From: Dave Hansen <dave.hansen@intel.com>
To: "Singh, Brijesh" <brijesh.singh@amd.com>,
"x86@kernel.org" <x86@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Dan Williams <dan.j.williams@intel.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Lendacky, Thomas" <Thomas.Lendacky@amd.com>
Subject: Re: [PATCH v3] x86: mm: Do not use set_{pud,pmd}_safe when splitting the large page
Date: Wed, 17 Apr 2019 10:24:24 -0700 [thread overview]
Message-ID: <ae2c9081-f61c-a33a-67f0-2e05ef702e61@intel.com> (raw)
In-Reply-To: <20190417154102.22613-1-brijesh.singh@amd.com>
On 4/17/19 8:41 AM, Singh, Brijesh wrote:
> Changes since v2:
> - rename variable safe->init
> - rename __set_* -> set_*_init()
> - remame __*_populate -> *_populate_init()
"init" in this context really means "setting non-present PTEs is OK, but
changing present ones is not". It still doesn't do a great job of
conveying that because both the init=0 and init=1 variants are used
during init-time.
> +/*
> + * Create page table mapping for the physical memory for specific physical
> + * addresses. The virtual and physical addresses have to be aligned on PMD level
> + * down. It returns the last physical address mapped.
> + */
> +unsigned long __meminit
> +kernel_physical_mapping_init(unsigned long paddr_start,
> + unsigned long paddr_end,
> + unsigned long page_size_mask)
> +{
> + return __kernel_physical_mapping_init(paddr_start, paddr_end,
> + page_size_mask, true);
> +}
The comment here is missing one key point:
kernel_physical_mapping_init() can only be used to populate non-present
entries. It kinda infers that from "Create...", but I really think we
need to be explicit.
Anyway, it's better than it was, and it does fix a bug, so:
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
But please flesh out that comment if you do another version for some reason.
next prev parent reply other threads:[~2019-04-17 17:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-17 15:41 [PATCH v3] x86: mm: Do not use set_{pud,pmd}_safe when splitting the large page Singh, Brijesh
2019-04-17 17:24 ` Dave Hansen [this message]
2019-05-03 15:28 ` Singh, Brijesh
2019-05-09 11:04 ` [tip:x86/urgent] x86/mm: Do not use set_{pud, pmd}_safe() when splitting a " tip-bot for Brijesh Singh
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