linux-kernel - Re: [PATCH v2 05/15] mm, swap: always lock and check the swap cache folio before use

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Message-ID: <0bbda135-068a-45bd-afd6-3f5cdf4e570d@redhat.com>
Date: Mon, 8 Sep 2025 14:18:17 +0200
From: David Hildenbrand <david@...hat.com>
To: Kairui Song <kasong@...cent.com>, linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 Matthew Wilcox <willy@...radead.org>, Hugh Dickins <hughd@...gle.com>,
 Chris Li <chrisl@...nel.org>, Barry Song <baohua@...nel.org>,
 Baoquan He <bhe@...hat.com>, Nhat Pham <nphamcs@...il.com>,
 Kemeng Shi <shikemeng@...weicloud.com>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>,
 Ying Huang <ying.huang@...ux.alibaba.com>,
 Johannes Weiner <hannes@...xchg.org>, Yosry Ahmed <yosryahmed@...gle.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, Zi Yan <ziy@...dia.com>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 05/15] mm, swap: always lock and check the swap cache
 folio before use


>   
>   		folio_lock(folio);
> +		if (!folio_matches_swap_entry(folio, entry)) {
> +			folio_unlock(folio);
> +			folio_put(folio);
> +			continue;
> +		}
> +

I wonder if we should put that into unuse_pte() instead. It checks for 
other types of races (like the page table entry getting modified) already.

-- 
Cheers

David / dhildenb