diff options
author | Christoph Hellwig <hch@lst.de> | 2022-02-16 15:31:36 +1100 |
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committer | Matthew Wilcox (Oracle) <willy@infradead.org> | 2022-03-03 12:47:33 -0500 |
commit | 27674ef6c73f0c9096a9827dc5d6ba9fc7808422 (patch) | |
tree | 1f57be13e778f35d1ca21902eb4c355d5476b44c /mm/memcontrol.c | |
parent | dc90f0846df4870b6cc8528c31e5c60f18fb68be (diff) | |
download | linux-27674ef6c73f0c9096a9827dc5d6ba9fc7808422.tar.gz linux-27674ef6c73f0c9096a9827dc5d6ba9fc7808422.tar.bz2 linux-27674ef6c73f0c9096a9827dc5d6ba9fc7808422.zip |
mm: remove the extra ZONE_DEVICE struct page refcount
ZONE_DEVICE struct pages have an extra reference count that complicates
the code for put_page() and several places in the kernel that need to
check the reference count to see that a page is not being used (gup,
compaction, migration, etc.). Clean up the code so the reference count
doesn't need to be treated specially for ZONE_DEVICE pages.
Note that this excludes the special idle page wakeup for fsdax pages,
which still happens at refcount 1. This is a separate issue and will
be sorted out later. Given that only fsdax pages require the
notifiacation when the refcount hits 1 now, the PAGEMAP_OPS Kconfig
symbol can go away and be replaced with a FS_DAX check for this hook
in the put_page fastpath.
Based on an earlier patch from Ralph Campbell <rcampbell@nvidia.com>.
Link: https://lkml.kernel.org/r/20220210072828.2930359-8-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.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: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Christian Knig <christian.koenig@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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Diffstat (limited to 'mm/memcontrol.c')
-rw-r--r-- | mm/memcontrol.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2c5032294c9f..8fef072dc1ce 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5503,17 +5503,12 @@ static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, return NULL; /* - * Handle MEMORY_DEVICE_PRIVATE which are ZONE_DEVICE page belonging to - * a device and because they are not accessible by CPU they are store - * as special swap entry in the CPU page table. + * Handle device private pages that are not accessible by the CPU, but + * stored as special swap entries in the page table. */ if (is_device_private_entry(ent)) { page = pfn_swap_entry_to_page(ent); - /* - * MEMORY_DEVICE_PRIVATE means ZONE_DEVICE page and which have - * a refcount of 1 when free (unlike normal page) - */ - if (!page_ref_add_unless(page, 1, 1)) + if (!get_page_unless_zero(page)) return NULL; return page; } |