Re: + mm-reclaim-madv_free-pages.patch added to -mm tree

[Minchan Kim]

On Mon, Mar 06, 2017 at 10:49:06AM -0500, Johannes Weiner wrote:

< snip >

> > @@ -1413,20 +1413,24 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> >  			 * Store the swap location in the pte.
> >  			 * See handle_pte_fault() ...
> >  			 */
> > -			VM_BUG_ON_PAGE(!PageSwapCache(page) && PageSwapBacked(page),
> > -				page);
> > +			if (VM_WARN_ON_ONCE(PageSwapBacked(page) &&
> > +						!PageSwapCache(page))) {
> > +				ret = SWAP_FAIL;
> 
> But you're not adding the !swapbacked && swapcache case?
> 
> > +				page_vma_mapped_walk_done(&pvmw);
> > +				break;
> > +			}
> 
> [...]
> 
> > -			/*
> > -			 * swapin page could be clean, it has data stored in
> > -			 * swap. We can't silently discard it without setting
> > -			 * swap entry in the page table.
> > -			 */
> > -			if (!PageDirty(page) && !PageSwapCache(page)) {
> > -				/* It's a freeable page by MADV_FREE */
> > -				dec_mm_counter(mm, MM_ANONPAGES);
> > -				goto discard;
> > -			} else if (!PageSwapBacked(page)) {
> > -				/* dirty MADV_FREE page */
> > +			/* MADV_FREE page check */
> > +			if (!PageSwapBacked(page)) {
> > +				if (!PageDirty(page)) {
> > +					dec_mm_counter(mm, MM_ANONPAGES);
> > +					goto discard;
> > +				}
> 
> Andrew already has this, you might want to send the warning changes as
> a separate patch on top of this one.

Here it goes.