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Commit 9118c0cb authored by Jan Kara's avatar Jan Kara Committed by Linus Torvalds
Browse files

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: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3917048d

include/linux/mm.h

+1 −0
Original line number Diff line number Diff line
@@ -620,6 +620,7 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 


int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,

		struct page *page);

int finish_fault(struct vm_fault *vmf);

#endif



/*

mm/memory.c

+35 −9
Original line number Diff line number Diff line
@@ -3074,6 +3074,38 @@ int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg, 
	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);