From: Mani Tofigh <mt4022@columbia.edu>
To: "David Hildenbrand (Arm)" <david@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Chris Li <chrisl@kernel.org>, Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>,
Nhat Pham <nphamcs@gmail.com>, Baoquan He <baoquan.he@linux.dev>,
Barry Song <baohua@kernel.org>,
Youngjun Park <youngjun.park@lge.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
tz2294@columbia.edu, stable@vger.kernel.org
Subject: Re: [PATCH] mm/swapfile: drop a large unmapped swap-in folio in unuse_pte()
Date: Sun, 1 Nov 2026 10:46:11 -0500 [thread overview]
Message-ID: <930e2b99-df87-4aeb-88d0-d12d012edbf1@columbia.edu> (raw)
In-Reply-To: <04ad7001-bdd4-47e1-9a80-5b2464da1044@kernel.org>
On 10/30/26 6:15 PM, David Hildenbrand (Arm) wrote:
> Why is this special to large folios? I guess because a single PTE keeps the
> large folio alive, right?
Yup. For a small folio the one PTE maps all of it so
folio_add_new_anon_rmap() is fine there. For a larger one it marks
every page as mapped and exclusive even though only one PTE got mapped.
> Can you pack the existing handling in do_swap_page() into a helper, pass
> nr_pages, and reuse it here?
Sounds good, I'll do that in v2 and send it against mm/core.git
for-next. One small thing in the helper you suggested though:
the first check should be folio_test_anon() instead of
!folio_test_anon(), otherwise a large non-anon folio would
still get mapped.
Thanks!
Mani
next prev parent reply other threads:[~2026-11-01 15:46 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-30 19:11 Mani Tofigh via B4 Relay
2026-10-30 22:15 ` David Hildenbrand (Arm)
2026-11-01 15:46 ` Mani Tofigh [this message]
2026-11-02 6:53 ` David Hildenbrand (Arm)
2026-10-30 22:54 ` Andrew Morton
2026-10-31 5:54 ` Kairui Song
2026-11-01 15:54 ` Mani Tofigh
2026-10-31 9:34 ` David Hildenbrand (Arm)
2026-10-31 5:54 ` Kairui Song
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