From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5259F47AF5D; Wed, 1 Apr 2026 18:51:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775069498; cv=none; b=mzBupjipa3J5MOhD8qOcTfzdHaBhnPtBQyLdMOUMpGl2HdHEKRcaIqDVFJP0ARJTS8lZcuvI5mbsbdArnnDuQo38I3msduSmSi75yHiyD6nVpDwSioTYzSm9B5Z31I8ldmhw81SzqvtMjmASAqm9x3x6Oc3cr5XVIvWF94GJKPc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775069498; c=relaxed/simple; bh=2uWJMj3r0MZ0oqzNatIfZ8p/N+aYGDnHXLEESrphDXQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Pc2NkbpsscO5tO9EJZpoejetdkjQkigm/UCuMD1qPBC++IlqZ/RgykTHfcwpNQ+LsYQN+H5iurwunIZ5piQZmZANFu0u9nuYw4RSXHlJRtLWohuA1KlmKC6pPIicweAcevzjY9OfPZqlJ41Gdm3e2C3HR7FpVx5mt3FJMU6/zpI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FGdDqaE/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FGdDqaE/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ABE51C4CEF7; Wed, 1 Apr 2026 18:51:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775069498; bh=2uWJMj3r0MZ0oqzNatIfZ8p/N+aYGDnHXLEESrphDXQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=FGdDqaE/D/FmAk9cntlrbwEh3fEtBVRB0F5WcDmGGHy8v9P58md1DLQy8K4K9Tu7m 5Av4KtNqDVe1CZIehIXZcgGHpJ92y0emq9m+1i/KLNuReQcMqKfhx4zLoMql4YUtfg XYIsoVRrBvYH57tP1mbdBm6VT7hGFFcoAAHbZHP5oYhx0ctRSXGwTTXmUc8d8j2GUc DQOIkvunvxOMkIVtBV/1pKRWBI5kR3Xejsm9T91/IpYOp/i2d1THTEjUDVRXQ8wC9V iuiqspBDmYtzuXEsCeeo8ji6JyJzXaSLa5EjghCIEf47TGOanI0bZ5RNhbP3EO5Gck NuzB9E4tjUZCg== Message-ID: <816a5813-3d2e-4d2b-9aa8-8ef20b3c6f7a@kernel.org> Date: Wed, 1 Apr 2026 20:51:30 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-unstable 1/1] mm: fix deferred split queue races during migration To: Lance Yang , akpm@linux-foundation.org Cc: ljs@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, richard.weiyang@gmail.com, usama.arif@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kartikey406@gmail.com, syzbot+a7067a757858ac8eb085@syzkaller.appspotmail.com, stable@vger.kernel.org References: <20260401131032.13011-1-lance.yang@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/1/26 15:10, Lance Yang wrote: > From: Lance Yang > > migrate_folio_move() records the deferred split queue state from src and > replays it on dst. Replaying it after remove_migration_ptes(src, dst, 0) > makes dst visible before it is requeued, so a concurrent rmap-removal path > can mark dst partially mapped and trip the WARN in deferred_split_folio(). > > Move the requeue before remove_migration_ptes() so dst is back on the > deferred split queue before it becomes visible again. > > Because migration still holds dst locked at that point, teach > deferred_split_scan() to requeue a folio when folio_trylock() fails. > Otherwise a fully mapped underused folio can be dequeued by the shrinker > and silently lost from split_queue. > > Link: https://syzkaller.appspot.com/bug?extid=a7067a757858ac8eb085 > Fixes: 8a8ca142a488 ("mm: migrate: requeue destination folio on deferred split queue") > Reported-by: syzbot+a7067a757858ac8eb085@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/linux-mm/69ccb65b.050a0220.183828.003a.GAE@google.com/ > Cc: > Suggested-by: David Hildenbrand (Arm) > Signed-off-by: Lance Yang > --- LGTM, thanks! Acked-by: David Hildenbrand (Arm) -- Cheers, David