linux-kernel - Re: [PATCH v8 3/3] Revert "mm/memory-failure.c: fix race with changing page compound again"

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Date:   Sat, 9 Apr 2022 10:07:32 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Naoya Horiguchi <naoya.horiguchi@...ux.dev>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Yang Shi <shy828301@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        <linux-kernel@...r.kernel.org>, Linux-MM <linux-mm@...ck.org>
Subject: Re: [PATCH v8 3/3] Revert "mm/memory-failure.c: fix race with
 changing page compound again"

On 2022/4/8 21:53, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@....com>
> 
> Reverts commit 888af2701db7 ("mm/memory-failure.c: fix race with
> changing page compound again") because now we fetch the page refcount
> under hugetlb_lock in try_memory_failure_hugetlb() so that the race
> check is no longer necessary.
> 

Thanks a lot.
Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>

> Suggested-by: Miaohe Lin <linmiaohe@...wei.com>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
> ---
>  include/linux/mm.h      |  1 -
>  include/ras/ras_event.h |  1 -
>  mm/memory-failure.c     | 11 -----------
>  3 files changed, 13 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 9f44254af8ce..d446e834a3e5 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3251,7 +3251,6 @@ enum mf_action_page_type {
>  	MF_MSG_BUDDY,
>  	MF_MSG_DAX,
>  	MF_MSG_UNSPLIT_THP,
> -	MF_MSG_DIFFERENT_PAGE_SIZE,
>  	MF_MSG_UNKNOWN,
>  };
>  
> diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h
> index 1e694fd239b9..d0337a41141c 100644
> --- a/include/ras/ras_event.h
> +++ b/include/ras/ras_event.h
> @@ -374,7 +374,6 @@ TRACE_EVENT(aer_event,
>  	EM ( MF_MSG_BUDDY, "free buddy page" )				\
>  	EM ( MF_MSG_DAX, "dax page" )					\
>  	EM ( MF_MSG_UNSPLIT_THP, "unsplit thp" )			\
> -	EM ( MF_MSG_DIFFERENT_PAGE_SIZE, "different page size" )	\
>  	EMe ( MF_MSG_UNKNOWN, "unknown page" )
>  
>  /*
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index b2e32cdc3823..e2674532678b 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -733,7 +733,6 @@ static const char * const action_page_types[] = {
>  	[MF_MSG_BUDDY]			= "free buddy page",
>  	[MF_MSG_DAX]			= "dax page",
>  	[MF_MSG_UNSPLIT_THP]		= "unsplit thp",
> -	[MF_MSG_DIFFERENT_PAGE_SIZE]	= "different page size",
>  	[MF_MSG_UNKNOWN]		= "unknown page",
>  };
>  
> @@ -1605,16 +1604,6 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
>  		return res == MF_RECOVERED ? 0 : -EBUSY;
>  	}
>  
> -	/*
> -	 * The page could have changed compound pages due to race window.
> -	 * If this happens just bail out.
> -	 */
> -	if (!PageHuge(p) || compound_head(p) != head) {
> -		action_result(pfn, MF_MSG_DIFFERENT_PAGE_SIZE, MF_IGNORED);
> -		res = -EBUSY;
> -		goto out;
> -	}
> -
>  	page_flags = head->flags;
>  
>  	/*
>