Re: [v2 PATCH 1/2] mm: swap: check if swap backing device is congested or not

[Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>]

On 12/21/18 10:34 AM, Tim Chen wrote:
> On 12/20/18 4:21 PM, Yang Shi wrote:
>
> > --- a/mm/swap_state.c
> > +++ b/mm/swap_state.c
> > @@ -538,11 +538,17 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
> >   	bool do_poll = true, page_allocated;
> >   	struct vm_area_struct *vma = vmf->vma;
> >   	unsigned long addr = vmf->address;
> > +	struct inode *inode = si->swap_file->f_mapping->host;
> >   
> >   	mask = swapin_nr_pages(offset) - 1;
> >   	if (!mask)
> >   		goto skip;
> >   
> > +	if (si->flags & (SWP_BLKDEV | SWP_FS)) {
> Maybe move the inode dereference here:
>
> 		inode = si->swap_file->f_mapping->host;

Yes, it looks better since nobody deference inode except the below code. 
Will fix in v3.

Thanks,
Yang

> > +		if (inode_read_congested(inode))
> > +			goto skip;
> > +	}
> > +
> Thanks.
>
> Tim