From: Hou Tao Date: Fri, 20 Oct 2023 13:31:56 +0000 (+0800) Subject: mm/percpu.c: don't acquire pcpu_lock for pcpu_chunk_addr_search() X-Git-Tag: io_uring-6.7-2023-11-10~40^2~28^2~14^2~6 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=394e6869f0185e89cb815db29bf819474df858ae;p=linux-2.6-block.git mm/percpu.c: don't acquire pcpu_lock for pcpu_chunk_addr_search() There is no need to acquire pcpu_lock for pcpu_chunk_addr_search(): 1) both pcpu_first_chunk & pcpu_reserved_chunk must have been initialized before the invocation of free_percpu(). 2) The dynamically-created chunk must be valid before the per-cpu pointers allocated from it are freed. So acquire pcpu_lock() after the invocation of pcpu_chunk_addr_search(). Acked-by: Dennis Zhou Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231020133202.4043247-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- diff --git a/mm/percpu.c b/mm/percpu.c index a7665de8485f..ea607078368d 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -2267,12 +2267,10 @@ void free_percpu(void __percpu *ptr) kmemleak_free_percpu(ptr); addr = __pcpu_ptr_to_addr(ptr); - - spin_lock_irqsave(&pcpu_lock, flags); - chunk = pcpu_chunk_addr_search(addr); off = addr - chunk->base_addr; + spin_lock_irqsave(&pcpu_lock, flags); size = pcpu_free_area(chunk, off); pcpu_memcg_free_hook(chunk, off, size);