The patch titled
Subject: mm/gup: don't allow FOLL_LONGTERM pinning of FS DAX pages
has been added to the -mm mm-unstable branch. Its filename is
mm-gup-dont-allow-foll_longterm-pinning-of-fs-dax-pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-gup-dont-allow-foll_longterm-pinning-of-fs-dax-pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Alistair Popple <apopple@xxxxxxxxxx>
Subject: mm/gup: don't allow FOLL_LONGTERM pinning of FS DAX pages
Date: Tue, 18 Feb 2025 14:55:33 +1100
Longterm pinning of FS DAX pages should already be disallowed by various
pXX_devmap checks. However a future change will cause these checks to be
invalid for FS DAX pages so make folio_is_longterm_pinnable() return false
for FS DAX pages.
Link: https://lkml.kernel.org/r/9cc175f877358da2fcf1b2b769030d457c16c5dc.1739850794.git-series.apopple@xxxxxxxxxx
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Tested-by: Alison Schofield <alison.schofield@xxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Asahi Lina <lina@xxxxxxxxxxxxx>
Cc: Balbir Singh <balbirs@xxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Chunyan Zhang <zhang.lyra@xxxxxxxxx>
Cc: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: Ted Ts'o <tytso@xxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: WANG Xuerui <kernel@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memremap.h | 11 +++++++++++
include/linux/mm.h | 7 +++++++
2 files changed, 18 insertions(+)
--- a/include/linux/memremap.h~mm-gup-dont-allow-foll_longterm-pinning-of-fs-dax-pages
+++ a/include/linux/memremap.h
@@ -187,6 +187,17 @@ static inline bool folio_is_device_coher
return is_device_coherent_page(&folio->page);
}
+static inline bool is_fsdax_page(const struct page *page)
+{
+ return is_zone_device_page(page) &&
+ page_pgmap(page)->type == MEMORY_DEVICE_FS_DAX;
+}
+
+static inline bool folio_is_fsdax(const struct folio *folio)
+{
+ return is_fsdax_page(&folio->page);
+}
+
#ifdef CONFIG_ZONE_DEVICE
void zone_device_page_init(struct page *page);
void *memremap_pages(struct dev_pagemap *pgmap, int nid);
--- a/include/linux/mm.h~mm-gup-dont-allow-foll_longterm-pinning-of-fs-dax-pages
+++ a/include/linux/mm.h
@@ -2109,6 +2109,13 @@ static inline bool folio_is_longterm_pin
if (folio_is_device_coherent(folio))
return false;
+ /*
+ * Filesystems can only tolerate transient delays to truncate and
+ * hole-punch operations
+ */
+ if (folio_is_fsdax(folio))
+ return false;
+
/* Otherwise, non-movable zone folios can be pinned. */
return !folio_is_zone_movable(folio);
_
Patches currently in -mm which might be from apopple@xxxxxxxxxx are
fuse-fix-dax-truncate-punch_hole-fault-path.patch
fs-dax-return-unmapped-busy-pages-from-dax_layout_busy_page_range.patch
fs-dax-dont-skip-locked-entries-when-scanning-entries.patch
fs-dax-refactor-wait-for-dax-idle-page.patch
fs-dax-create-a-common-implementation-to-break-dax-layouts.patch
fs-dax-always-remove-dax-page-cache-entries-when-breaking-layouts.patch
fs-dax-ensure-all-pages-are-idle-prior-to-filesystem-unmount.patch
fs-dax-remove-page_mapping_dax_shared-mapping-flag.patch
mm-gup-remove-redundant-check-for-pci-p2pdma-page.patch
mm-mm_init-move-p2pdma-page-refcount-initialisation-to-p2pdma.patch
mm-allow-compound-zone-device-pages.patch
mm-memory-enhance-insert_page_into_pte_locked-to-create-writable-mappings.patch
mm-memory-add-vmf_insert_page_mkwrite.patch
mm-rmap-add-support-for-pud-sized-mappings-to-rmap.patch
mm-huge_memory-add-vmf_insert_folio_pud.patch
mm-huge_memory-add-vmf_insert_folio_pmd.patch
mm-gup-dont-allow-foll_longterm-pinning-of-fs-dax-pages.patch
fs-dax-properly-refcount-fs-dax-pages.patch
device-dax-properly-refcount-device-dax-pages-when-mapping.patch
