From: Jason Gunthorpe <jgg@nvidia.com>
To: Zi Yan <ziy@nvidia.com>
Cc: Balbir Singh <balbirs@nvidia.com>,
David Hildenbrand <david@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Alistair Popple <apopple@nvidia.com>,
Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>, Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Jens Axboe <axboe@kernel.dk>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Nico Pache <npache@redhat.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Oscar Salvador <osalvador@suse.de>,
Brendan Jackman <jackmanb@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
io-uring@vger.kernel.org
Subject: Re: [RFC PATCH 0/5] Separate compound page from folio
Date: Wed, 4 Feb 2026 14:49:11 -0400 [thread overview]
Message-ID: <20260204184911.GI3931454@nvidia.com> (raw)
In-Reply-To: <33B161E0-5468-4A31-A5BC-B4F1FCE72CEC@nvidia.com>
On Wed, Feb 04, 2026 at 01:29:45PM -0500, Zi Yan wrote:
> > For in-tree users, I am converting them all in this series.
>
> Considering a recent report[1], where drivers/scsi/sg.c allocates compound
> pages with __GFP_COMP and maps them into userspace via sg_vma_fault(),
> I guess almost all __GFP_COMP users are really using folios instead of
> compound pages.
This would be my guess, and it seems like a good cleanup to make them
actually create fully proper folios if they are being mmaped.
I suspect the only places not using "folios" are frozen page users (or
places yet to be converted to frozen pages)
Which is back to my previous remarks that having a good definition for
what struct page memory is allowed to be used by a frozen page user
would be helpful. If the mm can retain some of the tail page memory
for itself you don't need to make several of the changes here.
Jason
prev parent reply other threads:[~2026-02-04 18:49 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-30 3:48 [RFC PATCH 0/5] Separate compound page from folio Zi Yan
2026-01-30 3:48 ` [RFC PATCH 1/5] io_uring: allocate folio in io_mem_alloc_compound() and function rename Zi Yan
2026-01-31 15:30 ` Lance Yang
2026-02-01 2:04 ` Zi Yan
2026-01-30 3:48 ` [RFC PATCH 2/5] mm/huge_memory: use page_rmappable_folio() to convert after-split folios Zi Yan
2026-01-30 3:48 ` [RFC PATCH 3/5] mm/hugetlb: set large_rmappable on hugetlb and avoid deferred_list handling Zi Yan
2026-02-02 3:59 ` Baolin Wang
2026-02-02 17:11 ` Zi Yan
2026-01-30 3:48 ` [RFC PATCH 4/5] mm: only use struct page in compound_nr() and compound_order() Zi Yan
2026-01-30 3:48 ` [RFC PATCH 5/5] mm: code separation for compound page and folio Zi Yan
2026-01-30 8:15 ` [syzbot ci] Re: Separate compound page from folio syzbot ci
2026-01-30 16:39 ` [syzbot ci] " Zi Yan
2026-01-30 16:41 ` syzbot ci
2026-02-03 4:30 ` [RFC PATCH 0/5] " Balbir Singh
2026-02-04 16:21 ` Zi Yan
2026-02-04 18:29 ` Zi Yan
2026-02-04 18:49 ` Jason Gunthorpe [this message]
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