From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) (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 8C36E367F35 for ; Fri, 13 Mar 2026 10:40:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773398449; cv=none; b=TpU8oNzk0/h03LQFqApGG4uWRiIz6dglWFt3NKFJQq3EX+qFfdkqKYDJEoFji283MHf2cFP4c5pCmboxWhZRMgGSS1OfWLPoq+R75n3Etm13vMNB0uQ3NUkOfZ/60tW2Yb4AtI8XWoys9dgz9AotCCqOYCbEzno71ljaJsQJ6Vk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773398449; c=relaxed/simple; bh=dIlaKi4NWjNsJGDT++udD7TlSA304Lh7dGgoYE6KiXk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fU9ukfRgW7PFsXV1Tk2SpTFRGdi/Yf02XUtfn2goGcgmbNfr4be+dwAPDdIWn4NxZQb+rTiGjuVd8me3NJr+dy9nOXrwoda2ovmzwry+qVQT4jhIMJBj6hOPk+rPnLgnXlL0hwb9FDsEZVYReg99FTeKssuRnpqaqNiIyXZE9s8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=jORxnQ/C; arc=none smtp.client-ip=91.218.175.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="jORxnQ/C" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1773398435; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3bRz0a5rDf3B7IZQUMIebticNEhlGjLTFEMcGXq89IU=; b=jORxnQ/CClGmZiyZq5YW/ui3uCz8vIxhsfkcXEcQkLuaZqufBN9zXYt+nV5DXaBTlThPnN O6vuRlNHol4OE/ixrrJ0fAFgtvrTmXUcL5JngaiSvjRnCV7XdPLs2LbV6iMu7vNhpvYawx fqBAxtD6NBt934ZI4NcyFvqw7yG7gRU= Date: Fri, 13 Mar 2026 13:40:29 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v3] mm: migrate: requeue destination folio on deferred split queue Content-Language: en-GB To: Andrew Morton , SeongJae Park Cc: npache@redhat.com, david@kernel.org, ziy@nvidia.com, willy@infradead.org, linux-mm@kvack.org, matthew.brost@intel.com, joshua.hahnjy@gmail.com, hannes@cmpxchg.org, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, linux-kernel@vger.kernel.org, kernel-team@meta.com, richard.weiyang@gmail.com, stable@vger.kernel.org References: <20260312104723.1351321-1-usama.arif@linux.dev> <20260313001630.80081-1-sj@kernel.org> <20260312175241.01b876f3b325264f43312d79@linux-foundation.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Usama Arif In-Reply-To: <20260312175241.01b876f3b325264f43312d79@linux-foundation.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 13/03/2026 03:52, Andrew Morton wrote: > On Thu, 12 Mar 2026 17:16:30 -0700 SeongJae Park wrote: > >>> By the time migrate_folio_move() runs, partially mapped folios without a >>> pin have already been split by migrate_pages_batch(). So only two cases >>> remain on the deferred list at this point: >>> 1. Partially mapped folios with a pin (split failed). >>> 2. Fully mapped but potentially underused folios. >>> The recorded partially_mapped state is forwarded to deferred_split_folio() >>> so that the destination folio is correctly re-queued in both cases. >>> >>> Reported-by: Johannes Weiner >>> Fixes: dafff3f4c850 ("mm: split underused THPs") >> >> Seems the commit is merged in 6.12. And I assume the user impact on >> THP-shrinker enabled systems is visible. If so, should we Cc stable@ ? > > I think the user impact should be visible to backport, but the > changelog is elusive on details? > The original patches added THPs to deferred_list at fault/collapse, they got removed but not added back to the list after migration. This patch adds them to the deferred_list on migration. The user would not expect the THPs to get removed from deferred_list on migration, so this fixes user expectations. I have CC-ed stable@vger.kernel.org to this email. Should I resend the patch with CC stable in commit message?