linux-kernel - Re: [PATCH] mm: memory-failure: remove unneeded page state check in shake

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Date:   Mon, 26 Jun 2023 09:43:44 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Naoya Horiguchi <naoya.horiguchi@...ux.dev>
CC:     <akpm@...ux-foundation.org>, <naoya.horiguchi@....com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH] mm: memory-failure: remove unneeded page state check in
 shake_page()

On 2023/6/26 8:52, Naoya Horiguchi wrote:
> On Sun, Jun 25, 2023 at 07:34:30PM +0800, Miaohe Lin wrote:
>> Remove unneeded PageLRU(p) and is_free_buddy_page(p) check as slab caches
>> are not shrunk now. This check can be added back when a lightweight range
>> based shrinker is available.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> 
> This looks to me a good cleanup because the result of
> "if (PageLRU(p) || is_free_buddy_page(p))" check is not used, so the check
> itself is unneeded.
> 
>> ---
>>  mm/memory-failure.c | 9 ++++-----
>>  1 file changed, 4 insertions(+), 5 deletions(-)
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index 5b663eca1f29..92f951df3e87 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -373,11 +373,10 @@ void shake_page(struct page *p)
>>  	if (PageHuge(p))
>>  		return;
>>  
>> -	if (!PageSlab(p)) {
>> -		lru_add_drain_all();
>> -		if (PageLRU(p) || is_free_buddy_page(p))
>> -			return;
>> -	}
>> +	if (PageSlab(p))
>> +		return;
>> +
>> +	lru_add_drain_all();
>>  
>>  	/*
>>  	 * TODO: Could shrink slab caches here if a lightweight range-based
> 
> I think that this TODO comment can be put together with "if (PageSlab)" block.

Thanks for your comment and advice. Do you mean something like below?

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5b663eca1f29..66e7b3ceaf2d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -372,17 +372,14 @@ void shake_page(struct page *p)
 {
        if (PageHuge(p))
                return;
-
-       if (!PageSlab(p)) {
-               lru_add_drain_all();
-               if (PageLRU(p) || is_free_buddy_page(p))
-                       return;
-       }
-
        /*
         * TODO: Could shrink slab caches here if a lightweight range-based
         * shrinker will be available.
         */
+       if (PageSlab(p))
+               return;
+
+       lru_add_drain_all();
 }
 EXPORT_SYMBOL_GPL(shake_page);

Thanks.