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Thu, 4 Jan 2024 11:34:14 +0000 (GMT) Date: Thu, 4 Jan 2024 12:34:12 +0100 From: Heiko Carstens To: Alexander Gordeev Cc: Ilya Leoshkevich , Alexander Potapenko , 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 Subject: Re: [PATCH v3 28/34] s390/mm: Define KMSAN metadata for vmalloc and modules Message-ID: <20240104113412.7040-A-hca@linux.ibm.com> References: <20231213233605.661251-1-iii@linux.ibm.com> <20231213233605.661251-29-iii@linux.ibm.com> <20240102150531.6306-F-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-GUID: A-r5ni_NxO1svHGVXf-nj62fil3Gwpze X-Proofpoint-ORIG-GUID: OVn0-Bn5itLqAoOpBhaSOLkGr5KeaBNy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-01-04_07,2024-01-03_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 clxscore=1015 impostorscore=0 bulkscore=0 mlxscore=0 mlxlogscore=678 malwarescore=0 spamscore=0 priorityscore=1501 adultscore=0 phishscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2401040088 On Thu, Jan 04, 2024 at 11:03:42AM +0100, Alexander Gordeev wrote: > On Tue, Jan 02, 2024 at 04:05:31PM +0100, Heiko Carstens wrote: > Hi Heiko, > ... > > > @@ -253,9 +253,17 @@ static unsigned long setup_kernel_memory_layout(void) > > > MODULES_END = round_down(__abs_lowcore, _SEGMENT_SIZE); > > > MODULES_VADDR = MODULES_END - MODULES_LEN; > > > VMALLOC_END = MODULES_VADDR; > > > +#ifdef CONFIG_KMSAN > > > + VMALLOC_END -= MODULES_LEN * 2; > > > +#endif > > > > > > /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */ > > > vmalloc_size = min(vmalloc_size, round_down(VMALLOC_END / 2, _REGION3_SIZE)); > > > +#ifdef CONFIG_KMSAN > > > + /* take 2/3 of vmalloc area for KMSAN shadow and origins */ > > > + vmalloc_size = round_down(vmalloc_size / 3, _REGION3_SIZE); > > > + VMALLOC_END -= vmalloc_size * 2; > > > +#endif > > > > Please use > > > > if (IS_ENABLED(CONFIG_KMSAN)) > > > > above, since this way we get more compile time checks. > > This way we will get a mixture of CONFIG_KASAN and CONFIG_KMSAN > #ifdef vs IS_ENABLED() checks within one function. I guess, we > would rather address it with a separate cleanup? I don't think so, since you can't convert the CONFIG_KASAN ifdef to IS_ENABLED() here: it won't compile. But IS_ENABLED(CONFIG_KMSAN) should work. I highly prefer IS_ENABLED() over ifdef since it allows for better compile time checks, and you won't be surprised by code that doesn't compile if you just change a config option. We've seen that way too often.