On 28.04.2011 17:51, Stefan Assmann wrote:
> On 04/28/2011 05:08 PM, Andi Kleen wrote:
>>> You're right, logging every page marked would be too verbose. That's why
>>> I wrapped that logging into pr_debug.
>>
>> pr_debug still floods the kernel log buffer. On large systems
>> it often already overflows.
>
> That's a pain then, I understand.
I took a closer look at pr_debug and it seems that pr_debug gets
evaluated to a conditional branch and thus does not flood the log buffer
if not explicitly enabled. I confirmed that by dumping the log buffer.
So in the normal use-case things should be fine and if pr_debug really
is enabled it dumps a lot of data, which I hope is acceptable for
debugging purposes.
>
>>
>>> However I kept the printk in the case of early allocated pages. The user
>>> should be notified of the attempt to mark a page that's already been
>>> allocated by the kernel itself.
>>
>> That's ok, although if you're unlucky (e.g. hit a large mem_map area)
>> it can be also very nosiy.
>>
>> It would be better if you fixed the printks to output ranges.
>
> BadRAM patterns might often mark non-consecutive pages so outputting
> ranges could be more verbose than what we have now. I'll try to think
> of something to minimize log output.
How about the following:
static int __init badram_mark_pages(unsigned long addr, unsigned long mask)
{
unsigned long pagecount = 0, is_reserved = 0;
[...]
printk(KERN_INFO "BadRAM: mark 0x%lx with mask 0x%0lx\n", addr, mask);
do {
[...]
if (memblock_is_reserved(addr)) {
pr_debug("BadRAM: page %lu reserved by kernel\n", pfn);
is_reserved++;
continue;
}
[...]
pr_debug("BadRAM: page %lu (addr 0x%0lx) marked bad "
"[total %lu]\n", pfn, addr, pagecount);
} while (next_masked_address(&addr, mask));
if (is_reserved)
printk(KERN_WARNING "BadRAM: %lu page(s) already reserved and "
"could not be marked bad\n", is_reserved);
return pagecount;
}
This way everything with possibly high volume log output is guarded by
pr_debug and only the summary gets printed by default. No log_buf
cluttering but also a bit harder to debug for somebody who's interested
in finding out which pages are already reserved.
Stefan
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