`kl-pageinfo`¶

Describe a struct page

Canonical: kernlens-pageinfo
Category: addresses & page tables
Synopsis: kl-pageinfo [-h] page

The reverse direction: given a struct page pointer, prints the virtual address it backs, the physical address, the pfn, and what the page currently is.

Options¶

Option	Argument	Meaning
	—	address of a struct page (head page)

From struct page to address¶

Invocation¶

kl-pageinfo 0xffffcd3b80010000

Output¶

Virtual: 0xffff90c340400000
Physical: 0x400000
page: 0xffffcd3b80010000
PFN: 1024  type: buddy
refcount: 0

Reading it¶

type: buddy is the most useful field: it says the page is on a buddy free list, which is what you expect for a free page. refcount: 0 agrees. On a 6.1 kernel the type comes from the PG_buddy flag, since the page_type ordinals used by 6.12+ do not exist yet -- the probe decides which encoding applies by asking whether enum pageflags still defines PG_slab.

Notes¶

A page that is allocated but not on any list reports a type of unknown or initialized; that is not a failure, it is the absence of a type tag. Use kl-slab details for a page that is a slab.

Part of the KernLens tutorial. Every output block on this page was captured from the kernel described in the tutorial index.

kl-pageinfo¶