linux-kernel - Re: [PATCH v5 2/6] userfaultfd: use kmap_local_page() in copy_huge_page_from

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Message-ID: <20230406213233.GC14244@monkey>
Date:   Thu, 6 Apr 2023 14:32:33 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Peng Zhang <zhangpeng362@...wei.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, willy@...radead.org,
        sidhartha.kumar@...cle.com, vishal.moola@...il.com,
        muchun.song@...ux.dev, wangkefeng.wang@...wei.com,
        sunnanyong@...wei.com
Subject: Re: [PATCH v5 2/6] userfaultfd: use kmap_local_page() in
 copy_huge_page_from_user()

On 03/31/23 17:39, Peng Zhang wrote:
> From: ZhangPeng <zhangpeng362@...wei.com>
> 
> kmap() and kmap_atomic() are being deprecated in favor of
> kmap_local_page() which is appropriate for any thread local context.[1]
> 
> Let's replace the kmap() and kmap_atomic() with kmap_local_page() in
> copy_huge_page_from_user(). When allow_pagefault is false, disable page
> faults to prevent potential deadlock.[2]
> 
> [1] https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com/
> [2] https://lkml.kernel.org/r/20221025220136.2366143-1-ira.weiny@intel.com
> 
> Signed-off-by: ZhangPeng <zhangpeng362@...wei.com>
> ---
>  mm/memory.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)

Thanks,

Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
-- 
Mike Kravetz