[PATCH v9 17/20] mm/gup: Don't allow FOLL_LONGTERM pinning of FS DAX pages
From: Alistair Popple <apopple@nvidia.com>
Date: 2025-02-28 03:32:46
Also in:
linux-arm-kernel, linux-cxl, linux-doc, linux-fsdevel, linux-mm, linux-xfs, linuxppc-dev, lkml, loongarch, nvdimm
Subsystem:
memory hot(un)plug, memory management - core, the rest · Maintainers:
David Hildenbrand, Oscar Salvador, Andrew Morton, Linus Torvalds
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. Signed-off-by: Alistair Popple <apopple@nvidia.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Dan Williams <redacted> Acked-by: David Hildenbrand <redacted> --- include/linux/memremap.h | 11 +++++++++++ include/linux/mm.h | 7 +++++++ 2 files changed, 18 insertions(+)
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 0256a42..4aa1519 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h@@ -187,6 +187,17 @@ static inline bool folio_is_device_coherent(const struct folio *folio) 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);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d1f260d..066aebd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -2109,6 +2109,13 @@ static inline bool folio_is_longterm_pinnable(struct folio *folio) 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);
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