> bpf: Add memory usage for arena
>
> arena is the only map type whose map_mem_usage() still returns 0, so
> "bpftool map show" and fdinfo always showed 0 memlock for an arena no
> matter how many pages it had.
>
> Count the pages that are actually mapped into the arena: bump a counter in
> apply_range_set_cb() when a page goes in and drop it in
> apply_range_clear_cb() when a page goes out, both under the arena
> spinlock.
> map_mem_usage() then just returns nr_pages << PAGE_SHIFT.
>
> Only real data pages are counted, not the scratch page.
>
> Signed-off-by: Jiayuan Chen <[email protected]>
This looks like a fix for a user-visible bug: arena's map_mem_usage()
always returned 0, so bpftool map show and fdinfo reported 0 memlock
regardless of how many pages the arena had. The returns-0 stub was added
together with kernel/bpf/arena.c. Should this include:
Fixes: 317460317a02 ("bpf: Introduce bpf_arena.")
---
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See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/29508297958
