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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 <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jan Kara 2016-12-14 15:07:21 -08:00 committed by Linus Torvalds
parent 3917048d45
commit 9118c0cbd4
2 changed files with 36 additions and 9 deletions
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1
include/linux/mm.h
View File

@ -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
/*

44
mm/memory.c
View File

@ -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);