From: "David Hildenbrand (Arm)" <david@kernel.org>
To: xu.xin16@zte.com.cn, hughd@google.com, akpm@linux-foundation.org,
ljs@kernel.org
Cc: michel@lespinasse.org, chengming.zhou@linux.dev,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: ksm: add mremap selftests for ksm_rmap_walk
Date: Wed, 8 Apr 2026 15:19:09 +0200 [thread overview]
Message-ID: <8e34b0a8-836f-44bb-a6b1-703f79c2ded3@kernel.org> (raw)
In-Reply-To: <20260408211552000LDjkQX010NY5GI_er7Qb1@zte.com.cn>
>
> Oh, thanks to David and Hugh's reminder, I now understand the issue Hugh was pointing out, and I also
> see why my current test program incorrectly passes: before migrating the memory page, the
> mremap() operation has already turned a KSM page into an anonymous page, causing the code to
> take rmap_walk_anon instead of rmap_walk_ksm. Therefore, to reproduce the issue Hugh described,
> we only need to add a delay of wait_ksmd_scan_finish_two_truns before migration (after mremap)
>
> — simply wait for ksmd to merge the remapped page back into a KSM page.
>
> such testing code can reproduce what Hugh points out and FAIL to migrate:
>
Cool, please update the test to take that into account, and please also
test with child processes involved (no mremap() in child, only mremap()
before merging in the host).
--
Cheers,
David
prev parent reply other threads:[~2026-04-08 13:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-07 6:08 xu.xin16
2026-04-07 9:43 ` Lorenzo Stoakes (Oracle)
2026-04-07 15:00 ` David Hildenbrand (Arm)
2026-04-08 0:08 ` Hugh Dickins
2026-04-08 7:11 ` David Hildenbrand (Arm)
2026-04-08 13:15 ` xu.xin16
2026-04-08 13:19 ` David Hildenbrand (Arm) [this message]
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