From: Christoph Hellwig <hch@lst.de>
Date: Wed, 16 Feb 2022 15:31:35 +1100
Subject: mm: simplify freeing of devmap managed pages
Git-commit: 895749455f6054e0c7b40a6ec449a3ab6db51bdd
Patch-mainline: v5.18-rc1
References: jsc#PED-1294
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@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: "Sierra Guiza, Alejandro (Alex)" <alex.sierra@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Christian Knig <christian.koenig@amd.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
include/linux/mm.h | 33 ++++++++++-----------------------
mm/memremap.c | 20 +++++++++-----------
mm/swap.c | 10 +---------
3 files changed, 20 insertions(+), 43 deletions(-)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1151,33 +1151,24 @@ 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)
@@ -1230,15 +1221,11 @@ static inline void put_page(struct page
page = compound_head(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(page)) {
- put_devmap_managed_page(page);
+ if (put_devmap_managed_page(page))
return;
- }
if (put_page_testzero(page))
__put_page(page);
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -531,24 +531,22 @@ 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
+++ b/mm/swap.c
@@ -913,16 +913,8 @@ 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;