From: Jan Kara Date: Wed, 14 Dec 2016 23:07:42 +0000 (-0800) Subject: mm: change return values of finish_mkwrite_fault() X-Git-Tag: MMI-PSA29.97-13-9~6570^2~39 X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=a19e25536ed3a20845f642ce531e10c27fb2add5;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git 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 Acked-by: Kirill A. Shutemov Cc: Ross Zwisler Cc: Dan Williams Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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;