linux-kernel - Re: [PATCH 05/23] x86, kaiser: unmap kernel from userspace page tables (core patch)

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Message-ID: <10ed0bc4-5f98-b771-5020-12838923b0ca@linux.intel.com>
Date:   Fri, 5 Jan 2018 23:51:38 -0800
From:   Dave Hansen <dave.hansen@...ux.intel.com>
To:     Hanjun Guo <guohanjun@...wei.com>, Jiri Kosina <jikos@...nel.org>
Cc:     Yisheng Xie <xieyisheng1@...wei.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, richard.fellner@...dent.tugraz.at,
        moritz.lipp@...k.tugraz.at, daniel.gruss@...k.tugraz.at,
        michael.schwarz@...k.tugraz.at, luto@...nel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        keescook@...gle.com, hughd@...gle.com, x86@...nel.org,
        Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [PATCH 05/23] x86, kaiser: unmap kernel from userspace page
 tables (core patch)

On 01/05/2018 10:28 PM, Hanjun Guo wrote:
>> +
>>  	p4d = p4d_alloc(&tboot_mm, pgd, vaddr);
> Seems pgd will be re-set after p4d_alloc(), so should
> we put the code behind (or after pud_alloc())?

<sigh> Yes, it has to go below where the PGD actually gets set which is
after pud_alloc().  You can put it anywhere later in the function.