From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B21DD3E44E3 for ; Thu, 9 Jul 2026 08:03:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783584198; cv=none; b=VS0xMMZIk56IhqVzp+132/+gMM4anGVAar+iJNFvXZ/pjT4LRCAVRmxF/iZf/ek2ALnRWrIHV3h9fhxwRrPgi34Hb6O4/le50IYpsZKNPq8E/HQ5OKHkT7UbCr9SMCR6fg7pZLJuaD9L4/LyTy3M7JvZ7/Q+O1SA3+Lm60JWIa0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783584198; c=relaxed/simple; bh=ris/saT/CSP79Kn5MmK1095lVd0H7SYB7ceDybT4tKE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=dlXzbJSTu50UD4V4f+K9zwZUzc0gCMbz7MV5Er7asuWN3re9psP7W7b7awI8XPKj3CWoHav6fxC3l5IabP2UX2LFwWznvICQxUc4PyYgpIya1Yx0VBuEgO9ZYH5Q+0h0jAUdvnVZIwevP9Eaio0ydJwXGAlb0MOOFmPqoPeVZWg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=l1fg/Ke4; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="l1fg/Ke4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 49E4F1F00A3A; Thu, 9 Jul 2026 08:03:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783584197; bh=h5ZMUXMkvr/7WHhhpVtDxbUpZkY1abuvie4G1/u+VcI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=l1fg/Ke4z/FFhff5Njov+OQVa7rzHpXWK45MA/ebH+hWYUEWCOkvhG9FH+6MP8upf DT+WlYGmyLAf+Fl7bm8Yd+tcYXlzOJxa8VWpumeH2G/j+DeFo/KG9uAUHD3pSgGYRi 5ztQu7K620YTfozDColg9z6eKx71L9ADEQj9RK0d481+ERvUAzLjiMLbfjqRNBW5Kf MS3tdlg3PjzyzRSbBoADOtUE/3BqWJNHv4VY1nf5lmu4N9rHqxdNsd2s3lAGHsH+AM b3cKB7ug4okAbiHX0DO4A8r093MKgdQsgQcoIEFL1looLIQxX5/s3W9tsAoc2RmpuH EfyhpT/QHJrkQ== Message-ID: <97d3831f-ce7e-4408-ae0c-60e45d00d69e@kernel.org> Date: Thu, 9 Jul 2026 10:03:12 +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 v2 3/5] mm/huge_memory: add page->private check back in __split_folio_to_order() Content-Language: en-US To: Zi Yan , Andrew Morton , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , David Hildenbrand , Lorenzo Stoakes , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Mike Rapoport , Dennis Zhou , Tejun Heo , Christoph Lameter , Alistair Popple Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260703-keep-subpage-private-zero-at-free-v2-0-2970fe777dd6@nvidia.com> <20260703-keep-subpage-private-zero-at-free-v2-3-2970fe777dd6@nvidia.com> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSNWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBrZXJuZWwub3JnPsLBsAQTAQoAWhYhBKlA1DSZLC6OmRA9UCJPp+fM gqZkBQJqFFy6GxSAAAAAAAQADm1hbnUyLDIuNSsxLjEyLDIsMgIbAwUJGtCBUAULCQgHAwUV CgkICwUWAgMBAAIeBQIXgAAKCRAiT6fnzIKmZJIUEADFx/tREzUImHrEwVHeSvDFmA7tJysI UVrlvrM09E7GIuzphzv7jYmo8n3ANpCczLEVr4G0syYQdTigaZgv3+FQDIIzhKih1IHhu1Ei XHlywNWKnQxxQEUNi5Mwx43wQz5XVw9F1A7gtKBKNtfogO511hAbrzagrYajyQacEJ/+sfhZ 9Da8ltHIXD8pcYaHUfQgEusCgmEd9+KrUwrTbckFKmYq5chuE6yJ4J0EmWknL096jIE6CnzF FRslQ3B1UKDjxVsm1ZHfir5NeWszLkTvGFsddFaWTgh8UycESG6VQzKXjjewXu2pG7YQYRpj QKm1W5X2TkwWkXRBZTmfmbhxIUMh3+zf5wQ463rSmDN/8v81tdqBtAW6rH/kzg1GvkaTHXn0 507yEHFzBksk2viAuIxxr7km8+/KARYLIdGtx30EG8cKzAUZOK6WqxtNCsXUJNrVE8CWrCaD icoNu7Fs1c5hmPHdSTnU48ce67449DdnO4neLSNhRiGlMHJgfJUmgrxu/hcYeOZ3haWmEQ2w uW1Mh01OHi8QZHCEyAbABrPs9GUgccc/4eYXX9hIgxfSkYzn8f+8NuIFPWl/0uTvjgqU29FQ SbzOLxHq9439Ox40G5mS5eZXRGxITYR+6TXvRGI6P/264jvflnr/pDGUttaikU+0W+1uxgKH cmYbEc7ATQRbGTU1AQgAn0H6UrFiWcovkh6EXVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQ La1PQDUi6j00ChlcR66g9/V0sPIcSutacPKfdKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMh FmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCTsTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sf bAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZOrIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq +aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahKtQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4n jQARAQABwsF8BBgBCgAmAhsMFiEEqUDUNJksLo6ZED1QIk+n58yCpmQFAmfIHFQFCRYU6J8A CgkQIk+n58yCpmS2PA//bqN1LfcotmArgElsa+0EGZSQlYgK48pm8WAeTXTngudP9IJ4SuKY HR5RNjHcBeqN+Me0zxRqYzRb8nGanHEkDyf4Im8DQM8d6vbyU+FcPmG4skud4kgS1zMHnlVd SXfSIwKC/hKgdHG8aBV7545Lz9X6Iohea+94wneD0aw/hqF+QWewGZhWJriWAZtvEkzNjQOi 4U9F/trLten/x7bpphDSnDMKJtITbtzATT1Dq7o7VpIUK1nCTQALMuMjKCdi8OdU/+V+R3O4 0PXWvX8qrvqYapVbZ+9KqT74FsuB0Ya9uXwgBF2Q6cRuETZk5vqaqKxzqoQZCO8AOz/58j6O 2RHNy/mZEN+7tJ5Tsq42zVJ4jxsT8b9YplavCMsnBgDeRWhcbYhCyttoL7nYISyWg4kQYZ/P wIV3OuNv2f8iKYsxNsRuClOAF82+gvqOy1/1pprFjy8uo2pkoOrb63aOP3vO5VHnRKgra6dq NcaZ+c6J4H+nEJGi2SkHAUJz5oBzuThvPudLvPA/SK8sKoM01IRxSihev/S/5WLazXB1PGem OCbvzC1IjWJJraxiDJ5IygokapUa2RP7+WBR22skQ3SSl6G107QgWKSyTOGWEaRmV53vxQLV jXuCmzSSasTL60zq5yGrT4/DYQVSNEUiUbG4pYekxJujNeEDkUlky0Y= In-Reply-To: <20260703-keep-subpage-private-zero-at-free-v2-3-2970fe777dd6@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/3/26 15:47, Zi Yan wrote: > page->private should not be set in tail pages. Commit 4265d67e405a > ("mm/migrate_device: add THP splitting during migration") removed it I would say e.g. "a DEBUG_VM check" instead of "it" > without a proper reason[1]. Add it back. > > Link: https://lore.kernel.org/all/13f3fcda-7328-4aa5-afc6-75a294a82b2a@nvidia.com/ [1] > Reviewed-by: Lance Yang > Signed-off-by: Zi Yan Reviewed-by: Vlastimil Babka (SUSE) > --- > mm/huge_memory.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index bdd8635922f96..06d0671cff899 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -3591,6 +3591,13 @@ static void __split_folio_to_order(struct folio *folio, int old_order, > new_folio->mapping = folio->mapping; > new_folio->index = folio->index + i; > > + /* > + * page->private should not be set in tail pages. Warn once > + * if private is unexpectedly set. Do it before swap.val assignment > + * since private overlaps with swap.val. > + */ > + VM_WARN_ON_ONCE_PAGE(new_folio->private, new_head); > + > if (folio_test_swapcache(folio)) > new_folio->swap.val = folio->swap.val + i; > >