linux-kernel - Re: [PATCH v3 30/34] mm: Use flush_icache_pages() in do_set

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Date:   Fri, 3 Mar 2023 16:02:11 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     linux-mm@...ck.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 30/34] mm: Use flush_icache_pages() in do_set_pmd()

On Fri, Mar 03, 2023 at 04:02:01PM +0200, Mike Rapoport wrote:
> On Tue, Feb 28, 2023 at 09:37:33PM +0000, Matthew Wilcox (Oracle) wrote:
> > Push the iteration over each page down to the architectures (many
> > can flush the entire THP without iteration).
> > 
> > Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> > ---
> >  mm/memory.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/mm/memory.c b/mm/memory.c
> > index bfa3100ec5a3..69e844d5f75c 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -4222,8 +4222,7 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
> >  	if (unlikely(!pmd_none(*vmf->pmd)))
> >  		goto out;
> >  
> > -	for (i = 0; i < HPAGE_PMD_NR; i++)
> > -		flush_icache_page(vma, page + i);
> > +	flush_icache_pages(vma, page, HPAGE_PMD_NR);
> >  
> >  	entry = mk_huge_pmd(page, vma->vm_page_prot);
> >  	if (write)
> > -- 
> > 2.39.1
> 
> I get this:
> 
>   CC      mm/memory.o
> /home/mike/git/linux/mm/memory.c: In function 'do_set_pmd':
> /home/mike/git/linux/mm/memory.c:4191:13: warning: unused variable 'i' [-Wunused-variable]
>  4191 |         int i;

Yep, caught that one last night.  My build test must have been with a
config that didn't include THP.  Thanks.