From: "Michael S. Tsirkin" <mst@redhat.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
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Nhat Pham <nphamcs@gmail.com>, Baoquan He <bhe@redhat.com>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH RFC v3 01/19] mm: thread user_addr through page allocator for cache-friendly zeroing
Date: Sun, 26 Apr 2026 16:54:35 -0400 [thread overview]
Message-ID: <20260426165330-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <aeu5P1bZW3yEH54t@casper.infradead.org>
On Fri, Apr 24, 2026 at 07:41:03PM +0100, Matthew Wilcox wrote:
> On Tue, Apr 21, 2026 at 06:01:10PM -0400, Michael S. Tsirkin wrote:
> > Thread a user virtual address from vma_alloc_folio() down through
> > the page allocator to post_alloc_hook(). This is plumbing preparation
> > for a subsequent patch that will use user_addr to call folio_zero_user()
> > for cache-friendly zeroing of user pages.
> >
> > The user_addr is stored in struct alloc_context and flows through:
> > vma_alloc_folio -> folio_alloc_mpol -> __alloc_pages_mpol ->
> > __alloc_frozen_pages -> get_page_from_freelist -> prep_new_page ->
> > post_alloc_hook
>
> I don't like this. I think we should instead lift the zeroing from
> post_alloc_hook() to the callers of __alloc_frozen_pages().
can you and david agree somehow? I don't like being caught betweem
maintainers like this.
> I don't understand why you want to remove the double-zeroing of memory
> when the user has asked for zero_on_alloc. They asked for stupid things,
> let them bear the cost.
it's just a side effect. I did not even test what effect it has.
what I care about is the overhead with
reporting.
next prev parent reply other threads:[~2026-04-26 20:54 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-21 22:01 [PATCH RFC v3 00/19] mm/virtio: skip redundant zeroing of host-zeroed reported pages Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 01/19] mm: thread user_addr through page allocator for cache-friendly zeroing Michael S. Tsirkin
2026-04-22 19:47 ` Gregory Price
2026-04-22 20:32 ` Michael S. Tsirkin
2026-04-22 21:20 ` Michael S. Tsirkin
2026-04-23 4:31 ` Gregory Price
2026-04-23 9:46 ` David Hildenbrand (Arm)
2026-04-23 11:57 ` Michael S. Tsirkin
2026-04-23 13:42 ` Gregory Price
2026-04-23 14:13 ` David Hildenbrand (Arm)
2026-04-23 14:46 ` Michael S. Tsirkin
2026-04-23 15:54 ` David Hildenbrand (Arm)
2026-04-23 16:13 ` Michael S. Tsirkin
2026-04-24 18:33 ` David Hildenbrand (Arm)
2026-04-24 18:36 ` Michael S. Tsirkin
2026-04-24 18:41 ` David Hildenbrand (Arm)
2026-04-23 14:57 ` Gregory Price
2026-04-24 7:28 ` David Hildenbrand (Arm)
2026-04-24 12:30 ` Gregory Price
2026-04-24 12:33 ` Michael S. Tsirkin
2026-04-24 18:41 ` Matthew Wilcox
2026-04-24 18:51 ` David Hildenbrand (Arm)
2026-04-26 20:54 ` Michael S. Tsirkin [this message]
2026-04-21 22:01 ` [PATCH RFC v3 02/19] mm: add folio_zero_user stub for configs without THP/HUGETLBFS Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 03/19] mm: page_alloc: move prep_compound_page before post_alloc_hook Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 04/19] mm: use folio_zero_user for user pages in post_alloc_hook Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 05/19] mm: use __GFP_ZERO in vma_alloc_zeroed_movable_folio Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 06/19] mm: use __GFP_ZERO in alloc_anon_folio Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 07/19] mm: use __GFP_ZERO in vma_alloc_anon_folio_pmd Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 08/19] mm: hugetlb: use __GFP_ZERO and skip zeroing for zeroed pages Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 09/19] mm: memfd: skip zeroing for zeroed hugetlb pool pages Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 10/19] mm: remove arch vma_alloc_zeroed_movable_folio overrides Michael S. Tsirkin
2026-04-22 6:54 ` Geert Uytterhoeven
2026-04-22 21:29 ` Greg Ungerer
2026-04-24 7:16 ` Magnus Lindholm
2026-04-21 22:01 ` [PATCH RFC v3 11/19] mm: page_alloc: propagate PageReported flag across buddy splits Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 12/19] mm: page_reporting: skip redundant zeroing of host-zeroed reported pages Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 13/19] virtio_balloon: a hack to enable host-zeroed page optimization Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 14/19] mm: page_reporting: add flush parameter with page budget Michael S. Tsirkin
2026-04-21 22:01 ` [PATCH RFC v3 15/19] mm: add free_frozen_pages_zeroed Michael S. Tsirkin
2026-04-21 22:02 ` [PATCH RFC v3 16/19] mm: add put_page_zeroed and folio_put_zeroed Michael S. Tsirkin
2026-04-21 22:02 ` [PATCH RFC v3 17/19] mm: page_alloc: clear PG_zeroed on buddy merge if not both zero Michael S. Tsirkin
2026-04-21 22:02 ` [PATCH RFC v3 18/19] mm: page_alloc: preserve PG_zeroed in page_del_and_expand Michael S. Tsirkin
2026-04-21 22:02 ` [PATCH RFC v3 19/19] virtio_balloon: mark deflated pages as zeroed Michael S. Tsirkin
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