Re: [PATCH] [3/16] POISON: Handle poisoned pages in page free

[Minchan Kim]

On Wed, Apr 8, 2009 at 3:51 PM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>> >
>> > Â Â Â Â/*
>> > + Â Â Â Â* Page may have been marked bad before process is freeing it.
>> > + Â Â Â Â* Make sure it is not put back into the free page lists.
>> > + Â Â Â Â*/
>> > + Â Â Â if (PagePoison(page)) {
>> > + Â Â Â Â Â Â Â /* check more flags here... */
>>
>> How about adding WARNING with some information(ex, pfn, flags..).
>
> The memory_failure() code is already quite chatty. Don't think more
> noise is needed currently.

Sure.

> Or are you worrying about the case where a page gets corrupted
> by software and suddenly has Poison bits set? (e.g. 0xff everywhere).
> That would deserve a printk, but I'm not sure how to reliably test for
> that. After all a lot of flag combinations are valid.

I misunderstood your code.
That's because you add the code in bad_page.

As you commented, your intention was to prevent bad page from returning buddy.
Is right ?
If it is right, how about adding prevention code to free_pages_check ?
Now, bad_page is for showing the information that why it is bad page
I don't like emergency exit in bad_page.

> -Andi
>
> --
> ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
>



-- 
Kinds regards,
Minchan Kim
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/