From a7a6c576e137c61229c1d0958d688c028a20331c Mon Sep 17 00:00:00 2001 From: Alex Sierra Date: Tue, 31 May 2022 15:00:30 -0500 Subject: [PATCH] mm: handling Non-LRU pages returned by vm_normal_pages With DEVICE_COHERENT, we'll soon have vm_normal_pages() return device-managed anonymous pages that are not LRU pages. Although they behave like normal pages for purposes of mapping in CPU page, and for COW. They do not support LRU lists, NUMA migration or THP. We also introduced a FOLL_LRU flag that adds the same behaviour to follow_page and related APIs, to allow callers to specify that they expect to put pages on an LRU list. Link: https://lkml.kernel.org/r/20220531200041.24904-3-alex.sierra@amd.com Signed-off-by: Alex Sierra Acked-by: Felix Kuehling Reviewed-by: Alistair Popple Cc: Christoph Hellwig Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Jerome Glisse Cc: Matthew Wilcox Cc: Ralph Campbell Signed-off-by: Andrew Morton --- fs/proc/task_mmu.c | 2 +- include/linux/mm.h | 3 ++- mm/gup.c | 6 +++++- mm/huge_memory.c | 2 +- mm/khugepaged.c | 9 ++++++--- mm/ksm.c | 6 +++--- mm/madvise.c | 4 ++-- mm/memory.c | 9 ++++++++- mm/mempolicy.c | 2 +- mm/migrate.c | 4 ++-- mm/mlock.c | 2 +- mm/mprotect.c | 2 +- 12 files changed, 33 insertions(+), 18 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index f9c9abb50bb7..37ccb5c9f4f8 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1800,7 +1800,7 @@ static struct page *can_gather_numa_stats(pte_t pte, struct vm_area_struct *vma, return NULL; page = vm_normal_page(vma, addr, pte); - if (!page) + if (!page || is_zone_device_page(page)) return NULL; if (PageReserved(page)) diff --git a/include/linux/mm.h b/include/linux/mm.h index 7f2d3ec50718..62cf14d3295c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -601,7 +601,7 @@ struct vm_operations_struct { #endif /* * Called by vm_normal_page() for special PTEs to find the - * page for @addr. This is useful if the default behavior + * page for @addr. This is useful if the default behavior * (using pte_page()) would not find the correct page. */ struct page *(*find_special_page)(struct vm_area_struct *vma, @@ -2950,6 +2950,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, #define FOLL_NUMA 0x200 /* force NUMA hinting page fault */ #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */ #define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */ +#define FOLL_LRU 0x1000 /* return only LRU (anon or page cache) */ #define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */ #define FOLL_COW 0x4000 /* internal GUP flag */ #define FOLL_ANON 0x8000 /* don't do file mappings */ diff --git a/mm/gup.c b/mm/gup.c index 4ec77f68c6c1..67cc836eb1b5 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -532,7 +532,11 @@ retry: } page = vm_normal_page(vma, address, pte); - if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) { + if ((flags & FOLL_LRU) && ((page && is_zone_device_page(page)) || + (!page && pte_devmap(pte)))) { + page = ERR_PTR(-EEXIST); + goto out; + } else if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) { /* * Only return device mapping pages in the FOLL_GET or FOLL_PIN * case since they are only valid while holding the pgmap diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f44ffd3bbfae..41264755c1b6 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2905,7 +2905,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start, } /* FOLL_DUMP to ignore special (like zero) pages */ - page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); + page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP | FOLL_LRU); if (IS_ERR(page)) continue; diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 637bfecd6bf5..476d79360101 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -618,7 +618,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, goto out; } page = vm_normal_page(vma, address, pteval); - if (unlikely(!page)) { + if (unlikely(!page) || unlikely(is_zone_device_page(page))) { result = SCAN_PAGE_NULL; goto out; } @@ -1267,7 +1267,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, writable = true; page = vm_normal_page(vma, _address, pteval); - if (unlikely(!page)) { + if (unlikely(!page) || unlikely(is_zone_device_page(page))) { result = SCAN_PAGE_NULL; goto out_unmap; } @@ -1479,7 +1479,8 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) goto abort; page = vm_normal_page(vma, addr, *pte); - + if (WARN_ON_ONCE(page && is_zone_device_page(page))) + page = NULL; /* * Note that uprobe, debugger, or MAP_PRIVATE may change the * page table, but the new page will not be a subpage of hpage. @@ -1497,6 +1498,8 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) if (pte_none(*pte)) continue; page = vm_normal_page(vma, addr, *pte); + if (WARN_ON_ONCE(page && is_zone_device_page(page))) + goto abort; page_remove_rmap(page, vma, false); } diff --git a/mm/ksm.c b/mm/ksm.c index 4e3d794f6b09..a5cd341f7870 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -474,7 +474,7 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr) do { cond_resched(); page = follow_page(vma, addr, - FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE); + FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE | FOLL_LRU); if (IS_ERR_OR_NULL(page)) break; if (PageKsm(page)) @@ -559,7 +559,7 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item) if (!vma) goto out; - page = follow_page(vma, addr, FOLL_GET); + page = follow_page(vma, addr, FOLL_GET | FOLL_LRU); if (IS_ERR_OR_NULL(page)) goto out; if (PageAnon(page)) { @@ -2310,7 +2310,7 @@ next_mm: while (ksm_scan.address < vma->vm_end) { if (ksm_test_exit(mm)) break; - *page = follow_page(vma, ksm_scan.address, FOLL_GET); + *page = follow_page(vma, ksm_scan.address, FOLL_GET | FOLL_LRU); if (IS_ERR_OR_NULL(*page)) { ksm_scan.address += PAGE_SIZE; cond_resched(); diff --git a/mm/madvise.c b/mm/madvise.c index 12e8010c766c..7a8af04069b3 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -421,7 +421,7 @@ regular_page: continue; page = vm_normal_page(vma, addr, ptent); - if (!page) + if (!page || is_zone_device_page(page)) continue; /* @@ -639,7 +639,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, } page = vm_normal_page(vma, addr, ptent); - if (!page) + if (!page || is_zone_device_page(page)) continue; /* diff --git a/mm/memory.c b/mm/memory.c index fdfc119f181d..c905fabddeec 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -633,6 +633,13 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, if (is_zero_pfn(pfn)) return NULL; if (pte_devmap(pte)) +/* + * NOTE: New uers of ZONE_DEVICE will not set pte_devmap() and will have + * refcounts incremented on their struct pages when they are inserted into + * PTEs, thus they are safe to return here. Legacy ZONE_DEVICE pages that set + * pte_devmap() do not have refcounts. Example of legacy ZONE_DEVICE is + * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers. + */ return NULL; print_bad_pte(vma, addr, pte, NULL); @@ -4708,7 +4715,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) pte = pte_modify(old_pte, vma->vm_page_prot); page = vm_normal_page(vma, vmf->address, pte); - if (!page) + if (!page || is_zone_device_page(page)) goto out_map; /* TODO: handle PTE-mapped THP */ diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 201b043e96f1..b879a326bfb7 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -524,7 +524,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr, if (!pte_present(*pte)) continue; page = vm_normal_page(vma, addr, *pte); - if (!page) + if (!page || is_zone_device_page(page)) continue; /* * vm_normal_page() filters out zero pages, but there might diff --git a/mm/migrate.c b/mm/migrate.c index d49797b3ad80..085c8f10fb79 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1622,7 +1622,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr, goto out; /* FOLL_DUMP to ignore special (like zero) pages */ - page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); + page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP | FOLL_LRU); err = PTR_ERR(page); if (IS_ERR(page)) @@ -1814,7 +1814,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, goto set_status; /* FOLL_DUMP to ignore special (like zero) pages */ - page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); + page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP | FOLL_LRU); err = PTR_ERR(page); if (IS_ERR(page)) diff --git a/mm/mlock.c b/mm/mlock.c index c41604ba5197..43d19a1f28eb 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -333,7 +333,7 @@ static int mlock_pte_range(pmd_t *pmd, unsigned long addr, if (!pte_present(*pte)) continue; page = vm_normal_page(vma, addr, *pte); - if (!page) + if (!page || is_zone_device_page(page)) continue; if (PageTransCompound(page)) continue; diff --git a/mm/mprotect.c b/mm/mprotect.c index 27fb652151e4..f7b31657d1da 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -95,7 +95,7 @@ static unsigned long change_pte_range(struct mmu_gather *tlb, continue; page = vm_normal_page(vma, addr, oldpte); - if (!page || PageKsm(page)) + if (!page || is_zone_device_page(page) || PageKsm(page)) continue; /* Also skip shared copy-on-write pages */ -- 2.50.1