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From: Andrew Morton <akpm@linux-foundation.org>
To: Yu Zhao <yuzhao@google.com>
Cc: Wei Xu <weixugc@google.com>, Brian Geffon <bgeffon@google.com>,
	Jan Alexander Steffens <heftig@archlinux.org>,
	Suleiman Souhlal <suleiman@google.com>,
	Axel Rasmussen <axelrasmussen@google.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm/mglru: reset page lru tier bits when activating
Date: Wed, 16 Oct 2024 15:55:50 -0700	[thread overview]
Message-ID: <20241016155550.9ff2ab4625c7f19b6be8b7e1@linux-foundation.org> (raw)
In-Reply-To: <CAOUHufb2nJ4-qEWrS_d0X_8FbLKR-+=OC3yNh1ExthKXiYYKHQ@mail.gmail.com>

On Tue, 15 Oct 2024 22:55:23 -0600 Yu Zhao <yuzhao@google.com> wrote:

> > @@ -257,7 +258,9 @@ static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio,
> >         gen = lru_gen_from_seq(seq);
> >         flags = (gen + 1UL) << LRU_GEN_PGOFF;
> >         /* see the comment on MIN_NR_GENS about PG_active */
> > -       set_mask_bits(&folio->flags, LRU_GEN_MASK | BIT(PG_active), flags);
> > +       mask = LRU_GEN_MASK | BIT(PG_active);
> > +       mask |= folio_test_active(folio) ? (LRU_REFS_MASK | LRU_REFS_FLAGS) : 0;
> 
> We shouldn't clear PG_workingset here because it can affect PSI
> accounting, if the activation is due to workingset refault.
> 
> Also, nit:
>   mask = LRU_GEN_MASK;
>   if (folio_test_active(folio))
>     mask |= LRU_REFS_MASK | BIT(PG_active) | BIT(PG_referenced);
> 

Thanks, I'll drop this version of this patch.

When resending, please include a full description of the userspace-visible
effects of the original flaw, thanks.


  reply	other threads:[~2024-10-16 22:55 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-14 22:12 Wei Xu
2024-10-14 23:27 ` Andrew Morton
2024-10-14 23:47   ` Wei Xu
2024-10-16  4:55 ` Yu Zhao
2024-10-16 22:55   ` Andrew Morton [this message]
2024-10-17 18:21     ` Wei Xu

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