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

[Yang Shi]

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