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 1AF941FC101 for ; Fri, 13 Mar 2026 00:52:42 +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=1773363163; cv=none; b=Hs3O+Wu9WV9dKQRNylbisWXjNGdKX/sEkLZhoB8EEkFgAQF9zKE7TVxBeb1W1uDxIAGfQ1wiYKibaZXqKx2j9U23pTjKGKzLTMfqbj+4mmQ5DPc8lNdTT61IUbb2k6TivHmXRm4SYoV5bV9Hz5MBfXcYjmM2oq5NLkfYgTL+0ww= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773363163; c=relaxed/simple; bh=u09tJ6oA8uKQCXuVDskUj3OnLNBy14TubsLkRd25lYM=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=cLSybwHZB3nxoA2nkjHK0CeRxNVmEV90Vyj0aSBYGNy6qTl+S4efJc26yW9NWOUZKtVqXqb9TzGSqKxMLppEZLrkfA4UbQe4qbItjnKxJXpY/1ERLHwE3kUDzAmOR4mXCIrYzRAGyOC+PuxY8+UdmFEtQTHCS2kcxb55JTKwnZ4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=DuWzI4UB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="DuWzI4UB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1141BC4CEF7; Fri, 13 Mar 2026 00:52:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1773363162; bh=u09tJ6oA8uKQCXuVDskUj3OnLNBy14TubsLkRd25lYM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DuWzI4UBSebrvs52L3URsESaYwY6E249CplCTg89RqcP6gHXSWzexwipGvO1ZK7jM j6xn07MpLCY+SpLhFy/kWbOtD7gA3myI9x8NbYqkCJS7LZ0LFf4o10uBCm3fjUKDON cPGcAx3lkMHOAFiEkX2455t7Y26J5F51hDQUBlSM= Date: Thu, 12 Mar 2026 17:52:41 -0700 From: Andrew Morton To: SeongJae Park Cc: Usama Arif , 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 Subject: Re: [PATCH v3] mm: migrate: requeue destination folio on deferred split queue Message-Id: <20260312175241.01b876f3b325264f43312d79@linux-foundation.org> In-Reply-To: <20260313001630.80081-1-sj@kernel.org> References: <20260312104723.1351321-1-usama.arif@linux.dev> <20260313001630.80081-1-sj@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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?