From: Matthew Wilcox <willy@infradead.org>
To: Dev Jain <dev.jain@arm.com>
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: Tue, 10 Mar 2026 12:40:34 +0000 [thread overview]
Message-ID: <abARQsqJ0vjg2VTw@casper.infradead.org> (raw)
In-Reply-To: <04a7465b-ee69-479f-aaa4-ccdf3ae16805@arm.com>
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.
next prev parent reply other threads:[~2026-03-10 12:41 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 [this message]
2026-03-11 4:54 ` Dev Jain
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=abARQsqJ0vjg2VTw@casper.infradead.org \
--to=willy@infradead.org \
--cc=Liam.Howlett@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=anshuman.khandual@arm.com \
--cc=axelrasmussen@google.com \
--cc=baohua@kernel.org \
--cc=baolin.wang@linux.alibaba.com \
--cc=bhe@redhat.com \
--cc=chrisl@kernel.org \
--cc=david@kernel.org \
--cc=dev.jain@arm.com \
--cc=harry.yoo@oracle.com \
--cc=hughd@google.com \
--cc=jannh@google.com \
--cc=kas@kernel.org \
--cc=kasong@tencent.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=ljs@kernel.org \
--cc=mhocko@suse.com \
--cc=nphamcs@gmail.com \
--cc=pfalcato@suse.de \
--cc=riel@surriel.com \
--cc=rppt@kernel.org \
--cc=ryan.roberts@arm.com \
--cc=shikemeng@huaweicloud.com \
--cc=surenb@google.com \
--cc=vbabka@kernel.org \
--cc=weixugc@google.com \
--cc=youngjun.park@lge.com \
--cc=yuanchu@google.com \
--cc=yuzhao@google.com \
--cc=ziy@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox