From: Dev Jain <dev.jain@arm.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "David Hildenbrand (Arm)" <david@kernel.org>,
"Lorenzo Stoakes (Oracle)" <ljs@kernel.org>,
akpm@linux-foundation.org, axelrasmussen@google.com,
yuanchu@google.com, hughd@google.com, chrisl@kernel.org,
kasong@tencent.com, weixugc@google.com, Liam.Howlett@oracle.com,
vbabka@kernel.org, rppt@kernel.org, surenb@google.com,
mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com,
jannh@google.com, pfalcato@suse.de,
baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com,
nphamcs@gmail.com, bhe@redhat.com, baohua@kernel.org,
youngjun.park@lge.com, ziy@nvidia.com, kas@kernel.org,
yuzhao@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, ryan.roberts@arm.com,
anshuman.khandual@arm.com
Subject: Re: [PATCH 1/9] mm/rmap: make nr_pages signed in try_to_unmap_one
Date: Wed, 11 Mar 2026 10:24:22 +0530 [thread overview]
Message-ID: <5de784bd-d9f9-4331-9e20-6e50f6510e3d@arm.com> (raw)
In-Reply-To: <abARQsqJ0vjg2VTw@casper.infradead.org>
On 10/03/26 6:10 pm, Matthew Wilcox wrote:
> On Tue, Mar 10, 2026 at 01:53:21PM +0530, Dev Jain wrote:
>> So when I was playing around with the code, I noticed that passing
>> unsigned int nr_pages to add_mm_counter(-nr_pages) messes up things. Then
>
> Using int (whether signed or unsigned) to store nr_pages is a bad idea.
> Look how many people are asking about supporting PUD-sized folios.
> On an ARM 64k PAGE_SIZE machine, that's 2^26 pages which is uncomfortably
> close to 2^32. It'll only take one more level to exceed that, so, what,
> five to ten more years?
>
> Just use unsigned long everywhere now and save ourselves the grief later.
Thanks, let us do this.
next prev parent reply other threads:[~2026-03-11 4:54 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-10 7:30 [PATCH 0/9] mm/rmap: Optimize anonymous large folio unmapping Dev Jain
2026-03-10 7:30 ` [PATCH 1/9] mm/rmap: make nr_pages signed in try_to_unmap_one Dev Jain
2026-03-10 7:56 ` Lorenzo Stoakes (Oracle)
2026-03-10 8:06 ` David Hildenbrand (Arm)
2026-03-10 8:23 ` Dev Jain
2026-03-10 12:40 ` Matthew Wilcox
2026-03-11 4:54 ` Dev Jain [this message]
2026-03-10 7:30 ` [PATCH 2/9] mm/rmap: initialize nr_pages to 1 at loop start " Dev Jain
2026-03-10 8:10 ` Lorenzo Stoakes (Oracle)
2026-03-10 8:31 ` Dev Jain
2026-03-10 8:39 ` Lorenzo Stoakes (Oracle)
2026-03-10 8:43 ` Dev Jain
2026-03-10 7:30 ` [PATCH 3/9] mm/rmap: refactor lazyfree unmap commit path to commit_ttu_lazyfree_folio() Dev Jain
2026-03-10 8:19 ` Lorenzo Stoakes (Oracle)
2026-03-10 8:42 ` Dev Jain
2026-03-19 15:53 ` Lorenzo Stoakes (Oracle)
2026-03-10 7:30 ` [PATCH 4/9] mm/memory: Batch set uffd-wp markers during zapping Dev Jain
2026-03-10 7:30 ` [PATCH 5/9] mm/rmap: batch unmap folios belonging to uffd-wp VMAs Dev Jain
2026-03-10 8:34 ` Lorenzo Stoakes (Oracle)
2026-03-10 23:32 ` Barry Song
2026-03-11 4:14 ` Barry Song
2026-03-11 4:52 ` Dev Jain
2026-03-11 4:56 ` Dev Jain
2026-03-10 7:30 ` [PATCH 6/9] mm/swapfile: Make folio_dup_swap batchable Dev Jain
2026-03-10 8:27 ` Kairui Song
2026-03-10 8:46 ` Dev Jain
2026-03-10 8:49 ` Lorenzo Stoakes (Oracle)
2026-03-11 5:42 ` Dev Jain
2026-03-19 15:26 ` Lorenzo Stoakes (Oracle)
2026-03-19 16:47 ` Matthew Wilcox
2026-03-18 0:20 ` kernel test robot
2026-03-10 7:30 ` [PATCH 7/9] mm/swapfile: Make folio_put_swap batchable Dev Jain
2026-03-10 8:29 ` Kairui Song
2026-03-10 8:50 ` Dev Jain
2026-03-10 8:55 ` Lorenzo Stoakes (Oracle)
2026-03-18 1:04 ` kernel test robot
2026-03-10 7:30 ` [PATCH 8/9] mm/rmap: introduce folio_try_share_anon_rmap_ptes Dev Jain
2026-03-10 9:38 ` Lorenzo Stoakes (Oracle)
2026-03-11 8:09 ` Dev Jain
2026-03-12 8:19 ` Wei Yang
2026-03-19 15:47 ` Lorenzo Stoakes (Oracle)
2026-04-08 7:14 ` Dev Jain
2026-03-10 7:30 ` [PATCH 9/9] mm/rmap: enable batch unmapping of anonymous folios Dev Jain
2026-03-10 8:02 ` [PATCH 0/9] mm/rmap: Optimize anonymous large folio unmapping Lorenzo Stoakes (Oracle)
2026-03-10 9:28 ` Dev Jain
2026-03-10 12:59 ` Lance Yang
2026-03-11 8:11 ` Dev Jain
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