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 B771512E1DC; Tue, 16 Jun 2026 04:15:31 +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=1781583332; cv=none; b=DX8zCvYhzRuRCou7NCQ55bLzSouvzIxLQXamS46ncK5iX+sBXmzcZODI1B9BKJZUjb29YWHCabXO+atLSHvF26aJ9mJzgPRxcKrLNr11Orpi4m0SeJDcppF/kIT0245n69iV8iK1aXHMBt6HMqNlF1zkOuxcTFmJW62CG3THlkQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781583332; c=relaxed/simple; bh=9V50T2TGForvKAGA9bkgMEBL/WX0swsTGfhoJK781M8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=DP+lQYdw0zsJfNmP/+dVBEbgtix9eTvbx+adV6mtNjtSoo/alT2YiJ9zYqFRP5TKz0pbYjB/WSj9qXIyoArZVHElww5Emx6IcTQR/aQvIo+P5fIOl3sky08Y5CMXkbP5Z5iqxn4Wg1OnYMlPl1dPcVHJZVRn4z7ZBoLy3o1xWuQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aIwhwBAH; 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="aIwhwBAH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85CCB1F000E9; Tue, 16 Jun 2026 04:15:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781583331; bh=9V50T2TGForvKAGA9bkgMEBL/WX0swsTGfhoJK781M8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=aIwhwBAHPg3M703IIHHnlJiKWziml6P54SieHjlDAaUaYCWOHuA08vSGeOSsG5TG/ 8EbmwnFRHrYKUSf5fpnWutO6D+26FqtT0LNhFMGQHXKcBqEQ28Z7YItySS9Ffwm7TX JPDcYGfG2fzOjOPqLrh8h+WoXzxVzYOl4YPbqFXfeb0TlIr6315dFC0GD6QlNlFpxO eR8yFBEg1f1fuY7zi1NswXugZFGzw3LwSj6WVVNgpIHzZ1ujUlddo6d6s9n2CHg28r S45VGlcjNxhKXyJpEQnXRh/Qs0R9YxOXnvk2ZIgqiVNxbq2JWolSjIv14hhEQwYZ9Z j/aFoyeTuwlJw== Message-ID: <94eaac52-30a9-4607-a9e9-b2401fe7224f@kernel.org> Date: Tue, 16 Jun 2026 13:15:21 +0900 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/5] mm/slub: preserve previous object lifetime To: Pengpeng Hou , "Vlastimil Babka (SUSE)" , Andrew Morton , linux-mm@kvack.org Cc: Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , David Hildenbrand , Lorenzo Stoakes , liam@infradead.org, Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Shuah Khan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260611063926.38111-1-pengpeng@iscas.ac.cn> <55b1b674-6487-4585-8a0d-919373e66d3a@kernel.org> <763e61e9-9270-4057-938f-daf9184a41ae@kernel.org> <20260615061202.23715-1-pengpeng@iscas.ac.cn> Content-Language: en-US From: Harry Yoo In-Reply-To: <20260615061202.23715-1-pengpeng@iscas.ac.cn> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------rQympXZWzOdztZ7GV117DY9T" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --------------rQympXZWzOdztZ7GV117DY9T Content-Type: multipart/mixed; boundary="------------G4FEeR7cIx4Wz0fKMeFqRpi0"; protected-headers="v1" From: Harry Yoo To: Pengpeng Hou , "Vlastimil Babka (SUSE)" , Andrew Morton , linux-mm@kvack.org Cc: Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , David Hildenbrand , Lorenzo Stoakes , liam@infradead.org, Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Shuah Khan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <94eaac52-30a9-4607-a9e9-b2401fe7224f@kernel.org> Subject: Re: [RFC PATCH 0/5] mm/slub: preserve previous object lifetime References: <20260611063926.38111-1-pengpeng@iscas.ac.cn> <55b1b674-6487-4585-8a0d-919373e66d3a@kernel.org> <763e61e9-9270-4057-938f-daf9184a41ae@kernel.org> <20260615061202.23715-1-pengpeng@iscas.ac.cn> In-Reply-To: <20260615061202.23715-1-pengpeng@iscas.ac.cn> --------------G4FEeR7cIx4Wz0fKMeFqRpi0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 6/15/26 3:12 PM, Pengpeng Hou wrote: > Hi Vlastimil, Harry, >=20 > Thanks for the feedback. >=20 > I agree that the terminology in the RFC cover letter was not precise > enough. The case I was trying to describe is a duplicate/stale free by = a > previous owner after the object has already been freed and then reused = by > another user. In that case, the current SLAB_STORE_USER records can sho= w > the current allocation and the later bad free/check, but the previous > completed alloc/free lifetime that explains where the stale pointer cam= e > from has already been overwritten. I was confused, but I see now, thanks for clarifying :) > This is not intended to compete with KASAN or infer semantic ownership.= > KASAN is better when it can be used, but the motivation here is the low= er > barrier of enabling slub_debug for a specific cache on an existing kern= el, > especially in field debugging environments. Makes sense. > Based on your comments, I will rework the non-RFC version to fold this > into the existing U tracking instead of adding a separate H option, unl= ess > there is a preference for keeping the extra history behind an explicit > flag. Ack. > I will keep the scope to one previous completed lifetime and avoid a > larger history table/ring for now. Ack. > I will also add a small reproducer or KUnit coverage showing the lost > previous-lifetime case, Ack. > plus object-size/order comparison data for a few > representative caches. I think we don't care much about the size on debug caches. Looking forward to seeing the next version, Pengpeng. Thanks! --=20 Cheers, Harry / Hyeonggon --------------G4FEeR7cIx4Wz0fKMeFqRpi0-- --------------rQympXZWzOdztZ7GV117DY9T Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQQQ1ub6gR5ogjaKRmOGXBN6rc5S1gUCajDN2QAKCRCGXBN6rc5S 1jU9AQDY8LKVc8r2fE8Zd9WTZ2qOoM4VI5oB5t/0l+40EvXamAEAgdzv/BQewUjP PvkfhEyPtnGcfrwoSH+ssHc3E6NUvgM= =nV87 -----END PGP SIGNATURE----- --------------rQympXZWzOdztZ7GV117DY9T--