linux-kernel - Re: [PATCH v3 1/8] mm: Cleanup faultaround and finish

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Message-ID: <2ed7aff4-3c07-364f-838b-7342625b12a1@roeck-us.net>
Date:   Wed, 10 Feb 2021 06:57:15 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Will Deacon <will@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Jan Kara <jack@...e.cz>, Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Vinayak Menon <vinmenon@...eaurora.org>,
        Hugh Dickins <hughd@...gle.com>, kernel-team@...roid.com
Subject: Re: [PATCH v3 1/8] mm: Cleanup faultaround and finish_fault()
 codepaths

On 2/10/21 3:44 AM, Will Deacon wrote:
> On Tue, Feb 09, 2021 at 12:24:49PM -0800, Guenter Roeck wrote:
>> On Thu, Jan 14, 2021 at 05:59:27PM +0000, Will Deacon wrote:
>>> From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
>>>
>>> alloc_set_pte() has two users with different requirements: in the
>>> faultaround code, it called from an atomic context and PTE page table
>>> has to be preallocated. finish_fault() can sleep and allocate page table
>>> as needed.
>>>
>>> PTL locking rules are also strange, hard to follow and overkill for
>>> finish_fault().
>>>
>>> Let's untangle the mess. alloc_set_pte() has gone now. All locking is
>>> explicit.
>>>
>>> The price is some code duplication to handle huge pages in faultaround
>>> path, but it should be fine, having overall improvement in readability.
>>>
>>> Link: https://lore.kernel.org/r/20201229132819.najtavneutnf7ajp@box
>>> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
>>> [will: s/from from/from/ in comment; spotted by willy]
>>> Signed-off-by: Will Deacon <will@...nel.org>
>>> ---
>>>  fs/xfs/xfs_file.c       |   6 +-
>>>  include/linux/mm.h      |  12 ++-
>>>  include/linux/pgtable.h |  11 +++
>>>  mm/filemap.c            | 177 ++++++++++++++++++++++++++---------
>>>  mm/memory.c             | 199 ++++++++++++----------------------------
>>>  5 files changed, 213 insertions(+), 192 deletions(-)
>>>
>>
>> When building microblaze:mmu_defconfig:
>>
>> mm/filemap.c: In function 'filemap_map_pages':
>> mm/filemap.c:3153:3: error: implicit declaration of function 'update_mmu_cache'; did you mean 'update_mmu_tlb'?
>>
>> Bisect log attached.
> 
> Looks like a missing include.
> 
Indeed.

> Will
> 
> --->8
> 
>>>From 076f93117c067d5b6caab4773c6d6da130859cc4 Mon Sep 17 00:00:00 2001
> From: Will Deacon <will@...nel.org>
> Date: Wed, 10 Feb 2021 11:15:11 +0000
> Subject: [PATCH] mm: filemap: Fix microblaze build failure with
>  'mmu_defconfig'
> 
> Commit f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault()
> codepaths") added a call to 'update_mmu_cache()' in mm/filemap.c, which
> breaks the build for microblaze:
> 
>   | mm/filemap.c: In function 'filemap_map_pages':
>   | mm/filemap.c:3153:3: error: implicit declaration of function 'update_mmu_cache'; did you mean 'update_mmu_tlb'?
> 
> Include asm/tlbflush.h in mm/filemap.c to make sure that the function
> (or indeed, macro) is available.
> 
> Reported-by: Guenter Roeck <linux@...ck-us.net>
> Link: https://lore.kernel.org/r/20210209202449.GA104837@roeck-us.net
> Signed-off-by: Will Deacon <will@...nel.org>

Tested-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  mm/filemap.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index fb7a8d9b5603..2ca13227747b 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -43,6 +43,7 @@
>  #include <linux/ramfs.h>
>  #include <linux/page_idle.h>
>  #include <asm/pgalloc.h>
> +#include <asm/tlbflush.h>
>  #include "internal.h"
>  
>  #define CREATE_TRACE_POINTS
>