diff options
| author | Jan Kara <jack@suse.cz> | 2016-12-14 15:07:42 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-14 16:04:09 -0800 |
| commit | a19e25536ed3a20845f642ce531e10c27fb2add5 (patch) | |
| tree | 7bcc1c969a3138ef3c31c2fb8ae815c96afe4382 | |
| parent | 66a6197c118540d454913eef24d68d7491ab5d5f (diff) | |
| download | linux-a19e25536ed3a20845f642ce531e10c27fb2add5.tar.bz2 | |
mm: change return values of finish_mkwrite_fault()
Currently finish_mkwrite_fault() returns 0 when PTE got changed before
we acquired PTE lock and VM_FAULT_WRITE when we succeeded in modifying
the PTE. This is somewhat confusing since 0 generally means success, it
is also inconsistent with finish_fault() which returns 0 on success.
Change finish_mkwrite_fault() to return 0 on success and VM_FAULT_NOPAGE
when PTE changed. Practically, there should be no behavioral difference
since we bail out from the fault the same way regardless whether we
return 0, VM_FAULT_NOPAGE, or VM_FAULT_WRITE. Also note that
VM_FAULT_WRITE has no effect for shared mappings since the only two
places that check it - KSM and GUP - care about private mappings only.
Generally the meaning of VM_FAULT_WRITE for shared mappings is not well
defined and we should probably clean that up.
Link: http://lkml.kernel.org/r/1479460644-25076-17-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@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>
| -rw-r--r-- | mm/memory.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/mm/memory.c b/mm/memory.c index bbc25da48a18..8b7f0656a921 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2295,10 +2295,10 @@ int finish_mkwrite_fault(struct vm_fault *vmf) */ if (!pte_same(*vmf->pte, vmf->orig_pte)) { pte_unmap_unlock(vmf->pte, vmf->ptl); - return 0; + return VM_FAULT_NOPAGE; } wp_page_reuse(vmf); - return VM_FAULT_WRITE; + return 0; } /* @@ -2341,8 +2341,7 @@ static int wp_page_shared(struct vm_fault *vmf) return tmp; } tmp = finish_mkwrite_fault(vmf); - if (unlikely(!tmp || (tmp & - (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { + if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { unlock_page(vmf->page); put_page(vmf->page); return tmp; |