On Thu, Feb 09, 2012 at 11:29:36AM +0900, KAMEZAWA Hiroyuki wrote: > On Wed, 8 Feb 2012 10:51:42 -0500 > Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote: > > > Currently a local variable of pagemap entry in pagemap_pte_range() > > is named pfn and typed with u64, but it's not correct (pfn should > > be unsigned long.) > > Does this means "the name 'pfn' implies unsigned long, usually. And > this usage is confusing." ? Yes, that is one I meant. And another meaning is that this variable can contain not only page frame number but also other information about page state. The format of pagemap entry is described in a comment above pagemap_read() like this * Bits 0-55 page frame number (PFN) if present * Bits 0-4 swap type if swapped * Bits 5-55 swap offset if swapped * Bits 55-60 page shift (page size = 1<<page shift) * Bit 61 reserved for future use * Bit 62 page swapped * Bit 63 page present * * If the page is not present but in swap, then the PFN contains an * encoding of the swap file number and the page's offset into the * swap. Unmapped pages return a null PFN. This allows determining * precisely which pages are mapped (or in swap) and comparing mapped * pages between processes. . So the name 'pfn' does not exactly match what it represents. > > This patch introduces special type for pagemap entry and replace > > code with it. > > > > Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > > > Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Thank you. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>