| Message ID | 1474992504-20133-10-git-send-email-jack@suse.cz (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Tue, Sep 27, 2016 at 06:08:13PM +0200, Jan Kara wrote: > Introduce function 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. > > Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
On Tue, Sep 27, 2016 at 06:08:13PM +0200, Jan Kara wrote: > Introduce function 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. > > Signed-off-by: Jan Kara <jack@suse.cz> > --- > diff --git a/mm/memory.c b/mm/memory.c > index 17db88a38e8a..f54cfad7fe04 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3029,6 +3029,36 @@ int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg, > return 0; > } > > + > +/** > + * 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. > + */ > +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)) Oh, sorry, I did have one bit of feedback. Maybe added parens around the flag check for readability: if ((vmf->flags & FAULT_FLAG_WRITE) && !(vmf->vma->vm_flags & VM_SHARED)) Aside from that one nit: Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
On Mon 17-10-16 11:40:42, Ross Zwisler wrote: > On Tue, Sep 27, 2016 at 06:08:13PM +0200, Jan Kara wrote: > > + /* Did we COW the page? */ > > + if (vmf->flags & FAULT_FLAG_WRITE && !(vmf->vma->vm_flags & VM_SHARED)) > > Oh, sorry, I did have one bit of feedback. Maybe added parens around the flag > check for readability: > > if ((vmf->flags & FAULT_FLAG_WRITE) && !(vmf->vma->vm_flags & VM_SHARED)) Fixed. > Aside from that one nit: > > Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Thanks! Honza
diff --git a/include/linux/mm.h b/include/linux/mm.h index faa77b15e9a6..919ebdd27f1e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -622,6 +622,7 @@ 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 /* diff --git a/mm/memory.c b/mm/memory.c index 17db88a38e8a..f54cfad7fe04 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3029,6 +3029,36 @@ int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg, return 0; } + +/** + * 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. + */ +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); @@ -3174,9 +3204,7 @@ 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); @@ -3215,9 +3243,7 @@ static int do_cow_fault(struct vm_fault *vmf) copy_user_highpage(new_page, vmf->page, vmf->address, vma); __SetPageUptodate(new_page); - ret |= alloc_set_pte(vmf, memcg, new_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); @@ -3258,9 +3284,7 @@ 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);
Introduce function 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. Signed-off-by: Jan Kara <jack@suse.cz> --- include/linux/mm.h | 1 + mm/memory.c | 42 +++++++++++++++++++++++++++++++++--------- 2 files changed, 34 insertions(+), 9 deletions(-)