Linux Page Cache Status

Question

I'm able to list page cache statuses in my OS by using page-types tool in Linux kernel source tree. Such as:

referenced,uptodate,lru,mappedtodisk

referenced,uptodate,lru,active,private

In source code there is whole list:

[KPF_LOCKED]    = "L:locked",
[KPF_ERROR]     = "E:error",
[KPF_REFERENCED]= "R:referenced",
[KPF_UPTODATE]  = "U:uptodate",
[KPF_DIRTY]     = "D:dirty",
[KPF_LRU]       = "l:lru",
[KPF_ACTIVE]    = "A:active",
[KPF_SLAB]      = "S:slab",
[KPF_WRITEBACK] = "W:writeback",
[KPF_RECLAIM]   = "I:reclaim",
[KPF_BUDDY]     = "B:buddy",
.......

But I couldn't find any information about what they mean, how kernel uses them etc. How can I find further information about types of page caches?

Answer 1

Try (in the kernel src tree)

Documentation/vm/pagemap.txt

-has some explanation on page flags..