From: Kiryl Shutsemau <kirill@shutemov.name>
To: ilya.gladyshev@linux.dev
Cc: ivgorbunov@me.com, Liam.Howlett@oracle.com,
akpm@linux-foundation.org, apopple@nvidia.com,
artem.kuzin@huawei.com, baolin.wang@linux.alibaba.com,
david@kernel.org, foxido@foxido.dev, harry.yoo@oracle.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
lorenzo.stoakes@oracle.com, mhocko@suse.com,
muchun.song@linux.dev, rppt@kernel.org, surenb@google.com,
torvalds@linuxfoundation.org, vbabka@suse.cz,
willy@infradead.org, yuzhao@google.com, ziy@nvidia.com,
pfalcato@suse.de
Subject: Re: [PATCH v3 1/2] mm: drop page refcount zero state semantics
Date: Thu, 4 Jun 2026 12:04:34 +0100 [thread overview]
Message-ID: <aiFZ57eRrCcWmS6E@thinkstation> (raw)
In-Reply-To: <7c28d766b007345f5f31ba9a086a3bffe95a013d@linux.dev>
On Thu, Jun 04, 2026 at 10:15:12AM +0000, ilya.gladyshev@linux.dev wrote:
> @@ -115,8 +120,14 @@ static inline void init_page_count(struct page *page)
> set_page_count(page, 1);
> }
>
> +static inline void set_page_count_as_frozen(struct page *page)
> +{
> + set_page_count(page, 0);
> +}
> +
This name is strange. Maybe something like init_page_count_frozen()?
And don't you want to update it in patch 2 to set the bit?
> static inline void page_ref_add(struct page *page, int nr)
> {
> + VM_BUG_ON(__page_count_is_frozen(page_count(page)));
Hm. These VM_BUG_ONs are useless after patch 2.
In patch 2, you make __page_count_is_frozen() check the frozen bit and
page_count() masks out frozen bit.
I guess you want to read raw ref number here, no?
And why not VM_BUG_ON_PAGE/FOLIO()?
> atomic_add(nr, &page->_refcount);
> if (page_ref_tracepoint_active(page_ref_mod))
> __page_ref_mod(page, nr);
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2026-06-04 11:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-04 10:13 [PATCH v3 0/2] mm: improve folio refcount scalability ilya.gladyshev
2026-06-04 10:15 ` [PATCH v3 1/2] mm: drop page refcount zero state semantics ilya.gladyshev
2026-06-04 11:04 ` Kiryl Shutsemau [this message]
2026-06-04 12:47 ` ilya.gladyshev
2026-06-04 10:15 ` [PATCH v3 2/2] mm: implement page refcount locking via dedicated bit ilya.gladyshev
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