Message-ID: <4599013d-bc74-4f81-9db7-070806ea9162@gmx.com>
Date: Fri, 18 Apr 2025 20:31:23 +0930
From: Qu Wenruo <quwenruo.btrfs@....com>
To: Linux Memory Management List <linux-mm@...ck.org>,
 LKML <linux-kernel@...r.kernel.org>
Subject: Kernel 6.15-rc2 unable to boot on 32bit x86 with PAE

Hi,

Recently I'm testing a situation where highmem is involved, thus I'm 
building the latest 32bit x86 with HIGHMEM and PAE, and run it inside a 
qemu VM.

However the kernel just fails to boot with very early memory management 
crash:

[    0.064551] Built 1 zonelists, mobility grouping on.  Total pages: 786297
[    0.065269] allocated 4198396 bytes of page_ext
[    0.065856] mem auto-init: stack:off, heap alloc:on, heap free:off
[    0.070213] BUG: Bad page state in process swapper  pfn:100001
[    0.070773] page: refcount:0 mapcount:1 mapping:(ptrval) index:0x0 
pfn:0x100001
[    0.071451] aops:0x0 ino:850fc085 invalid dentry:2cc54702
[    0.071962] BUG: kernel NULL pointer dereference, address: 00000400
[    0.072609] #PF: supervisor read access in kernel mode
[    0.073135] #PF: error_code(0x0000) - not-present page
[    0.073621] *pdpt = 0000000000000000 *pde = f000ff53f000ff53
[    0.074269] Oops: Oops: 0000 [#1] SMP NOPTI
[    0.074666] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 
6.15.0-rc2-custom+ #5 PREEMPT(undef) 
a4004de2bdc11241c6afe44ab7f6bd7d8e98e3db
[    0.075828] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), 
BIOS Arch Linux 1.16.3-1-1 04/01/2014
[    0.076706] EIP: get_pfnblock_flags_mask+0x40/0x50
[    0.077160] Code: 03 00 00 8b 8e 48 14 33 d7 8b 96 44 14 33 d7 81 e1 
00 fe ff ff 29 c8 c1 e8 09 8d 0c 85 00 00 00 00 c1 e8 03 8d 04 82 83 e1 
1f <8b> 00 d3 e8 21 d8 5b 5e 5d 31 d2 31 c9 c3 66 90 e8 e3 bf d6 ff 55
[    0.078954] EAX: 00000400 EBX: 00000007 ECX: 00000000 EDX: 00000000
[    0.079567] ESI: 00000a80 EDI: d70ebce5 EBP: d71fdd80 ESP: d71fdd78
[    0.080156] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00210046
[    0.080796] CR0: 80050033 CR2: 00000400 CR3: 1749a000 CR4: 000000b0
[    0.081378] Call Trace:
[    0.081602]  __dump_page.cold+0x11d/0x23f
[    0.081977]  ? prb_read_valid+0x29/0x40
[    0.082334]  ? console_unlock+0x56/0x100
[    0.082701]  ? console_unlock+0x56/0x100
[    0.083070]  ? vprintk_emit+0x2d2/0x390
[    0.083458]  ? vprintk_default+0x15/0x20
[    0.083826]  dump_page+0x1b/0x30
[    0.084127]  ? dump_page+0x1b/0x30
[    0.084447]  bad_page.cold+0x62/0x84
[    0.084796]  free_tail_page_prepare+0x134/0x190
[    0.085232]  __free_pages_ok+0x318/0x3c0
[    0.085607]  __free_pages_core+0x4e/0x58
[    0.085982]  memblock_free_pages+0x11/0x34
[    0.086378]  memblock_free_all+0x149/0x1b4
[    0.086766]  mm_core_init+0x103/0x158
[    0.087121]  start_kernel+0x5d2/0x7f8
[    0.087462]  ? load_ucode_bsp+0x53/0xdc
[    0.087832]  i386_start_kernel+0x64/0x64
[    0.088195]  startup_32_smp+0x151/0x154
[    0.088561] Modules linked in:
[    0.088865] CR2: 0000000000000400
[    0.089185] ---[ end trace 0000000000000000 ]---
[    0.089624] EIP: get_pfnblock_flags_mask+0x40/0x50
[    0.090093] Code: 03 00 00 8b 8e 48 14 33 d7 8b 96 44 14 33 d7 81 e1 
00 fe ff ff 29 c8 c1 e8 09 8d 0c 85 00 00 00 00 c1 e8 03 8d 04 82 83 e1 
1f <8b> 00 d3 e8 21 d8 5b 5e 5d 31 d2 31 c9 c3 66 90 e8 e3 bf d6 ff 55
[    0.091910] EAX: 00000400 EBX: 00000007 ECX: 00000000 EDX: 00000000
[    0.092505] ESI: 00000a80 EDI: d70ebce5 EBP: d71fdd80 ESP: d71fdd78
[    0.093111] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00210046
[    0.093788] CR0: 80050033 CR2: 00000400 CR3: 1749a000 CR4: 000000b0
[    0.094415] Kernel panic - not syncing: Attempted to kill the idle task!
[    0.095097] ---[ end Kernel panic - not syncing: Attempted to kill 
the idle task! ]---

The full dmesg is attached (boot.txt).

The crash only happens with PAE enabled. If only HIGHMEM enabled but no 
PAE, the kernel boots without any problem.

Thanks,
Qu

View attachment "boot.txt" of type "text/plain" (10012 bytes)

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