is it some issue about HIGHMEM for mips32?

Quoted 5 lines · Figo.zhang

hi,
i am using 24KC soc, and linux2.6.21.5 kernel and set CONFIG_HIGHMEM enable. if my realy physic RAM is not more than HIGHMEM, such as only 32MB, it is some issue about kernel, i dont know how to fix it? I try linux-2.6.31.4, it is no this issue, is it some change , how to fix it?

Hello, here is the unique commit about the higmem I can found:

commit bb86bf28aec6d0a207ae09f38a43e94133d4d6db

Author: Ralf Baechle <[email protected]>
Date:   Sat Apr 25 11:25:34 2009 +0200

MIPS: Fix highmem.

Commit 351336929ccf222ae38ff0cb7a8dd5fd5c6236a0 (kernel.org) rsp. b3594a089f1c17ff919f8f78505c3f20e1f6f8ce (linux-mips.org):

> From: Chris Dearman <[email protected]>
> Date: Wed, 19 Sep 2007 00:58:24 +0100
> Subject: [PATCH] [MIPS] Allow setting of the cache attribute at
run time.

Quoted 2 lines

Slightly tacky, but there is a precedent in the sparc archirecture

code.

introduces the variable _page_cachable_default, which defaults to
zero and.
is used to create the prototype PTE for __kmap_atomic in arch/mips/mm/init.c:kmap_init before initialization in arch/mips/mm/c-r4k.c:coherency_setup, so the default value of 0 will
be
used as the CCA of kmap atomic pages which on many processors is not
a
defined CCA value and may result in writes to kmap_atomic pages
getting
corrupted. Debugged by Jon Fraser ([email protected]).

Could you please try to apply it, and test it again?

Quoted 97 lines

here is my kernel log:
Linux version 2.6.21.5 (figo@myhost) (gcc version 4.1.2) #22 Fri Dec 4 10:33:25 CST 2009
CPU revision is: 00019655
Determined physical RAM map:
memory: start:0x0,size=0x2000000,type=0x1
(usable)
User-defined physical RAM map:
memory: start:0x0,size=0x2000000,type=0x1
(usable)
Initrd not found or empty - disabling initrd
Built 1 zonelists. Total pages: 8128
Kernel command line: console=ttyS0,115200 rdinit=/linuxrc mem=32M nofpu mac=00:aa:aa:bb:bb:99
Updated MAC address from u-boot: 8024ff24M
Primary instruction cache 32kB, physically tagged, 4-way, linesize 32 bytes.
Primary data cache 32kB, 4-way, linesize 32 bytes. Synthesized TLB refill handler (20 instructions). Synthesized TLB load handler fastpath (32 instructions). Synthesized TLB store handler fastpath (32 instructions). Synthesized TLB modify handler fastpath (31 instructions). Cache parity protection disabled arch/mips/mach-opulan/optrann/irq.c,arch_init_irq
PID hash table entries: 128 (order: 7, 512 bytes)
Using 150.000 MHz high precision timer. arch/mips/mach-opulan/optrann/time.c,plat_timer_setup
Dentry cache hash table entries: 4096 (order: 2, 16384 bytes) Inode-cache hash table entries: 2048 (order: 1, 8192 bytes)
Memory: 29012k/32768k available (1798k kernel code, 3756k reserved, 369k data, 900k init, 0k highmem)
Mount-cache hash table entries: 512
NET: Registered protocol family 16
Generic PHY: Registered new driver
Time: MIPS clocksource has been installed.
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes) TCP established hash table entries: 1024 (order: 1, 8192 bytes) TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
TCP: Hash tables configured (established 1024 bind 1024)
TCP reno registered
Installing knfsd (copyright (C) 1996 [email protected]).
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
Serial: optrann serial driver $Revision: 1.0 uart_register_driver finished
ttyS0 at MMIO map 0xbf004000 mem 0xbf004000 (irq = 23) is a UART 0 RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
loop: loaded (max 8 devices)
nbd: registered device at major 43
optrann_fe_ether Ethernet driver, V1.00
FE:dmac_regs =0xbf014000,msg_regs=0xbf028000, irq=26
FE MAC: 00:aa:aa:bb:bb:99
TCP cubic registered
Freeing unused kernel memory: 900k freed ramdisk_execute_command=/linuxrc, execute_command=<NULL>
Bad pte = 0135c79f, process = linuxrc, vm_flags = 100073, vaddr = 2aaae000

Call Trace:
[<80048d70>] dump_stack+0x8/0x34
[<8009ebb0>] vm_normal_page+0x68/0x90
[<8009f850>] unmap_vmas+0x1e8/0x5e8
[<800a3428>] unmap_region+0x9c/0x184
[<800a4268>] do_munmap+0x1b0/0x25c
[<800a4358>] sys_munmap+0x44/0x70
[<8004af40>] stack_done+0x20/0x3c
Bad pte = 0135e79f, process = linuxrc, vm_flags = 100073, vaddr =
2aaae000
Call Trace:
[<80048d70>] dump_stack+0x8/0x34
[<8009ebb0>] vm_normal_page+0x68/0x90
[<8009f850>] unmap_vmas+0x1e8/0x5e8
[<800a3428>] unmap_region+0x9c/0x184
[<800a4268>] do_munmap+0x1b0/0x25c
[<800a4358>] sys_munmap+0x44/0x70
[<8004af40>] stack_done+0x20/0x3c
Bad pte = 0026079f, process = linuxrc, vm_flags = 100073, vaddr =
2aaae000
Call Trace:
[<80048d70>] dump_stack+0x8/0x34
[<8009ebb0>] vm_normal_page+0x68/0x90
[<8009f850>] unmap_vmas+0x1e8/0x5e8
[<800a3428>] unmap_region+0x9c/0x184
[<800a4268>] do_munmap+0x1b0/0x25c
[<800a4358>] sys_munmap+0x44/0x70
[<8004af40>] stack_done+0x20/0x3c

.........

Best,
Figo.zhang