linux-kernel - Re: [PATCH v22 1/4] mm: add MAP_DROPPABLE for designating always lazily freeable mappings

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Message-ID: <ac230cd8-11b0-48f2-94dd-6195967c08e9@redhat.com>
Date: Thu, 11 Jul 2024 22:59:18 +0200
From: David Hildenbrand <david@...hat.com>
To: "Jason A. Donenfeld" <Jason@...c4.com>, Yu Zhao <yuzhao@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
 linux-kernel@...r.kernel.org, patches@...ts.linux.dev, tglx@...utronix.de,
 linux-crypto@...r.kernel.org, linux-api@...r.kernel.org, x86@...nel.org,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Adhemerval Zanella Netto <adhemerval.zanella@...aro.org>,
 Carlos O'Donell <carlos@...hat.com>, Florian Weimer <fweimer@...hat.com>,
 Arnd Bergmann <arnd@...db.de>, Jann Horn <jannh@...gle.com>,
 Christian Brauner <brauner@...nel.org>,
 David Hildenbrand <dhildenb@...hat.com>, linux-mm@...ck.org
Subject: Re: [PATCH v22 1/4] mm: add MAP_DROPPABLE for designating always
 lazily freeable mappings

On 11.07.24 22:20, Jason A. Donenfeld wrote:
> Hi David,
> 
> On Thu, Jul 11, 2024 at 01:49:42PM -0600, Yu Zhao wrote:
>> On Thu, Jul 11, 2024 at 1:20 PM David Hildenbrand <david@...hat.com> wrote:
>>>> -       /* dirty lazyfree */
>>>> -       if (type == LRU_GEN_FILE && folio_test_anon(folio) && folio_test_dirty(folio)) {
>>>> -               success = lru_gen_del_folio(lruvec, folio, true);
>>>> -               VM_WARN_ON_ONCE_FOLIO(!success, folio);
>>>> -               folio_set_swapbacked(folio);
>>>> -               lruvec_add_folio_tail(lruvec, folio);
>>>> -               return true;
>>>> -       }
> 
>> This is an optimization to avoid an unnecessary trip to
>> shrink_folio_list(), so it's safe to delete the entire 'if' block, and
>> that would be preferable than leaving a dangling 'if'.
> 
> Alright, I'll just remove that entire chunk then, for v+1 of this patch?
> That sounds prettttty okay.

Yes!

-- 
Cheers,

David / dhildenb