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References: <20220204195852.1751729-1-willy@infradead.org> <20220204195852.1751729-52-willy@infradead.org>
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From:   Mauricio Faria de Oliveira <mfo@canonical.com>
Date:   Wed, 9 Feb 2022 11:24:34 -0300
Message-ID: <CAO9xwp2+3Sh-X8xcukLxp5NE3pLWTx=KqVhivDB33W1Xci7uHQ@mail.gmail.com>
Subject: Re: [PATCH 51/75] mm/rmap: Convert try_to_unmap() to take a folio
To:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
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Hi Andrew and Matthew,

On Fri, Feb 4, 2022 at 5:00 PM Matthew Wilcox (Oracle)
<willy@infradead.org> wrote:
>
> Change both callers and the worker function try_to_unmap_one().
...
> diff --git a/mm/rmap.c b/mm/rmap.c
...
> @@ -1598,8 +1602,8 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>                         }
>
>                         /* MADV_FREE page check */
> -                       if (!PageSwapBacked(page)) {
> -                               if (!PageDirty(page)) {
> +                       if (!folio_test_swapbacked(folio)) {
> +                               if (!folio_test_dirty(folio)) {
>                                         /* Invalidate as we cleared the pte */
>                                         mmu_notifier_invalidate_range(mm,
>                                                 address, address + PAGE_SIZE);
> @@ -1608,11 +1612,11 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>                                 }
>
>                                 /*
> -                                * If the page was redirtied, it cannot be
> +                                * If the folio was redirtied, it cannot be
>                                  * discarded. Remap the page to page table.
>                                  */
>                                 set_pte_at(mm, address, pvmw.pte, pteval);
> -                               SetPageSwapBacked(page);
> +                               folio_set_swapbacked(folio);
>                                 ret = false;
>                                 page_vma_mapped_walk_done(&pvmw);
>                                 break;
...

This conflicts with patch [1], currently in mmotm, and I'll send
another version anyway.
Should that patch be on top of these folio changes, or the other way around?

The latter would help w/ the stable backports that don't have folios
yet, but I can
send backports there as well; not a problem.

Thanks,

[1] https://lkml.kernel.org/r/20220131230255.789059-1-mfo@canonical.com
[PATCH v3] mm: fix race between MADV_FREE reclaim and blkdev direct IO read

-- 
Mauricio Faria de Oliveira