From: Andrew Morton <akpm@linux-foundation.org>
To: Alistair Popple <apopple@nvidia.com>
Cc: dan.j.williams@intel.com, linux-mm@kvack.org, lina@asahilina.net,
zhang.lyra@gmail.com, gerald.schaefer@linux.ibm.com,
vishal.l.verma@intel.com, dave.jiang@intel.com,
logang@deltatee.com, bhelgaas@google.com, jack@suse.cz,
jgg@ziepe.ca, catalin.marinas@arm.com, will@kernel.org,
mpe@ellerman.id.au, npiggin@gmail.com,
dave.hansen@linux.intel.com, ira.weiny@intel.com,
willy@infradead.org, djwong@kernel.org, tytso@mit.edu,
linmiaohe@huawei.com, david@redhat.com, peterx@redhat.com,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org, nvdimm@lists.linux.dev,
linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
jhubbard@nvidia.com, hch@lst.de, david@fromorbit.com
Subject: Re: [PATCH v5 00/25] fs/dax: Fix ZONE_DEVICE page reference counts
Date: Tue, 7 Jan 2025 22:26:43 -0800 [thread overview]
Message-ID: <20250107222643.80d5509219d6b66c15b1b8af@linux-foundation.org> (raw)
In-Reply-To: <cover.425da7c4e76c2749d0ad1734f972b06114e02d52.1736221254.git-series.apopple@nvidia.com>
On Tue, 7 Jan 2025 14:42:16 +1100 Alistair Popple <apopple@nvidia.com> wrote:
> Device and FS DAX pages have always maintained their own page
> reference counts without following the normal rules for page reference
> counting. In particular pages are considered free when the refcount
> hits one rather than zero and refcounts are not added when mapping the
> page.
>
> Tracking this requires special PTE bits (PTE_DEVMAP) and a secondary
> mechanism for allowing GUP to hold references on the page (see
> get_dev_pagemap). However there doesn't seem to be any reason why FS
> DAX pages need their own reference counting scheme.
>
> By treating the refcounts on these pages the same way as normal pages
> we can remove a lot of special checks. In particular pXd_trans_huge()
> becomes the same as pXd_leaf(), although I haven't made that change
> here. It also frees up a valuable SW define PTE bit on architectures
> that have devmap PTE bits defined.
>
> It also almost certainly allows further clean-up of the devmap managed
> functions, but I have left that as a future improvment. It also
> enables support for compound ZONE_DEVICE pages which is one of my
> primary motivators for doing this work.
>
https://lkml.kernel.org/r/wysuus23bqmjtwkfu3zutqtmkse3ki3erf45x32yezlrl24qto@xlqt7qducyld
made me expect merge/build/runtime issues, however this series merges
and builds OK on mm-unstable. Did something change? What's the story
here?
Oh well, it built so I'll ship it!
next prev parent reply other threads:[~2025-01-08 6:26 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-07 3:42 Alistair Popple
2025-01-07 3:42 ` [PATCH v5 01/25] fuse: Fix dax truncate/punch_hole fault path Alistair Popple
2025-01-08 22:30 ` Dan Williams
2025-01-09 4:38 ` Alistair Popple
2025-01-07 3:42 ` [PATCH v5 02/25] fs/dax: Return unmapped busy pages from dax_layout_busy_page_range() Alistair Popple
2025-01-08 22:30 ` Dan Williams
2025-01-07 3:42 ` [PATCH v5 03/25] fs/dax: Don't skip locked entries when scanning entries Alistair Popple
2025-01-08 22:50 ` Dan Williams
2025-01-09 5:21 ` Alistair Popple
2025-01-07 3:42 ` [PATCH v5 04/25] fs/dax: Refactor wait for dax idle page Alistair Popple
2025-01-07 3:42 ` [PATCH v5 05/25] fs/dax: Create a common implementation to break DAX layouts Alistair Popple
2025-01-09 0:14 ` Dan Williams
2025-01-09 6:15 ` Alistair Popple
2025-01-10 6:56 ` Dan Williams
2025-01-07 3:42 ` [PATCH v5 06/25] fs/dax: Always remove DAX page-cache entries when breaking layouts Alistair Popple
2025-01-07 3:42 ` [PATCH v5 07/25] fs/dax: Ensure all pages are idle prior to filesystem unmount Alistair Popple
2025-01-07 3:42 ` [PATCH v5 08/25] fs/dax: Remove PAGE_MAPPING_DAX_SHARED mapping flag Alistair Popple
2025-01-07 3:42 ` [PATCH v5 09/25] mm/gup: Remove redundant check for PCI P2PDMA page Alistair Popple
2025-01-07 3:42 ` [PATCH v5 10/25] mm/mm_init: Move p2pdma page refcount initialisation to p2pdma Alistair Popple
2025-01-07 3:42 ` [PATCH v5 11/25] mm: Allow compound zone device pages Alistair Popple
2025-01-07 3:42 ` [PATCH v5 12/25] mm/memory: Enhance insert_page_into_pte_locked() to create writable mappings Alistair Popple
2025-01-07 3:42 ` [PATCH v5 13/25] mm/memory: Add vmf_insert_page_mkwrite() Alistair Popple
2025-01-07 3:42 ` [PATCH v5 14/25] rmap: Add support for PUD sized mappings to rmap Alistair Popple
2025-01-07 11:36 ` David Hildenbrand
2025-01-07 3:42 ` [PATCH v5 15/25] huge_memory: Add vmf_insert_folio_pud() Alistair Popple
2025-01-08 3:54 ` kernel test robot
2025-01-07 3:42 ` [PATCH v5 16/25] huge_memory: Add vmf_insert_folio_pmd() Alistair Popple
2025-01-07 3:42 ` [PATCH v5 17/25] memremap: Add is_devdax_page() and is_fsdax_page() helpers Alistair Popple
2025-01-07 3:42 ` [PATCH v5 18/25] mm/gup: Don't allow FOLL_LONGTERM pinning of FS DAX pages Alistair Popple
2025-01-07 3:42 ` [PATCH v5 19/25] proc/task_mmu: Mark devdax and fsdax pages as always unpinned Alistair Popple
2025-01-07 3:42 ` [PATCH v5 20/25] mm/mlock: Skip ZONE_DEVICE PMDs during mlock Alistair Popple
2025-01-07 3:42 ` [PATCH v5 21/25] fs/dax: Properly refcount fs dax pages Alistair Popple
2025-01-07 3:42 ` [PATCH v5 22/25] device/dax: Properly refcount device dax pages when mapping Alistair Popple
2025-01-07 3:42 ` [PATCH v5 23/25] mm: Remove pXX_devmap callers Alistair Popple
2025-01-07 3:42 ` [PATCH v5 24/25] mm: Remove devmap related functions and page table bits Alistair Popple
2025-01-07 3:42 ` [PATCH v5 25/25] Revert "riscv: mm: Add support for ZONE_DEVICE" Alistair Popple
2025-01-08 6:26 ` Andrew Morton [this message]
2025-01-08 21:51 ` [PATCH v5 00/25] fs/dax: Fix ZONE_DEVICE page reference counts Dan Williams
2025-01-09 1:34 ` Alison Schofield
2025-01-10 6:03 ` Alistair Popple
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