Re: [PATCH] MIPS: fix pfn_valid() for FLAGMEM

[Ralf Baechle <ralf@linux-mips.org>]

On Thu, Oct 08, 2009 at 04:57:32PM +0800, Wu Zhangjin wrote:

> When CONFIG_FLAGMEM enabled, STD/Hiberation will fail on YeeLoong
> laptop, This patch fix it:
> 
> if pfn is between min_low_pfn and max_mapnr, the old pfn_valid() will
> return TRUE, but in reality, if the memory is not continuous, it should
> be false. for example:

Hm...  All that pfn_valid() indicates is that a page frame number is valid
to index a pfn.  That is that a pfn is valid to index the mem_map array.

> $ cat /proc/iomem | grep "System RAM"
> 00000000-0fffffff : System RAM
> 90000000-bfffffff : System RAM
> 
> as we can see, it is not continuous, so, some of the memory is not valid
> but regarded as valid by pfn_valid(), and at last make STD/Hibernate
> fail when shrinking a too large number of invalid memory.
> 
> Here, we fix it via checking pfn is in the "System RAM" or not, if yes,
> return TRUE.

Are the non-memory parts marked as reserved?

  Ralf