+ mm-gup-dont-allow-foll_longterm-pinning-of-fs-dax-pages.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

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@nvidia.com>
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@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Alison Schofield <alison.schofield@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Asahi Lina <lina@asahilina.net>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@nvidia.com 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