Hello again,
this problem is reproducable with 2.4.20 kernel ...
with mem=800M, ioremap returns NULL for some high adresses.
and with mem=950M, I got the following "trap"
Jan 28 18:47:31 forceps kernel: mem1[mem1_module_init]: loading driver (dmask: 0x0)
Jan 28 18:47:31 forceps kernel: kernel BUG at page_alloc.c:102!
Jan 28 18:47:31 forceps kernel: invalid operand: 0000
Jan 28 18:47:31 forceps kernel: CPU: 0
Jan 28 18:47:31 forceps kernel: EIP: 0010:[__free_pages_ok+84/744] Not tainted
Jan 28 18:47:31 forceps kernel: EFLAGS: 00010282
Jan 28 18:47:31 forceps kernel: eax: c1ae1000 ebx: c1a81280 ecx: c1a8129c edx: c1ad8a00
Jan 28 18:47:31 forceps kernel: esi: 00000000 edi: f7e4931c ebp: f6e8fe74 esp: f6e8fe40
Jan 28 18:47:31 forceps kernel: ds: 0018 es: 0018 ss: 0018
Jan 28 18:47:31 forceps kernel: Process insmod (pid: 1247, stackpage=f6e8f000)
Jan 28 18:47:31 forceps kernel: Stack: 000c7000 000c8000 f7e4931c 00000001 00000001 f6e8fe70 c\
0112610 c01125b0
Jan 28 18:47:31 forceps kernel: 00000000 00000001 00000001 00400000 f6e8feb0 f6e8fe7c c\
0137617 f6e8fea8
Jan 28 18:47:31 forceps kernel: c01324f8 f55eadac f88c6000 00062000 f8cc6000 c0101f8c c\
0101f8c 004c6000
Jan 28 18:47:31 forceps kernel: Call Trace: [flush_tlb_all+20/96] [flush_tlb_all_ipi+0/76] \
[__free_pages+31/36] [vmfree_area_pages+296/380] [vfree+57/180]
Jan 28 18:47:31 forceps kernel: [<f88c4063>] [iounmap+25/29] [<f88c430d>] [<f88c48f3>] [<f88\
c48f3>] [<f88c4065>]
Jan 28 18:47:31 forceps kernel: [<f88c43c8>] [<f88c407e>] [<f88c4540>] [<f88c4065>] [free_pa\
ges+32/36] [sys_init_module+1363/1596]
Jan 28 18:47:31 forceps kernel: [<f88c4060>] [system_call+51/56]
Jan 28 18:47:31 forceps kernel:
Jan 28 18:47:31 forceps kernel: Code: 0f 0b 66 00 83 5c 29 c0 89 d8 2b 05 10 6b 38 c0 69 c0 ab\
aa
Is there any documentation on how the high memory above the one reserved by mem=800M is handled ? Why ioremap
returns non NULL if I do ioremap/iounmap for each pages from 800M to 1GB and then returns NULL after some ioremapping
pages (without unmapping) from 800M to some size ?
Thanks in advance.
David Geldreich wrote:
>
> [1.] ioremap returning NULL and non-NULL for the same high memory adresses
>
> [2.] some drivers uses high memory limiting the kernel usage with
> mem=800M and using the above memory. With a kernel compiled with
> CONFIG_HIGHMEM4G=y, ioremap returns NULL for some high memory
> adress where it returned a non-NULL value for the same high memory adress.
>
> To test the available memory, the driver starts at high-memory and
> probes each page (ioremap it, write into it, read the written value,
> iounmap it). When the read value != from the written value it assumes
> that it is the end of the physical memory.
>
> After the driver try to ioremap buffers in this high memory, for the
> first buffers ioremap returns right values but after some calls it
> returns 0x00000. In the case of mem=800M, it stops around 180M (430
> buffers of 442368 bytes) instead of the 224M free reported by the
> available memory test.
>
> [3.] keywords: kernel, memory, ioremap
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This archive was generated by hypermail 2b29 : Fri Jan 31 2003 - 22:00:20 EST