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Thu, 16 Nov 2023 09:17:22 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DE39720040; Thu, 16 Nov 2023 09:17:21 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 97C8F20049; Thu, 16 Nov 2023 09:17:20 +0000 (GMT) Received: from [9.179.9.51] (unknown [9.179.9.51]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 16 Nov 2023 09:17:20 +0000 (GMT) Message-ID: <8fb810e5000dd66334a4a686407c0caeacb79f55.camel@linux.ibm.com> Subject: Re: [PATCH 12/32] kmsan: Allow disabling KMSAN checks for the current task From: Ilya Leoshkevich To: Alexander Potapenko Cc: Alexander Gordeev , Andrew Morton , Christoph Lameter , David Rientjes , Joonsoo Kim , Marco Elver , Masami Hiramatsu , Pekka Enberg , Steven Rostedt , Vasily Gorbik , Vlastimil Babka , Christian Borntraeger , Dmitry Vyukov , Hyeonggon Yoo <42.hyeyoo@gmail.com>, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Mark Rutland , Roman Gushchin , Sven Schnelle Date: Thu, 16 Nov 2023 10:17:20 +0100 In-Reply-To: References: <20231115203401.2495875-1-iii@linux.ibm.com> <20231115203401.2495875-13-iii@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.48.4 (3.48.4-1.fc38) MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: vSTD9xF44d83VprYex3tMD-37iq0_k9g X-Proofpoint-GUID: oH4OOC-OhoTloo5LiN9lT2emIfEOQ-qd X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.987,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-11-16_07,2023-11-15_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 mlxlogscore=999 malwarescore=0 suspectscore=0 adultscore=0 priorityscore=1501 mlxscore=0 bulkscore=0 phishscore=0 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311060000 definitions=main-2311160074 X-Rspamd-Queue-Id: DA06D80003 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: u9tpawk1tdf4fbfh3siu86k7o89id9bi X-HE-Tag: 1700126259-218561 X-HE-Meta: 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 IP1EUcEi Xv+SSD74RKKlFZMZjbHrGDGQPFkloeH1ez19JMT3Bn76Sr1IGjRKD1mF3GEFRwU7P9VmqabTfAs6j8o0zQ1wKwA2RtiR1gYHUJ9pK8rFJn/JuC7i/yuQxsPQuBVrxoGZEvNZvKopZPvnpTeJGHXv07A57HSlBWljdj8usr3Gq9onXLGCvgr60OrTUd3+Vo3Q6YUmLQ/3NM1iKy+jaSXpcQxwO/GK+0uf972fQjnHqJtCXHJQZBIYsFwxNleTkKU/OjAItGHsmTfbZNbtdXeiJant4FgI2Ja2ulncZ/Mc74oT1zYM332sS5lI5/WlMQ3gyAdA6DCi1kWvAeQANQvS59juFDQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000008, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 2023-11-16 at 09:56 +0100, Alexander Potapenko wrote: > On Wed, Nov 15, 2023 at 9:34=E2=80=AFPM Ilya Leoshkevich > wrote: > >=20 > > Like for KASAN, it's useful to temporarily disable KMSAN checks > > around, > > e.g., redzone accesses. >=20 > This example is incorrect, because KMSAN does not have redzones. > You are calling these functions from "mm: slub: Let KMSAN access > metadata", which mentiones redzones in kfree(), but the description > is > still somewhat unclear. > Can you provide more insight about what is going on? Maybe we can fix > those accesses instead of disabling KMSAN? It's about SLUB redzones, which appear when compiling with CONFIG_DEBUG_SLAB. I think that from KMSAN's point of view they should be considered poisoned, but then the question is what to do with functions that check them. I noticed that there was special handling for KASAN there already, so I figured that the best solution would be to do the same thing for KMSAN.