Re: [PATCH v2 5/6] mm: Handle read faults under the VMA lock

[Suren Baghdasaryan <surenb@google.com>]

On Fri, Oct 6, 2023 at 12:53 PM Matthew Wilcox (Oracle)
<willy@infradead.org> wrote:
>
> Most file-backed faults are already handled through ->map_pages(),
> but if we need to do I/O we'll come this way.  Since filemap_fault()
> is now safe to be called under the VMA lock, we can handle these faults
> under the VMA lock now.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Suren Baghdasaryan <surenb@google.com>

> ---
>  mm/memory.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 938f481df0ab..e615afd28db2 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4617,10 +4617,9 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf)
>                         return ret;
>         }
>
> -       if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
> -               vma_end_read(vmf->vma);
> -               return VM_FAULT_RETRY;
> -       }
> +       ret = vmf_can_call_fault(vmf);
> +       if (ret)
> +               return ret;
>
>         ret = __do_fault(vmf);
>         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
> --
> 2.40.1
>