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Thu, 8 May 2025 03:24:53 -0500 Received: from webmail.sarc.samsung.com ([172.30.39.9]) by ATXPVPPTAGT04.sarc.samsung.com (PPS) with ESMTP id 46df5w3mty-1; Thu, 08 May 2025 03:24:53 -0500 Received: from sarc.samsung.com (105.148.145.5) by au1ppexchange01.sarc.samsung.com (105.148.32.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.4; Thu, 8 May 2025 03:24:51 -0500 Date: Thu, 8 May 2025 11:24:43 +0300 From: Pantelis Antoniou To: Andrew Morton CC: , , Artem Krupotkin , Charles Briere , "Wade Farnsworth" Subject: Re: [PATCH 0/1] Fix zero copy I/O on __get_user_pages allocated pages Message-ID: <20250508112443.49ff0414@sarc.samsung.com> In-Reply-To: <20250507145018.385c0a090a0d61c06e985ad9@linux-foundation.org> Organization: SARC X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; 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 X-ClientProxiedBy: au1ppexchange04.sarc.samsung.com (105.148.32.84) To au1ppexchange01.sarc.samsung.com (105.148.32.81) X-CFilter-Loop: Reflected Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Proofpoint-GUID: 4PeEZ1aymWH1pEADgeqC-xh1MxcKHdE7 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNTA4MDA3MyBTYWx0ZWRfXwC7v/t1idwe7 xe0rUmgQIin4dSxD3sdt8qMjeej6uOx7+D84agRnXQeM4q13fSM2DeCbzgjnY7hsvn1w7uKvgyP mWNyrwpMH8GJiKdbveBHTQyePuQ5a8kVc2adKAPmafRneMhtz3kZx66UcayTujKVFaeMiGdizFg 1YcMNpXJgwz38+OVbA1DDtI180Cr/Tf1LmfzkNVZ+CvRrJ/FGpin8fO+PwQC7ClBCdwSKHYIOFT O7Mn39zhBbauGyFdKLhRWQwbjcdf9srM2ReYgtg7+87kATYEMDBJK8OZz9T/vpjVY7Ioufzoesj VTd8XfUS/UdJLA/A8iOWgyPoGbqJqbdotgoZLwAa4oVu0dEpndd6AuI/uZTrIG7U2FpGFeoXH9w qtcMf2/5 X-Proofpoint-ORIG-GUID: 4PeEZ1aymWH1pEADgeqC-xh1MxcKHdE7 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-05-08_02,2025-05-07_02,2025-02-21_01 X-Proofpoint-Spam-Details: rule=outbound_spam_notspam policy=outbound_spam score=0 spamscore=0 adultscore=0 mlxscore=0 malwarescore=0 bulkscore=0 priorityscore=1501 impostorscore=0 suspectscore=0 mlxlogscore=809 lowpriorityscore=0 phishscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2504070000 definitions=main-2505080073 X-CMS-MailID: 20250508082454uscas1p29b50ff4d2f31a53e732cebf11535a549 X-CMS-RootMailID: 20250507154119uscas1p2a4055d14ab111fdb94a6378789c38d9d References: <20250507154105.763088-1-p.antoniou@partner.samsung.com> <20250507145018.385c0a090a0d61c06e985ad9@linux-foundation.org> On Wed, 7 May 2025 14:50:18 -0700 Andrew Morton wrote: > On Wed, 7 May 2025 10:=E2=80=8A41:=E2=80=8A04 -0500 Pantelis Antoniou partner.=E2=80=8Asamsung.=E2=80=8Acom> wrote: > Updates to network filesy= stems > enabled zero copy I/O by using the > netfslib common accessors. > Updates by whom? Are all the people who=20 > On Wed, 7 May 2025 10:41:04 -0500 Pantelis Antoniou > wrote: >=20 > > Updates to network filesystems enabled zero copy I/O by using the > > netfslib common accessors. >=20 > Updates by whom? Are all the people who need to know about this being > cc'ed here? >=20 I think the first cover letter contains that information. > > One example of that is the 9p filesystem which is commonly used in > > qemu based setups for sharing files with the host. > >=20 > > In our emulation environment we have noticed failing writes when > > performing I/O from a userspace mapped DRM GEM buffer object. > > The platform does not use VRAM, all graphics memory is regular DRAM > > memory, allocated via __get_free_pages >=20 > We should identify which kernel version(s) should be patched, please.=20 > 6.16-rc1? 6.15? -stable? >=20 The first occurance of the bug was on internal kernel tree that was based on 6.8. This patch is against 6.15-rc5. > I often make these decisions but in this case I have far too little > information to be able to do that. >=20 No worries. I see that this is picked up for mm unstable as is? Do you want me to generate a single patch merging the info of the cover letter and the single patch? The reason for the split is that I was not sure if you needed to have all the sordid details included in the applied patch. FWIW, we also have a buildroot patch that exhibits the problem in a much simplified way that what the original bug report came about. I don't think its appropriate content for the list, but I can share if anyone is curious about it. > Thanks. Regards -- Pantelis