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author | 2023-06-08 18:42:40 -0700 | |
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committer | 2023-06-19 16:19:18 -0700 | |
commit | 895f5ee464cc90a5f38163720431c849e93ead97 (patch) | |
tree | c092df7f70c56d320fcd262598c83a7a1d0a2a23 /mm | |
parent | mm/huge_memory: split huge pmd under one pte_offset_map() (diff) | |
download | linux-895f5ee464cc90a5f38163720431c849e93ead97.tar.gz linux-895f5ee464cc90a5f38163720431c849e93ead97.tar.bz2 linux-895f5ee464cc90a5f38163720431c849e93ead97.zip |
mm/khugepaged: allow pte_offset_map[_lock]() to fail
__collapse_huge_page_swapin(): don't drop the map after every pte, it only
has to be dropped by do_swap_page(); give up if pte_offset_map() fails;
trace_mm_collapse_huge_page_swapin() at the end, with result; fix comment
on returned result; fix vmf.pgoff, though it's not used.
collapse_huge_page(): use pte_offset_map_lock() on the _pmd returned from
clearing; allow failure, but it should be impossible there.
hpage_collapse_scan_pmd() and collapse_pte_mapped_thp() allow for
pte_offset_map_lock() failure.
Link: https://lkml.kernel.org/r/6513e85-d798-34ec-3762-7c24ffb9329@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/khugepaged.c | 72 |
1 files changed, 49 insertions, 23 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 2d206e62d358..04c22b5309d7 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -991,9 +991,8 @@ static int check_pmd_still_valid(struct mm_struct *mm, * Only done if hpage_collapse_scan_pmd believes it is worthwhile. * * Called and returns without pte mapped or spinlocks held. - * Note that if false is returned, mmap_lock will be released. + * Returns result: if not SCAN_SUCCEED, mmap_lock has been released. */ - static int __collapse_huge_page_swapin(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, @@ -1002,23 +1001,35 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm, int swapped_in = 0; vm_fault_t ret = 0; unsigned long address, end = haddr + (HPAGE_PMD_NR * PAGE_SIZE); + int result; + pte_t *pte = NULL; for (address = haddr; address < end; address += PAGE_SIZE) { struct vm_fault vmf = { .vma = vma, .address = address, - .pgoff = linear_page_index(vma, haddr), + .pgoff = linear_page_index(vma, address), .flags = FAULT_FLAG_ALLOW_RETRY, .pmd = pmd, }; - vmf.pte = pte_offset_map(pmd, address); - vmf.orig_pte = *vmf.pte; - if (!is_swap_pte(vmf.orig_pte)) { - pte_unmap(vmf.pte); - continue; + if (!pte++) { + pte = pte_offset_map(pmd, address); + if (!pte) { + mmap_read_unlock(mm); + result = SCAN_PMD_NULL; + goto out; + } } + + vmf.orig_pte = *pte; + if (!is_swap_pte(vmf.orig_pte)) + continue; + + vmf.pte = pte; ret = do_swap_page(&vmf); + /* Which unmaps pte (after perhaps re-checking the entry) */ + pte = NULL; /* * do_swap_page returns VM_FAULT_RETRY with released mmap_lock. @@ -1027,24 +1038,29 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm, * resulting in later failure. */ if (ret & VM_FAULT_RETRY) { - trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); /* Likely, but not guaranteed, that page lock failed */ - return SCAN_PAGE_LOCK; + result = SCAN_PAGE_LOCK; + goto out; } if (ret & VM_FAULT_ERROR) { mmap_read_unlock(mm); - trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); - return SCAN_FAIL; + result = SCAN_FAIL; + goto out; } swapped_in++; } + if (pte) + pte_unmap(pte); + /* Drain LRU add pagevec to remove extra pin on the swapped in pages */ if (swapped_in) lru_add_drain(); - trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); - return SCAN_SUCCEED; + result = SCAN_SUCCEED; +out: + trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, result); + return result; } static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm, @@ -1144,9 +1160,6 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, address + HPAGE_PMD_SIZE); mmu_notifier_invalidate_range_start(&range); - pte = pte_offset_map(pmd, address); - pte_ptl = pte_lockptr(mm, pmd); - pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ /* * This removes any huge TLB entry from the CPU so we won't allow @@ -1161,13 +1174,18 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, mmu_notifier_invalidate_range_end(&range); tlb_remove_table_sync_one(); - spin_lock(pte_ptl); - result = __collapse_huge_page_isolate(vma, address, pte, cc, - &compound_pagelist); - spin_unlock(pte_ptl); + pte = pte_offset_map_lock(mm, &_pmd, address, &pte_ptl); + if (pte) { + result = __collapse_huge_page_isolate(vma, address, pte, cc, + &compound_pagelist); + spin_unlock(pte_ptl); + } else { + result = SCAN_PMD_NULL; + } if (unlikely(result != SCAN_SUCCEED)) { - pte_unmap(pte); + if (pte) + pte_unmap(pte); spin_lock(pmd_ptl); BUG_ON(!pmd_none(*pmd)); /* @@ -1251,6 +1269,11 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, memset(cc->node_load, 0, sizeof(cc->node_load)); nodes_clear(cc->alloc_nmask); pte = pte_offset_map_lock(mm, pmd, address, &ptl); + if (!pte) { + result = SCAN_PMD_NULL; + goto out; + } + for (_address = address, _pte = pte; _pte < pte + HPAGE_PMD_NR; _pte++, _address += PAGE_SIZE) { pte_t pteval = *_pte; @@ -1620,8 +1643,10 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, * lockless_pages_from_mm() and the hardware page walker can access page * tables while all the high-level locks are held in write mode. */ - start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); result = SCAN_FAIL; + start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); + if (!start_pte) + goto drop_immap; /* step 1: check all mapped PTEs are to the right huge page */ for (i = 0, addr = haddr, pte = start_pte; @@ -1695,6 +1720,7 @@ drop_hpage: abort: pte_unmap_unlock(start_pte, ptl); +drop_immap: i_mmap_unlock_write(vma->vm_file->f_mapping); goto drop_hpage; } |