On 30/08/2017 07:58, Peter Zijlstra wrote:

On Wed, Aug 30, 2017 at 10:33:50AM +0530, Anshuman Khandual wrote:

quoted

diff --git a/mm/filemap.c b/mm/filemap.c
index a497024..08f3042 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c

@@ -1181,6 +1181,18 @@ int __lock_page_killable(struct page *__page)
 int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
                         unsigned int flags)
 {
+       if (flags & FAULT_FLAG_SPECULATIVE) {
+               if (flags & FAULT_FLAG_KILLABLE) {
+                       int ret;
+
+                       ret = __lock_page_killable(page);
+                       if (ret)
+                               return 0;
+               } else
+                       __lock_page(page);
+               return 1;
+       }
+
        if (flags & FAULT_FLAG_ALLOW_RETRY) {
                /*
                 * CAUTION! In this case, mmap_sem is not released

Yeah, that looks right.

Hum, I'm wondering if FAULT_FLAG_RETRY_NOWAIT should be forced in the
speculative path in that case to match the semantics of
__lock_page_or_retry().

quoted

@@ -4012,17 +4010,7 @@ int handle_speculative_fault(struct mm_struct *mm, unsigned long address,
                goto unlock;
        }

+       if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
                trace_spf_vma_notsup(_RET_IP_, vma, address);
                goto unlock;
        }

As riel pointed out on IRC slightly later, private file maps also need
->anon_vma and those actually have ->vm_ops IIRC so the condition needs
to be slightly more complicated.

Yes I read again the code and lead to the same conclusion.