From: Arjun Roy arjunroy@google.com
commit 7f70c2a68a51496289df163f6969d4db7c383f30 upstream.
Calls to pte_offset_map() in vm_insert_pages() are erroneously not matched with a call to pte_unmap(). This would cause problems on architectures where that is not a no-op.
This patch does away with the non-traditional locking in the existing code, and instead uses pte_offset_map_lock/unlock() as usual, incrementing PTE as necessary. The PTE pointer is kept within bounds since we clamp it with PTRS_PER_PTE.
Link: http://lkml.kernel.org/r/20200618220446.20284-1-arjunroy.kdev@gmail.com Fixes: 8cd3984d81d5 ("mm/memory.c: add vm_insert_pages()") Signed-off-by: Arjun Roy arjunroy@google.com Acked-by: David Rientjes rientjes@google.com Cc: Eric Dumazet edumazet@google.com Cc: Hugh Dickins hughd@google.com Cc: Soheil Hassas Yeganeh soheil@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- mm/memory.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)
--- a/mm/memory.c +++ b/mm/memory.c @@ -1501,7 +1501,7 @@ out: }
#ifdef pte_index -static int insert_page_in_batch_locked(struct mm_struct *mm, pmd_t *pmd, +static int insert_page_in_batch_locked(struct mm_struct *mm, pte_t *pte, unsigned long addr, struct page *page, pgprot_t prot) { int err; @@ -1509,8 +1509,9 @@ static int insert_page_in_batch_locked(s if (!page_count(page)) return -EINVAL; err = validate_page_before_insert(page); - return err ? err : insert_page_into_pte_locked( - mm, pte_offset_map(pmd, addr), addr, page, prot); + if (err) + return err; + return insert_page_into_pte_locked(mm, pte, addr, page, prot); }
/* insert_pages() amortizes the cost of spinlock operations @@ -1520,7 +1521,8 @@ static int insert_pages(struct vm_area_s struct page **pages, unsigned long *num, pgprot_t prot) { pmd_t *pmd = NULL; - spinlock_t *pte_lock = NULL; + pte_t *start_pte, *pte; + spinlock_t *pte_lock; struct mm_struct *const mm = vma->vm_mm; unsigned long curr_page_idx = 0; unsigned long remaining_pages_total = *num; @@ -1539,18 +1541,17 @@ more: ret = -ENOMEM; if (pte_alloc(mm, pmd)) goto out; - pte_lock = pte_lockptr(mm, pmd);
while (pages_to_write_in_pmd) { int pte_idx = 0; const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
- spin_lock(pte_lock); - for (; pte_idx < batch_size; ++pte_idx) { - int err = insert_page_in_batch_locked(mm, pmd, + start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock); + for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) { + int err = insert_page_in_batch_locked(mm, pte, addr, pages[curr_page_idx], prot); if (unlikely(err)) { - spin_unlock(pte_lock); + pte_unmap_unlock(start_pte, pte_lock); ret = err; remaining_pages_total -= pte_idx; goto out; @@ -1558,7 +1559,7 @@ more: addr += PAGE_SIZE; ++curr_page_idx; } - spin_unlock(pte_lock); + pte_unmap_unlock(start_pte, pte_lock); pages_to_write_in_pmd -= batch_size; remaining_pages_total -= batch_size; }