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Fri, 10 Oct 2025 02:34:02 -0700 (PDT) Date: Fri, 10 Oct 2025 02:33:59 -0700 From: Breno Leitao To: Changyuan Lyu , rppt@kernel.org Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, anthony.yznaga@oracle.com, arnd@arndb.de, ashish.kalra@amd.com, benh@kernel.crashing.org, bp@alien8.de, catalin.marinas@arm.com, corbet@lwn.net, dave.hansen@linux.intel.com, devicetree@vger.kernel.org, dwmw2@infradead.org, ebiederm@xmission.com, graf@amazon.com, hpa@zytor.com, jgowans@amazon.com, kexec@lists.infradead.org, krzk@kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, luto@kernel.org, mark.rutland@arm.com, mingo@redhat.com, pasha.tatashin@soleen.com, pbonzini@redhat.com, peterz@infradead.org, ptyadav@amazon.de, robh@kernel.org, rostedt@goodmis.org, rppt@kernel.org, saravanak@google.com, skinsburskii@linux.microsoft.com, tglx@linutronix.de, thomas.lendacky@amd.com, will@kernel.org, x86@kernel.org Subject: Re: [PATCH v8 01/17] memblock: add MEMBLOCK_RSRV_KERN flag Message-ID: References: <20250509074635.3187114-1-changyuanl@google.com> <20250509074635.3187114-2-changyuanl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250509074635.3187114-2-changyuanl@google.com> X-Rspamd-Server: rspam05 X-Stat-Signature: 7ny7gefw7rsb67omnm4z5fqp5fy5uwoy X-Rspam-User: X-Rspamd-Queue-Id: 2747310000E X-HE-Tag: 1760088844-993913 X-HE-Meta: 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 xDbHn0ir 6E7x/z4sgfTlmvxGy1a/h9rphr5YJ94GxAMjPjHXt6+nR8Y/19HhUqXGCCftaoBz6h+yoc3G5y3azr09QIF+TbeHwdpZD/IXnOe5AXNzgmE93upeZ+YcPpWOFh7TkjrwhSgCnBQQRrzrPQyBl0pwTzqEArpQmujgEtPJ2dutztYT+iNNRCbBQuGc1kJr7N0B1uovPu1kguJsXPj6w4qLEnLTcH1SN8QFtXaY/JwKia71lhcXjWDT15bNR0nhj5ifdxigOpbG5IMe/R9wdPJRCwdzaUBO5g7nxih0hcHRw1lgMrmB4Yx+rnFz+jfptTkdlWqK1BF5DI+Opx9IvBkrVZKfpQfA3YJm5owe5fMwly41e3jYnB3rBHSNyVweDuliZIvu4m6usWzuu5chcsgce/xBmNHjNqyrjbdQoV6heDpriK3+5kWNS1sav16tWOoQL1UsZXIl6VornXBw= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello Chanyuan, Mike, On Fri, May 09, 2025 at 12:46:19AM -0700, Changyuan Lyu wrote: > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -492,7 +492,7 @@ static int __init_memblock memblock_double_array(struct memblock_type *type, > * needn't do it > */ > if (!use_slab) > - BUG_ON(memblock_reserve(addr, new_alloc_size)); > + BUG_ON(memblock_reserve_kern(addr, new_alloc_size)); > > /* Update slab flag */ > *in_slab = use_slab; > @@ -642,7 +642,7 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, > #ifdef CONFIG_NUMA > WARN_ON(nid != memblock_get_region_node(rgn)); > #endif > - WARN_ON(flags != rgn->flags); > + WARN_ON(flags != MEMBLOCK_NONE && flags != rgn->flags); I am hitting some sporadic warnings at early boot on a production kernel (6.16). Unfortunately this issue is not easily reproduce for me to test on upstream. 09:14:44 BIOS-provided physical RAM map: 09:14:44 BIOS-e820: [mem 0x0000000000000000-0x000000000009ffff] usable 09:14:44 BIOS-e820: [mem 0x00000000000a0000-0x00000000000fffff] reserved 09:14:44 BIOS-e820: [mem 0x0000000000100000-0x0000000064cb7fff] usable 09:14:44 BIOS-e820: [mem 0x0000000064cb8000-0x0000000064dc3fff] reserved 09:14:44 BIOS-e820: [mem 0x0000000064dc4000-0x0000000065b13fff] usable 09:14:44 BIOS-e820: [mem 0x0000000065b14000-0x0000000065b61fff] reserved 09:14:44 BIOS-e820: [mem 0x0000000065b62000-0x0000000065ed0fff] usable 09:14:44 BIOS-e820: [mem 0x0000000065ed1000-0x0000000065f2bfff] reserved 09:14:44 BIOS-e820: [mem 0x0000000065f2c000-0x0000000066621fff] usable 09:14:44 BIOS-e820: [mem 0x0000000066622000-0x0000000066630fff] reserved 09:14:44 BIOS-e820: [mem 0x0000000066631000-0x0000000068107fff] usable 09:14:44 BIOS-e820: [mem 0x0000000068108000-0x000000006819dfff] ACPI data 09:14:44 BIOS-e820: [mem 0x000000006819e000-0x000000006a48cfff] usable 09:14:44 BIOS-e820: [mem 0x000000006a48d000-0x000000006c58cfff] reserved 09:14:44 BIOS-e820: [mem 0x000000006c58d000-0x000000006c5dcfff] ACPI data 09:14:44 BIOS-e820: [mem 0x000000006c5dd000-0x000000006cfdcfff] ACPI NVS 09:14:44 BIOS-e820: [mem 0x000000006cfdd000-0x000000006e9fcfff] reserved 09:14:44 BIOS-e820: [mem 0x000000006e9fd000-0x000000006fffffff] usable 09:14:44 BIOS-e820: [mem 0x0000000070000000-0x000000008fffffff] reserved 09:14:44 BIOS-e820: [mem 0x00000000fd000000-0x00000000fe7fffff] reserved 09:14:44 BIOS-e820: [mem 0x00000000fed20000-0x00000000fed44fff] reserved 09:14:44 BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] reserved 09:14:44 BIOS-e820: [mem 0x0000000100000000-0x000000107fff655f] usable 09:14:44 BIOS-e820: [mem 0x000000107fff6560-0x000000107fff656f] type 128 09:14:44 BIOS-e820: [mem 0x000000107fff6570-0x000000107fffffff] usable 09:14:44 random: crng init done 09:14:44 ------------[ cut here ]------------ 09:14:44 WARNING: CPU: 0 PID: 0 at mm/memblock.c:668 memblock_add_range (mm/memblock.c:668) 09:14:44 Modules linked in: 09:14:44 Tainted: [S]=CPU_OUT_OF_SPEC 09:14:44 RIP: 0010:memblock_add_range (mm/memblock.c:668) 09:14:44 Code: 28 80 3c 01 00 0f 84 04 fd ff ff 4c 89 ef e8 6c 77 09 00 e9 f7 fc ff ff 0f 0b 83 7c 24 1c 00 0f 85 9c fd ff ff e9 c5 fd ff ff <0f> 0b e9 be fd ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 6b fd All code ======== 0: 28 80 3c 01 00 0f sub %al,0xf00013c(%rax) 6: 84 04 fd ff ff 4c 89 test %al,-0x76b30001(,%rdi,8) d: ef out %eax,(%dx) e: e8 6c 77 09 00 call 0x9777f 13: e9 f7 fc ff ff jmp 0xfffffffffffffd0f 18: 0f 0b ud2 1a: 83 7c 24 1c 00 cmpl $0x0,0x1c(%rsp) 1f: 0f 85 9c fd ff ff jne 0xfffffffffffffdc1 25: e9 c5 fd ff ff jmp 0xfffffffffffffdef 2a:* 0f 0b ud2 <-- trapping instruction 2c: e9 be fd ff ff jmp 0xfffffffffffffdef 31: 44 89 f1 mov %r14d,%ecx 34: 80 e1 07 and $0x7,%cl 37: 80 c1 03 add $0x3,%cl 3a: 38 c1 cmp %al,%cl 3c: 0f .byte 0xf 3d: 8c 6b fd mov %gs,-0x3(%rbx) Code starting with the faulting instruction =========================================== 0: 0f 0b ud2 2: e9 be fd ff ff jmp 0xfffffffffffffdc5 7: 44 89 f1 mov %r14d,%ecx a: 80 e1 07 and $0x7,%cl d: 80 c1 03 add $0x3,%cl 10: 38 c1 cmp %al,%cl 12: 0f .byte 0xf 13: 8c 6b fd mov %gs,-0x3(%rbx) 09:14:44 RSP: 0000:ffffffff85e07d48 EFLAGS: 00010083 ORIG_RAX: 0000000000000000 09:14:44 RAX: 0000000000000020 RBX: 0000000000001c00 RCX: dffffc0000000000 09:14:44 RDX: 000000000009f000 RSI: 000000000009d000 RDI: ffffffff8685ebf8 09:14:44 RBP: 0000000000000002 R08: 0000000000000020 R09: 0000000000000000 09:14:44 R10: ffffffffff200570 R11: fffffbffffe400b2 R12: 000000000009d000 09:14:44 R13: 0000000000100000 R14: ffffffff8edf5ce4 R15: ffffffff8edf5ce0 09:14:44 FS: 0000000000000000(0000) GS:0000000000000000(0000) knlGS:0000000000000000 09:14:44 CR2: ffff888059e2dff8 CR3: 000000005bc1d000 CR4: 00000000000000b0 09:14:44 Call Trace: 09:14:44 09:14:44 ? __memblock_reserve (mm/memblock.c:936) 09:14:44 ? add_early_ima_buffer (arch/x86/kernel/setup.c:413) 09:14:44 ? parse_setup_data (arch/x86/kernel/setup.c:500) 09:14:44 ? setup_arch (arch/x86/kernel/setup.c:245 arch/x86/kernel/setup.c:958) 09:14:44 ? start_kernel (init/main.c:922) 09:14:44 ? x86_64_start_reservations (arch/x86/kernel/ebda.c:57) 09:14:44 ? x86_64_start_kernel (arch/x86/kernel/head64.c:231) 09:14:44 ? common_startup_64 (arch/x86/kernel/head_64.S:419) 09:14:44 .... Memory: 49640988K/66772816K available (54946K kernel code, 19058K rwdata, 22636K rodata, 2940K init, 120968K bss, 10650188K reserved, 6291456K cma-reserved) So, there is a memory override, and I am curious about it. Do you think it would be useful to expand this warning to dump more information about the issue? (only compiled tested) if (flags != MEMBLOCK_NONE && flags != rgn->flags) { pr_warn("memblock: Flag mismatch at region [%pa-%pa]\n", &rgn->base, &rend); pr_warn(" Existing region flags: %#x\n", rgn->flags); pr_warn(" New range flags: %#x\n", flags); pr_warn(" New range: [%pa-%pa]\n", &base, &end); WARN_ON_ONCE(1); } Thanks --breno