From: David Hildenbrand <david@redhat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Wei Yang <richard.weiyang@gmail.com>
Cc: akpm@linux-foundation.org, riel@surriel.com,
Liam.Howlett@oracle.com, vbabka@suse.cz, harry.yoo@oracle.com,
linux-mm@kvack.org
Subject: Re: [PATCH 2/3] mm/rmap: could be partially_mapped only after no entire map
Date: Sat, 16 Aug 2025 08:31:59 +0200 [thread overview]
Message-ID: <15ccbbb0-8ebc-4c50-a1c8-fbe5416ecf46@redhat.com> (raw)
In-Reply-To: <458c4ea9-1e33-4159-a545-6ad2c5b81add@lucifer.local>
On 15.08.25 12:08, Lorenzo Stoakes wrote:
> On Fri, Aug 15, 2025 at 08:49:42AM +0000, Wei Yang wrote:
>> If it is not the last entire map, we are sure the folio is not partially
>> mapped.
>>
>> Move the check when there is no entire map.
>>
>
> This one I don't like, you're having to sit and think about why it is that
> this would be the case, vs. just unconditionally doing it.
>
> Again, as mentioned on previous series, just because we could do something
> doesn't mean we should, unless there's statistically reliable perf data on
> something real-world indicating we _must_, code clarity absolutely beats
> everything else on importance.
>
> So yeah, sorry but no to this patch, please resend with just the two
> reviewed (unless David radically disagrees with me :)
The compiler can figure out that "nr == 0" if the "if (last)" branch is
not taken.
So I tend to prefer keeping it as is.
--
Cheers
David / dhildenb
next prev parent reply other threads:[~2025-08-16 6:32 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-15 8:49 [PATCH 0/3] mm/rmap: small cleanup for __folio_remove_rmap() Wei Yang
2025-08-15 8:49 ` [PATCH 1/3] mm/rmap: not necessary to mask off FOLIO_PAGES_MAPPED Wei Yang
2025-08-15 9:38 ` Lorenzo Stoakes
2025-08-16 0:33 ` Wei Yang
2025-08-16 6:29 ` David Hildenbrand
2025-08-15 8:49 ` [PATCH 2/3] mm/rmap: could be partially_mapped only after no entire map Wei Yang
2025-08-15 10:08 ` Lorenzo Stoakes
2025-08-16 6:31 ` David Hildenbrand [this message]
2025-08-16 9:06 ` Wei Yang
2025-08-16 9:16 ` David Hildenbrand
2025-08-16 10:05 ` Giorgi Tchankvetadze
2025-08-16 10:32 ` David Hildenbrand
2025-08-16 14:03 ` Wei Yang
2025-08-15 8:49 ` [PATCH 3/3] mm/rmap: use folio_large_nr_pages() when we are sure it is a large folio Wei Yang
2025-08-15 10:04 ` Lorenzo Stoakes
2025-08-16 6:32 ` David Hildenbrand
2025-08-15 10:11 ` [PATCH 0/3] mm/rmap: small cleanup for __folio_remove_rmap() Lorenzo Stoakes
2025-08-16 0:36 ` Wei Yang
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