The patch titled
Subject: mm/meremap_pages: delete put_devmap_managed_page_refs()
has been added to the -mm mm-unstable branch. Its filename is
mm-meremap_pages-delete-put_devmap_managed_page_refs.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-meremap_pages-delete-put_devmap_managed_page_refs.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: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: mm/meremap_pages: delete put_devmap_managed_page_refs()
Date: Fri, 14 Oct 2022 16:59:17 -0700
Now that fsdax DMA-idle detection no longer depends on catching
transitions of page->_refcount to 1, and all users of pgmap pages get
access to them via pgmap_request_folios(), remove
put_devmap_managed_page_refs() and associated infrastructure. This
includes the pgmap references taken at the beginning of time for each page
because those @pgmap references are now arbitrated via
pgmap_request_folios().
Link: https://lkml.kernel.org/r/166579195789.2236710.7946318795534242314.stgit@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: "Christian König" <christian.koenig@xxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: Karol Herbst <kherbst@xxxxxxxxxx>
Cc: kernel test robot <lkp@xxxxxxxxx>
Cc: Lyude Paul <lyude@xxxxxxxxxx>
Cc: "Pan, Xinhui" <Xinhui.Pan@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 30 ------------------------------
mm/gup.c | 6 ++----
mm/memremap.c | 38 --------------------------------------
mm/swap.c | 2 --
4 files changed, 2 insertions(+), 74 deletions(-)
--- a/include/linux/mm.h~mm-meremap_pages-delete-put_devmap_managed_page_refs
+++ a/include/linux/mm.h
@@ -1082,30 +1082,6 @@ vm_fault_t finish_mkwrite_fault(struct v
* back into memory.
*/
-#if defined(CONFIG_ZONE_DEVICE) && defined(CONFIG_FS_DAX)
-DECLARE_STATIC_KEY_FALSE(devmap_managed_key);
-
-bool __put_devmap_managed_page_refs(struct page *page, int refs);
-static inline bool put_devmap_managed_page_refs(struct page *page, int refs)
-{
- if (!static_branch_unlikely(&devmap_managed_key))
- return false;
- if (!is_zone_device_page(page))
- return false;
- return __put_devmap_managed_page_refs(page, refs);
-}
-#else /* CONFIG_ZONE_DEVICE && CONFIG_FS_DAX */
-static inline bool put_devmap_managed_page_refs(struct page *page, int refs)
-{
- return false;
-}
-#endif /* CONFIG_ZONE_DEVICE && CONFIG_FS_DAX */
-
-static inline bool put_devmap_managed_page(struct page *page)
-{
- return put_devmap_managed_page_refs(page, 1);
-}
-
/* 127: arbitrary random number, small enough to assemble well */
#define folio_ref_zero_or_close_to_overflow(folio) \
((unsigned int) folio_ref_count(folio) + 127u <= 127u)
@@ -1202,12 +1178,6 @@ static inline void put_page(struct page
{
struct folio *folio = page_folio(page);
- /*
- * For some devmap managed pages we need to catch refcount transition
- * from 2 to 1:
- */
- if (put_devmap_managed_page(&folio->page))
- return;
folio_put(folio);
}
--- a/mm/gup.c~mm-meremap_pages-delete-put_devmap_managed_page_refs
+++ a/mm/gup.c
@@ -87,8 +87,7 @@ retry:
* belongs to this folio.
*/
if (unlikely(page_folio(page) != folio)) {
- if (!put_devmap_managed_page_refs(&folio->page, refs))
- folio_put_refs(folio, refs);
+ folio_put_refs(folio, refs);
goto retry;
}
@@ -184,8 +183,7 @@ static void gup_put_folio(struct folio *
refs *= GUP_PIN_COUNTING_BIAS;
}
- if (!put_devmap_managed_page_refs(&folio->page, refs))
- folio_put_refs(folio, refs);
+ folio_put_refs(folio, refs);
}
/**
--- a/mm/memremap.c~mm-meremap_pages-delete-put_devmap_managed_page_refs
+++ a/mm/memremap.c
@@ -94,19 +94,6 @@ bool pgmap_pfn_valid(struct dev_pagemap
return false;
}
-static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id)
-{
- const struct range *range = &pgmap->ranges[range_id];
-
- return (range->start + range_len(range)) >> PAGE_SHIFT;
-}
-
-static unsigned long pfn_len(struct dev_pagemap *pgmap, unsigned long range_id)
-{
- return (pfn_end(pgmap, range_id) -
- pfn_first(pgmap, range_id)) >> pgmap->vmemmap_shift;
-}
-
static void pageunmap_range(struct dev_pagemap *pgmap, int range_id)
{
struct range *range = &pgmap->ranges[range_id];
@@ -138,10 +125,6 @@ void memunmap_pages(struct dev_pagemap *
int i;
percpu_ref_kill(&pgmap->ref);
- if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
- pgmap->type != MEMORY_DEVICE_COHERENT)
- for (i = 0; i < pgmap->nr_range; i++)
- percpu_ref_put_many(&pgmap->ref, pfn_len(pgmap, i));
wait_for_completion(&pgmap->done);
@@ -267,9 +250,6 @@ static int pagemap_range(struct dev_page
memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
PHYS_PFN(range->start),
PHYS_PFN(range_len(range)), pgmap);
- if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
- pgmap->type != MEMORY_DEVICE_COHERENT)
- percpu_ref_get_many(&pgmap->ref, pfn_len(pgmap, range_id));
return 0;
err_add_memory:
@@ -584,21 +564,3 @@ void pgmap_release_folios(struct folio *
for (iter = folio, i = 0; i < nr_folios; iter = folio_next(folio), i++)
folio_put(iter);
}
-
-#ifdef CONFIG_FS_DAX
-bool __put_devmap_managed_page_refs(struct page *page, int refs)
-{
- if (page->pgmap->type != MEMORY_DEVICE_FS_DAX)
- return false;
-
- /*
- * fsdax page refcounts are 1-based, rather than 0-based: if
- * refcount is 1, then the page is free and the refcount is
- * stable because nobody holds a reference on the page.
- */
- if (page_ref_sub_return(page, refs) == 1)
- wake_up_var(page);
- return true;
-}
-EXPORT_SYMBOL(__put_devmap_managed_page_refs);
-#endif /* CONFIG_FS_DAX */
--- a/mm/swap.c~mm-meremap_pages-delete-put_devmap_managed_page_refs
+++ a/mm/swap.c
@@ -1015,8 +1015,6 @@ void release_pages(struct page **pages,
unlock_page_lruvec_irqrestore(lruvec, flags);
lruvec = NULL;
}
- if (put_devmap_managed_page(&folio->page))
- continue;
if (folio_put_testzero(folio))
free_zone_device_page(&folio->page);
continue;
_
Patches currently in -mm which might be from dan.j.williams@xxxxxxxxx are
fsdax-wait-on-page-not-page-_refcount.patch
fsdax-use-dax_page_idle-to-document-dax-busy-page-checking.patch
fsdax-include-unmapped-inodes-for-page-idle-detection.patch
fsdax-introduce-dax_zap_mappings.patch
fsdax-wait-for-pinned-pages-during-truncate_inode_pages_final.patch
fsdax-validate-dax-layouts-broken-before-truncate.patch
fsdax-hold-dax-lock-over-mapping-insertion.patch
fsdax-update-dax_insert_entry-calling-convention-to-return-an-error.patch
fsdax-rework-for_each_mapped_pfn-to-dax_for_each_folio.patch
fsdax-introduce-pgmap_request_folios.patch
fsdax-rework-dax_insert_entry-calling-convention.patch
fsdax-cleanup-dax_associate_entry.patch
devdax-minor-warning-fixups.patch
devdax-fix-sparse-lock-imbalance-warning.patch
libnvdimm-pmem-support-pmem-block-devices-without-dax.patch
devdax-move-address_space-helpers-to-the-dax-core.patch
devdax-sparse-fixes-for-xarray-locking.patch
devdax-sparse-fixes-for-vmfault_t-dax-entry-conversions.patch
devdax-sparse-fixes-for-vm_fault_t-in-tracepoints.patch
devdax-add-pud-support-to-the-dax-mapping-infrastructure.patch
devdax-use-dax_insert_entry-dax_delete_mapping_entry.patch
mm-memremap_pages-replace-zone_device_page_init-with-pgmap_request_folios.patch
mm-memremap_pages-initialize-all-zone_device-pages-to-start-at-refcount-0.patch
mm-meremap_pages-delete-put_devmap_managed_page_refs.patch
mm-gup-drop-dax-pgmap-accounting.patch
