bpf: Replace bpf memory allocator with kmalloc_nolock() in local storage

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Replace bpf memory allocator with kmalloc_nolock() to reduce memory
wastage due to preallocation.

In bpf_selem_free(), an selem now needs to wait for a RCU grace period
before being freed when reuse_now == true. Therefore, rcu_barrier()
should be always be called in bpf_local_storage_map_free().

In bpf_local_storage_free(), since smap->storage_ma is no longer needed
to return the memory, the function is now independent from smap.

Remove the outdated comment in bpf_local_storage_alloc(). We already
free selem after an RCU grace period in bpf_local_storage_update() when
bpf_local_storage_alloc() failed the cmpxchg since commit c0d63f3091
("bpf: Add bpf_selem_free()").

Signed-off-by: Amery Hung <ameryhung@gmail.com>
Reviewed-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20251114201329.3275875-5-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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This commit is contained in:

Amery Hung 2025-11-14 12:13:26 -08:00 • committed by Alexei Starovoitov

parent 39a460c425

commit f484f4a3e0

2 changed files with 48 additions and 112 deletions

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8

include/linux/bpf_local_storage.h

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162

kernel/bpf/bpf_local_storage.c

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