + return 0; + + return pud_set_huge(pud, phys_addr, prot); +} + static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, phys_addr_t phys_addr, pgprot_t prot) { @@ -116,13 +149,8 @@ static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr, do { next = pud_addr_end(addr, end); - if (ioremap_pud_enabled() && - ((next - addr) == PUD_SIZE) && - IS_ALIGNED(phys_addr + addr, PUD_SIZE) && - pud_free_pmd_page(pud, addr)) { - if (pud_set_huge(pud, phys_addr + addr, prot)) - continue; - } + if (ioremap_try_huge_pud(pud, addr, next, phys_addr + addr, prot)) + continue; if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot)) return -ENOMEM; -- 2.1.4