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Wed, 2 Sep 2026 06:21:19 +0000 (GMT) Message-ID: <42267839-e344-474b-a91c-efd337808f98@linux.ibm.com> Date: Wed, 2 Sep 2026 11:51:18 +0530 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 v5 1/2] x86/crash: reserve elfcorehdr for CONFIG_NR_CPUS, not CONFIG_NR_CPUS_DEFAULT To: "Ionut Nechita (Wind River)" , x86@kernel.org, kexec@lists.infradead.org Cc: tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, akpm@linux-foundation.org, baoquan.he@linux.dev, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, ruirui.yang@linux.dev, eric.devolder@oracle.com, hbathini@linux.ibm.com, ruanjinjie@huawei.com, brads@mainlining.org, linux-kernel@vger.kernel.org References: <20260901071041.16311-1-ionut.nechita@windriver.com> <20260901071041.16311-2-ionut.nechita@windriver.com> Content-Language: en-US From: Sourabh Jain In-Reply-To: <20260901071041.16311-2-ionut.nechita@windriver.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=bc1bluPB c=1 sm=1 tr=0 ts=6a97c066 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=i0EeH86SAAAA:8 a=t7CeM3EgAAAA:8 a=OuZLqq7tAAAA:8 a=VnNF1IyMAAAA:8 a=L4ZZY0jnB1IY1FPthvAA:9 a=QEXdDO2ut3YA:10 a=FdTzh2GWekK77mhwV6Dw:22 a=AKGiAy9iJ-JzxKVHQNES:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTAyMDA1MiBTYWx0ZWRfX3X4Yx0mx/ZQY svzdWJWj2+tYN+QPzzIIF/OLS3/SeP8hh2ROQ78D5C1GWV/zFos0IEJyERpw04JQE1Fa4HdcXP6 Qy9ByIsErqmUWBDTms4SFlh3W9d3SVU= X-Proofpoint-ORIG-GUID: sKHmp-1hy7wmST2jZ1nqH9q5Sb9NhB6v X-Proofpoint-GUID: sKHmp-1hy7wmST2jZ1nqH9q5Sb9NhB6v X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTAyMDA1MiBTYWx0ZWRfX5GIXSHld/bRT co7e8vjZfljKlPhxPmoNG5rvpBVFI+bmVyRUHAjKwJrUm5569/jHEUAd8nTkt88YpLvOsS7oGCZ NwtUFvCVTSodu/a13oM5N9Ihy5MZBaD0JForwkdntI54f0lzmckegk6+P//5RsLosqcuj2TF5tv 2//9GzbgEl9EEqpjMk71wvujIXK0GY5tb3fG09Z3t+uCwUPj036VUYgh3QSLLfsdfAJFlGxGOh0 GkCLfLxy8mkFQt2ZcPG45+aCpoOlKXxW6cL6BEvngChQF197X9AkqjS8AQu2LXZz2Wrl9lCHqTh FJExS/NdyewygazJg9sdX0houOXz3XXSFNL0B1HHsY0VLGaPV03Hpp6+Rmt79tAK7Se3/OrL+sv uUWZ6intZIx+SALyVgdYUihQ8y8CRXaLrDJ5cj+PbZBRIwnXRu3alRDPUWDcYm6z5x/GXl/bgxj m3YYMoi8971KfB+P5+w== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-01_06,2026-09-01_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 suspectscore=0 adultscore=0 malwarescore=0 spamscore=0 lowpriorityscore=0 phishscore=0 clxscore=1011 priorityscore=1501 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609020052 Hello, The below patch overrides the changes introduce here: https://lore.kernel.org/all/20260826092541.3905933-13-ruanjinjie@huawei.com/ Can you please review the above patch instead? - Sourabh Jain On 01/09/26 12:40, Ionut Nechita (Wind River) wrote: > From: Ionut Nechita > > NR_CPUS_DEFAULT is purely a Kconfig thing. Its entire purpose in life is > to start NR_CPUS at a sane value. There is precisely one (buggy) > reference to it outside of Kconfig in the whole kernel: the x86 crash > code. > > That code undersizes the elfcorehdr reservation whenever NR_CPUS exceeds > NR_CPUS_DEFAULT, because the header carries one phdr per possible CPU and > num_possible_cpus() is bounded by NR_CPUS. kexec_file_load(2) then fails > with -EINVAL from sanity_check_segment_list(), and kexec_load(2) silently > truncates the elfcorehdr, which surfaces later as a bad or unusable dump. > > Size the elfcorehdr reservation with NR_CPUS instead. > > Fixes: ea53ad9cf73b ("x86/crash: add x86 crash hotplug support") > Assisted-by: LLM > Signed-off-by: Ionut Nechita > Reviewed-by: Jinjie Ruan > Reviewed-by: Bradley Morgan > Reviewed-by: Sourabh Jain > Acked-by: Baoquan He > --- > arch/x86/kernel/crash.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > index e681ec9cf1dc..e6f23933a6df 100644 > --- a/arch/x86/kernel/crash.c > +++ b/arch/x86/kernel/crash.c > @@ -369,9 +369,9 @@ int crash_load_segments(struct kimage *image) > * maximum CPUs and maximum memory ranges. > */ > if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) > - pnum = 2 + CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES; > + pnum = 2 + CONFIG_NR_CPUS + CONFIG_CRASH_MAX_MEMORY_RANGES; > else > - pnum += 2 + CONFIG_NR_CPUS_DEFAULT; > + pnum += 2 + CONFIG_NR_CPUS; > > if (pnum < (unsigned long)PN_XNUM) { > kbuf.memsz = pnum * sizeof(Elf64_Phdr); > @@ -430,7 +430,7 @@ unsigned int arch_crash_get_elfcorehdr_size(void) > unsigned int sz; > > /* kernel_map, VMCOREINFO and maximum CPUs */ > - sz = 2 + CONFIG_NR_CPUS_DEFAULT; > + sz = 2 + CONFIG_NR_CPUS; > if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) > sz += CONFIG_CRASH_MAX_MEMORY_RANGES; > sz *= sizeof(Elf64_Phdr); > > base-commit: 89c07d98716a13454ec3fd9f97689e812cc71bd4