linux-kernel - Re: [PATCH v2 01/13] mm/memory-failure: simplify put_ref

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Date: Fri, 7 Jun 2024 11:28:39 +0800
From: Miaohe Lin <linmiaohe@...wei.com>
To: Kefeng Wang <wangkefeng.wang@...wei.com>
CC: <nao.horiguchi@...il.com>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>, <linux-edac@...r.kernel.org>,
	<akpm@...ux-foundation.org>, <tony.luck@...el.com>, <bp@...en8.de>
Subject: Re: [PATCH v2 01/13] mm/memory-failure: simplify put_ref_page()

On 2024/6/6 14:46, Kefeng Wang wrote:
> 
> 
> On 2024/6/6 14:32, Miaohe Lin wrote:
>> Remove unneeded page != NULL check. pfn_to_page() won't return NULL.
>> No functional change intended.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
>> ---
>>   mm/memory-failure.c | 6 +-----
>>   1 file changed, 1 insertion(+), 5 deletions(-)
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index f679b579d45d..2e6038c73119 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -2120,14 +2120,10 @@ static inline unsigned long folio_free_raw_hwp(struct folio *folio, bool flag)
>>   /* Drop the extra refcount in case we come from madvise() */
>>   static void put_ref_page(unsigned long pfn, int flags)
> 
> Since all calllers have a valid page，better to pass the page instead of pfn?

Seems not. put_ref_page() called above memory_failure_dev_pagemap() seems don't have a valid page yet.
Also page might be NULL when calling put_ref_page() in soft_offline_page(). So it should be better to
still pass pfn. Or am I miss something?

Thanks.
.