The patch titled
Subject: mm: simplify freeing of devmap managed pages
has been added to the -mm tree. Its filename is
mm-simplify-freeing-of-devmap-managed-pages.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-simplify-freeing-of-devmap-managed-pages.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-simplify-freeing-of-devmap-managed-pages.patch
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------------------------------------------------------
From: Christoph Hellwig <hch@xxxxxx>
Subject: mm: simplify freeing of devmap managed pages
Make put_devmap_managed_page return if it took charge of the page
or not and remove the separate page_is_devmap_managed helper.
Link: https://lkml.kernel.org/r/20220210072828.2930359-6-hch@xxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Tested-by: "Sierra Guiza, Alejandro (Alex)" <alex.sierra@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: Christian Knig <christian.koenig@xxxxxxx>
Cc: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Cc: Karol Herbst <kherbst@xxxxxxxxxx>
Cc: Lyude Paul <lyude@xxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: "Pan, Xinhui" <Xinhui.Pan@xxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/include/linux/mm.h~mm-simplify-freeing-of-devmap-managed-pages
+++ a/include/linux/mm.h
@@ -1089,33 +1089,24 @@ static inline bool is_zone_movable_page(
#ifdef CONFIG_DEV_PAGEMAP_OPS
DECLARE_STATIC_KEY_FALSE(devmap_managed_key);
-static inline bool page_is_devmap_managed(struct page *page)
+bool __put_devmap_managed_page(struct page *page);
+static inline bool put_devmap_managed_page(struct page *page)
{
if (!static_branch_unlikely(&devmap_managed_key))
return false;
if (!is_zone_device_page(page))
return false;
- switch (page->pgmap->type) {
- case MEMORY_DEVICE_PRIVATE:
- case MEMORY_DEVICE_FS_DAX:
- return true;
- default:
- break;
- }
- return false;
+ if (page->pgmap->type != MEMORY_DEVICE_PRIVATE &&
+ page->pgmap->type != MEMORY_DEVICE_FS_DAX)
+ return false;
+ return __put_devmap_managed_page(page);
}
-void put_devmap_managed_page(struct page *page);
-
#else /* CONFIG_DEV_PAGEMAP_OPS */
-static inline bool page_is_devmap_managed(struct page *page)
+static inline bool put_devmap_managed_page(struct page *page)
{
return false;
}
-
-static inline void put_devmap_managed_page(struct page *page)
-{
-}
#endif /* CONFIG_DEV_PAGEMAP_OPS */
static inline bool is_device_private_page(const struct page *page)
@@ -1215,16 +1206,11 @@ static inline void put_page(struct page
struct folio *folio = page_folio(page);
/*
- * For devmap managed pages we need to catch refcount transition from
- * 2 to 1, when refcount reach one it means the page is free and we
- * need to inform the device driver through callback. See
- * include/linux/memremap.h and HMM for details.
+ * For some devmap managed pages we need to catch refcount transition
+ * from 2 to 1:
*/
- if (page_is_devmap_managed(&folio->page)) {
- put_devmap_managed_page(&folio->page);
+ if (put_devmap_managed_page(&folio->page))
return;
- }
-
folio_put(folio);
}
--- a/mm/memremap.c~mm-simplify-freeing-of-devmap-managed-pages
+++ a/mm/memremap.c
@@ -523,24 +523,22 @@ void free_devmap_managed_page(struct pag
page->pgmap->ops->page_free(page);
}
-void put_devmap_managed_page(struct page *page)
+bool __put_devmap_managed_page(struct page *page)
{
- int count;
-
- if (WARN_ON_ONCE(!page_is_devmap_managed(page)))
- return;
-
- count = page_ref_dec_return(page);
-
/*
* devmap 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 (count == 1)
+ switch (page_ref_dec_return(page)) {
+ case 1:
free_devmap_managed_page(page);
- else if (!count)
+ break;
+ case 0:
__put_page(page);
+ break;
+ }
+ return true;
}
-EXPORT_SYMBOL(put_devmap_managed_page);
+EXPORT_SYMBOL(__put_devmap_managed_page);
#endif /* CONFIG_DEV_PAGEMAP_OPS */
--- a/mm/swap.c~mm-simplify-freeing-of-devmap-managed-pages
+++ a/mm/swap.c
@@ -930,16 +930,8 @@ void release_pages(struct page **pages,
unlock_page_lruvec_irqrestore(lruvec, flags);
lruvec = NULL;
}
- /*
- * ZONE_DEVICE pages that return 'false' from
- * page_is_devmap_managed() do not require special
- * processing, and instead, expect a call to
- * put_page_testzero().
- */
- if (page_is_devmap_managed(page)) {
- put_devmap_managed_page(page);
+ if (put_devmap_managed_page(page))
continue;
- }
if (put_page_testzero(page))
put_dev_pagemap(page->pgmap);
continue;
_
Patches currently in -mm which might be from hch@xxxxxx are
mm-unexport-page_init_poison.patch
mm-remove-a-pointless-config_zone_device-check-in-memremap_pages.patch
mm-remove-the-__kernel__-guard-from-linux-mmh.patch
mm-remove-pointless-includes-from-linux-hmmh.patch
mm-move-free_devmap_managed_page-to-memremapc.patch
mm-simplify-freeing-of-devmap-managed-pages.patch
mm-dont-include-linux-memremaph-in-linux-mmh.patch
mm-remove-the-extra-zone_device-struct-page-refcount.patch
fsdax-depend-on-zone_device-fs_dax_limited.patch
mm-generalize-the-pgmap-based-page_free-infrastructure.patch
mm-refactor-check_and_migrate_movable_pages.patch
mm-refactor-the-zone_device-handling-in-migrate_vma_insert_page.patch
mm-refactor-the-zone_device-handling-in-migrate_vma_pages.patch
mm-move-the-migrate_vma_-device-migration-code-into-its-own-file.patch
mm-build-migrate_vma_-for-all-configs-with-zone_device-support.patch
mm-add-zone-device-coherent-type-memory-support.patch
mm-add-device-coherent-vma-selection-for-memory-migration.patch
