linux-kernel - Re: [PATCH -v2 0/9] migrate

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Date:   Thu, 12 Jan 2023 20:49:19 -0800
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     "Huang, Ying" <ying.huang@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Zi Yan <ziy@...dia.com>,
        Yang Shi <shy828301@...il.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Oscar Salvador <osalvador@...e.de>,
        Matthew Wilcox <willy@...radead.org>,
        Bharata B Rao <bharata@....com>,
        Alistair Popple <apopple@...dia.com>,
        haoxin <xhao@...ux.alibaba.com>
Subject: Re: [PATCH -v2 0/9] migrate_pages(): batch TLB flushing

On 01/13/23 10:42, Huang, Ying wrote:
> Mike Kravetz <mike.kravetz@...cle.com> writes:
> > On 01/12/23 15:17, Huang, Ying wrote:
> >> Mike Kravetz <mike.kravetz@...cle.com> writes:
> >> > On 01/12/23 08:09, Huang, Ying wrote:
> >
> > Isolated to patch,
> > [PATCH -v2 4/9] migrate_pages: split unmap_and_move() to _unmap() and _move()
> >
> > Actually, recreated/isolated by just applying this series to v6.2-rc3 in an
> > effort to eliminate any possible noise in linux-next.
> >
> > Spent a little time looking at modifications made there, but nothing stood out.
> > Will investigate more as time allows.
> 
> Thank you very much!  That's really helpful.
> 
> Checked that patch again, found that there's an issue about non-lru
> pages.  Do you enable zram in your test system?  Can you try the
> below debug patch on top of

CONFIG_ZRAM=y

> 
> [PATCH -v2 4/9] migrate_pages: split unmap_and_move() to _unmap() and _move()
> 
> The following patches in series need to be rebased for the below
> change.  I will test with zram enabled too.

A quick test with below patch on top of [PATCH -v2 4/9] (without the rest of
the series applied) makes the issue go away.  Thanks!
-- 
Mike Kravetz

> 
> Best Regards,
> Huang, Ying
> 
> ---------------------------8<------------------------------------------------------
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 4c35c2a49574..7153d954b8a2 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1187,10 +1187,13 @@ static int __migrate_folio_move(struct folio *src, struct folio *dst,
>  	int rc;
>  	int page_was_mapped = 0;
>  	struct anon_vma *anon_vma = NULL;
> +	bool is_lru = !__PageMovable(&src->page);
>  
>  	__migrate_folio_extract(dst, &page_was_mapped, &anon_vma);
>  
>  	rc = move_to_new_folio(dst, src, mode);
> +	if (!unlikely(is_lru))
> +		goto out_unlock_both;
>  
>  	/*
>  	 * When successful, push dst to LRU immediately: so that if it
> @@ -1211,6 +1214,7 @@ static int __migrate_folio_move(struct folio *src, struct folio *dst,
>  		remove_migration_ptes(src,
>  			rc == MIGRATEPAGE_SUCCESS ? dst : src, false);
>  
> +out_unlock_both:
>  	folio_unlock(dst);
>  	/* Drop an anon_vma reference if we took one */
>  	if (anon_vma)