On Thu, 26 Jul 2012 17:35:13 +0800 Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx> wrote: > > Is this patch really safe for all architectures? > > > > IS_ERR_VALUE() casts -MAX_ERRNO to unsigned long and then does comparison. > > Isn't it possible to conflict with valid pfns? > > > > See IS_ERR_VALUE(): > > #define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO) > > The minimal value of the error code is: > 0xffff f001 on 32-bit and 0x ffff ffff ffff f001 on 64-bit, > it is fair larger that a valid pfn (for the pfn, the most top of 12 bits > are always 0). > > Note, PAE is a special case, but only 64G physical memory is valid, > 0xffff f001 is also suitable for that. Ah, I see. I misread the type pfn_t and was confused. Thank you! Takuya -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
