From: Matthew Wilcox <willy@infradead.org>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-doc@vger.kernel.org, cgroups@vger.kernel.org,
linux-sh@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Peter Xu <peterx@redhat.com>, Ryan Roberts <ryan.roberts@arm.com>,
Yin Fengwei <fengwei.yin@intel.com>,
Yang Shi <shy828301@gmail.com>, Zi Yan <ziy@nvidia.com>,
Jonathan Corbet <corbet@lwn.net>, Hugh Dickins <hughd@google.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
Chris Zankel <chris@zankel.net>,
Max Filippov <jcmvbkbc@gmail.com>,
Muchun Song <muchun.song@linux.dev>,
Miaohe Lin <linmiaohe@huawei.com>,
Naoya Horiguchi <naoya.horiguchi@nec.com>,
Richard Chang <richardycc@google.com>
Subject: Re: [PATCH v1 01/18] mm: allow for detecting underflows with page_mapcount() again
Date: Tue, 9 Apr 2024 22:42:29 +0100 [thread overview]
Message-ID: <ZhW2RQtKDvUrbyWA@casper.infradead.org> (raw)
In-Reply-To: <20240409192301.907377-2-david@redhat.com>
On Tue, Apr 09, 2024 at 09:22:44PM +0200, David Hildenbrand wrote:
> Commit 53277bcf126d ("mm: support page_mapcount() on page_has_type()
> pages") made it impossible to detect mapcount underflows by treating
> any negative raw mapcount value as a mapcount of 0.
Yes, but I don't think this is the right place to check for underflow.
We should be checking for that on modification, not on read. I think
it's more important for page_mapcount() to be fast than a debugging aid.
next prev parent reply other threads:[~2024-04-09 21:42 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-09 19:22 [PATCH v1 00/18] mm: mapcount for large folios + page_mapcount() cleanups David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 01/18] mm: allow for detecting underflows with page_mapcount() again David Hildenbrand
2024-04-09 20:06 ` Zi Yan
2024-04-09 21:42 ` Matthew Wilcox [this message]
2024-04-10 8:10 ` David Hildenbrand
2024-04-24 9:38 ` David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 02/18] mm/rmap: always inline anon/file rmap duplication of a single PTE David Hildenbrand
2024-04-19 2:25 ` Yin, Fengwei
2024-04-19 9:14 ` David Hildenbrand
2024-04-19 14:01 ` Yin, Fengwei
2024-04-09 19:22 ` [PATCH v1 03/18] mm/rmap: add fast-path for small folios when adding/removing/duplicating David Hildenbrand
2024-04-19 14:02 ` Yin, Fengwei
2024-04-09 19:22 ` [PATCH v1 04/18] mm: track mapcount of large folios in single value David Hildenbrand
2024-04-09 20:13 ` Zi Yan
2024-04-10 8:20 ` David Hildenbrand
2024-04-18 14:50 ` Lance Yang
2024-04-18 15:09 ` David Hildenbrand
2024-04-19 0:31 ` Lance Yang
2024-04-19 14:02 ` Yin, Fengwei
2024-04-09 19:22 ` [PATCH v1 05/18] mm: improve folio_likely_mapped_shared() using the mapcount of large folios David Hildenbrand
2024-04-16 10:40 ` Lance Yang
2024-04-16 10:47 ` David Hildenbrand
2024-04-16 10:52 ` Lance Yang
2024-04-16 10:53 ` David Hildenbrand
2024-04-19 2:29 ` Yin, Fengwei
2024-04-19 9:19 ` David Hildenbrand
2024-04-19 13:47 ` Yin, Fengwei
2024-04-19 13:48 ` David Hildenbrand
2024-04-19 14:03 ` Yin, Fengwei
2024-04-09 19:22 ` [PATCH v1 06/18] mm: make folio_mapcount() return 0 for small typed folios David Hildenbrand
2024-04-24 9:40 ` David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 07/18] mm/memory: use folio_mapcount() in zap_present_folio_ptes() David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 08/18] mm/huge_memory: use folio_mapcount() in zap_huge_pmd() sanity check David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 09/18] mm/memory-failure: use folio_mapcount() in hwpoison_user_mappings() David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 10/18] mm/page_alloc: use folio_mapped() in __alloc_contig_migrate_range() David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 11/18] mm/migrate: use folio_likely_mapped_shared() in add_page_for_migration() David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 12/18] sh/mm/cache: use folio_mapped() in copy_from_user_page() David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 13/18] mm/filemap: use folio_mapcount() in filemap_unaccount_folio() David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 14/18] mm/migrate_device: use folio_mapcount() in migrate_vma_check_page() David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 15/18] trace/events/page_ref: trace the raw page mapcount value David Hildenbrand
2024-04-09 19:22 ` [PATCH v1 16/18] xtensa/mm: convert check_tlb_entry() to sanity check folios David Hildenbrand
2024-04-09 19:23 ` [PATCH v1 17/18] mm/debug: print only page mapcount (excluding folio entire mapcount) in __dump_folio() David Hildenbrand
2024-04-09 19:23 ` [PATCH v1 18/18] Documentation/admin-guide/cgroup-v1/memory.rst: don't reference page_mapcount() David Hildenbrand
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=ZhW2RQtKDvUrbyWA@casper.infradead.org \
--to=willy@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=chris@zankel.net \
--cc=corbet@lwn.net \
--cc=dalias@libc.org \
--cc=david@redhat.com \
--cc=fengwei.yin@intel.com \
--cc=glaubitz@physik.fu-berlin.de \
--cc=hughd@google.com \
--cc=jcmvbkbc@gmail.com \
--cc=linmiaohe@huawei.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-sh@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=muchun.song@linux.dev \
--cc=naoya.horiguchi@nec.com \
--cc=peterx@redhat.com \
--cc=richardycc@google.com \
--cc=ryan.roberts@arm.com \
--cc=shy828301@gmail.com \
--cc=ysato@users.sourceforge.jp \
--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;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).