linux-kernel - Re: [PATCH] mm: Fix a race during split THP

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Message-ID: <20201009132704.GS20115@casper.infradead.org>
Date:   Fri, 9 Oct 2020 14:27:04 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     "Huang, Ying" <ying.huang@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Rafael Aquini <aquini@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [PATCH] mm: Fix a race during split THP

On Fri, Oct 09, 2020 at 03:36:47PM +0800, Huang, Ying wrote:
> +	if (PageSwapCache(head)) {
> +		swp_entry_t entry = { .val = page_private(head) };
> +
> +		split_swap_cluster(entry);
> +	}
...
> -		if (PageSwapCache(head)) {
> -			swp_entry_t entry = { .val = page_private(head) };
> -
> -			ret = split_swap_cluster(entry);

Are we sure split_swap_cluster() can't fail?  Or if it does fail, it's
OK to continue with the split and not report the error?