The patch titled
Subject: mm/gup: introduce unpin_folio/unpin_folios helpers
has been added to the -mm mm-unstable branch. Its filename is
mm-gup-introduce-unpin_folio-unpin_folios-helpers.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-gup-introduce-unpin_folio-unpin_folios-helpers.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: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
Subject: mm/gup: introduce unpin_folio/unpin_folios helpers
Date: Sun, 23 Jun 2024 23:36:09 -0700
Patch series "mm/gup: Introduce memfd_pin_folios() for pinning memfd
folios", v16.
Currently, some drivers (e.g, Udmabuf) that want to longterm-pin the
pages/folios associated with a memfd, do so by simply taking a reference
on them. This is not desirable because the pages/folios may reside in
Movable zone or CMA block.
Therefore, having drivers use memfd_pin_folios() API ensures that the
folios are appropriately pinned via FOLL_PIN for longterm DMA.
This patchset also introduces a few helpers and converts the Udmabuf
driver to use folios and memfd_pin_folios() API to longterm-pin the folios
for DMA. Two new Udmabuf selftests are also included to test the driver
and the new API.
This patch (of 9):
These helpers are the folio versions of unpin_user_page/unpin_user_pages.
They are currently only useful for unpinning folios pinned by
memfd_pin_folios() or other associated routines. However, they could find
new uses in the future, when more and more folio-only helpers are added to
GUP.
We should probably sanity check the folio as part of unpin similar to how
it is done in unpin_user_page/unpin_user_pages but we cannot cleanly do
that at the moment without also checking the subpage. Therefore, sanity
checking needs to be added to these routines once we have a way to
determine if any given folio is anon-exclusive (via a per folio
AnonExclusive flag).
Link: https://lkml.kernel.org/r/20240624063952.1572359-1-vivek.kasireddy@xxxxxxxxx
Link: https://lkml.kernel.org/r/20240624063952.1572359-2-vivek.kasireddy@xxxxxxxxx
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Dave Airlie <airlied@xxxxxxxxxx>
Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Dongwon Kim <dongwon.kim@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Junxiao Chang <junxiao.chang@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 2 +
mm/gup.c | 47 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 49 insertions(+)
--- a/include/linux/mm.h~mm-gup-introduce-unpin_folio-unpin_folios-helpers
+++ a/include/linux/mm.h
@@ -1584,11 +1584,13 @@ static inline void put_page(struct page
#define GUP_PIN_COUNTING_BIAS (1U << 10)
void unpin_user_page(struct page *page);
+void unpin_folio(struct folio *folio);
void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages,
bool make_dirty);
void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages,
bool make_dirty);
void unpin_user_pages(struct page **pages, unsigned long npages);
+void unpin_folios(struct folio **folios, unsigned long nfolios);
static inline bool is_cow_mapping(vm_flags_t flags)
{
--- a/mm/gup.c~mm-gup-introduce-unpin_folio-unpin_folios-helpers
+++ a/mm/gup.c
@@ -277,6 +277,19 @@ void unpin_user_page(struct page *page)
EXPORT_SYMBOL(unpin_user_page);
/**
+ * unpin_folio() - release a dma-pinned folio
+ * @folio: pointer to folio to be released
+ *
+ * Folios that were pinned via memfd_pin_folios() or other similar routines
+ * must be released either using unpin_folio() or unpin_folios().
+ */
+void unpin_folio(struct folio *folio)
+{
+ gup_put_folio(folio, 1, FOLL_PIN);
+}
+EXPORT_SYMBOL_GPL(unpin_folio);
+
+/**
* folio_add_pin - Try to get an additional pin on a pinned folio
* @folio: The folio to be pinned
*
@@ -488,6 +501,40 @@ void unpin_user_pages(struct page **page
}
EXPORT_SYMBOL(unpin_user_pages);
+/**
+ * unpin_folios() - release an array of gup-pinned folios.
+ * @folios: array of folios to be marked dirty and released.
+ * @nfolios: number of folios in the @folios array.
+ *
+ * For each folio in the @folios array, release the folio using gup_put_folio.
+ *
+ * Please see the unpin_folio() documentation for details.
+ */
+void unpin_folios(struct folio **folios, unsigned long nfolios)
+{
+ unsigned long i = 0, j;
+
+ /*
+ * If this WARN_ON() fires, then the system *might* be leaking folios
+ * (by leaving them pinned), but probably not. More likely, gup/pup
+ * returned a hard -ERRNO error to the caller, who erroneously passed
+ * it here.
+ */
+ if (WARN_ON(IS_ERR_VALUE(nfolios)))
+ return;
+
+ while (i < nfolios) {
+ for (j = i + 1; j < nfolios; j++)
+ if (folios[i] != folios[j])
+ break;
+
+ if (folios[i])
+ gup_put_folio(folios[i], j - i, FOLL_PIN);
+ i = j;
+ }
+}
+EXPORT_SYMBOL_GPL(unpin_folios);
+
/*
* Set the MMF_HAS_PINNED if not set yet; after set it'll be there for the mm's
* lifecycle. Avoid setting the bit unless necessary, or it might cause write
_
Patches currently in -mm which might be from vivek.kasireddy@xxxxxxxxx are
mm-gup-introduce-unpin_folio-unpin_folios-helpers.patch
mm-gup-introduce-check_and_migrate_movable_folios.patch
mm-gup-introduce-memfd_pin_folios-for-pinning-memfd-folios.patch
udmabuf-use-vmf_insert_pfn-and-vm_pfnmap-for-handling-mmap.patch
udmabuf-add-back-support-for-mapping-hugetlb-pages.patch
udmabuf-convert-udmabuf-driver-to-use-folios.patch
udmabuf-pin-the-pages-using-memfd_pin_folios-api.patch
selftests-udmabuf-add-tests-to-verify-data-after-page-migration.patch
