From 9118c0cbd44262d0015568266f314e645ed6b9ce Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 14 Dec 2016 15:07:21 -0800 Subject: mm: factor out functionality to finish page faults Introduce finish_fault() as a helper function for finishing page faults. It is rather thin wrapper around alloc_set_pte() but since we'd want to call this from DAX code or filesystems, it is still useful to avoid some boilerplate code. Link: http://lkml.kernel.org/r/1479460644-25076-10-git-send-email-jack@suse.cz Signed-off-by: Jan Kara Reviewed-by: Ross Zwisler Acked-by: Kirill A. Shutemov Cc: Dan Williams Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 44 +++++++++++++++++++++++++++++++++++--------- 1 file changed, 35 insertions(+), 9 deletions(-) (limited to 'mm') diff --git a/mm/memory.c b/mm/memory.c index 02504cd4ca0e..22f7f6e38515 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3074,6 +3074,38 @@ fault_handled: return ret; } + +/** + * finish_fault - finish page fault once we have prepared the page to fault + * + * @vmf: structure describing the fault + * + * This function handles all that is needed to finish a page fault once the + * page to fault in is prepared. It handles locking of PTEs, inserts PTE for + * given page, adds reverse page mapping, handles memcg charges and LRU + * addition. The function returns 0 on success, VM_FAULT_ code in case of + * error. + * + * The function expects the page to be locked and on success it consumes a + * reference of a page being mapped (for the PTE which maps it). + */ +int finish_fault(struct vm_fault *vmf) +{ + struct page *page; + int ret; + + /* Did we COW the page? */ + if ((vmf->flags & FAULT_FLAG_WRITE) && + !(vmf->vma->vm_flags & VM_SHARED)) + page = vmf->cow_page; + else + page = vmf->page; + ret = alloc_set_pte(vmf, vmf->memcg, page); + if (vmf->pte) + pte_unmap_unlock(vmf->pte, vmf->ptl); + return ret; +} + static unsigned long fault_around_bytes __read_mostly = rounddown_pow_of_two(65536); @@ -3213,9 +3245,7 @@ static int do_read_fault(struct vm_fault *vmf) if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) return ret; - ret |= alloc_set_pte(vmf, NULL, vmf->page); - if (vmf->pte) - pte_unmap_unlock(vmf->pte, vmf->ptl); + ret |= finish_fault(vmf); unlock_page(vmf->page); if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) put_page(vmf->page); @@ -3250,9 +3280,7 @@ static int do_cow_fault(struct vm_fault *vmf) copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma); __SetPageUptodate(vmf->cow_page); - ret |= alloc_set_pte(vmf, vmf->memcg, vmf->cow_page); - if (vmf->pte) - pte_unmap_unlock(vmf->pte, vmf->ptl); + ret |= finish_fault(vmf); if (!(ret & VM_FAULT_DAX_LOCKED)) { unlock_page(vmf->page); put_page(vmf->page); @@ -3293,9 +3321,7 @@ static int do_shared_fault(struct vm_fault *vmf) } } - ret |= alloc_set_pte(vmf, NULL, vmf->page); - if (vmf->pte) - pte_unmap_unlock(vmf->pte, vmf->ptl); + ret |= finish_fault(vmf); if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) { unlock_page(vmf->page); -- cgit v1.2.3