From: Hou Tao <houtao@huaweicloud.com>
To: bpf@vger.kernel.org, linux-mm@kvack.org
Cc: Martin KaFai Lau <martin.lau@linux.dev>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>, Song Liu <song@kernel.org>,
Hao Luo <haoluo@google.com>,
Yonghong Song <yonghong.song@linux.dev>,
Daniel Borkmann <daniel@iogearbox.net>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Jiri Olsa <jolsa@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
houtao1@huawei.com, Dennis Zhou <dennis@kernel.org>,
Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@linux.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH bpf-next v2 1/7] mm/percpu.c: don't acquire pcpu_lock for pcpu_chunk_addr_search()
Date: Wed, 18 Oct 2023 19:33:37 +0800 [thread overview]
Message-ID: <20231018113343.2446300-2-houtao@huaweicloud.com> (raw)
In-Reply-To: <20231018113343.2446300-1-houtao@huaweicloud.com>
From: Hou Tao <houtao1@huawei.com>
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().
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
mm/percpu.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index 7b40b3963f10..76b9c5e63c56 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);
--
2.29.2
next prev parent reply other threads:[~2023-10-18 11:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-18 11:33 [PATCH bpf-next v2 0/7] bpf: Fixes for per-cpu kptr Hou Tao
2023-10-18 11:33 ` Hou Tao [this message]
2023-10-20 3:55 ` [PATCH bpf-next v2 1/7] mm/percpu.c: don't acquire pcpu_lock for pcpu_chunk_addr_search() Dennis Zhou
2023-10-18 11:33 ` [PATCH bpf-next v2 2/7] mm/percpu.c: introduce pcpu_alloc_size() Hou Tao
2023-10-20 2:18 ` Alexei Starovoitov
2023-10-20 4:09 ` Dennis Zhou
2023-10-20 4:16 ` Alexei Starovoitov
2023-10-20 7:09 ` Hou Tao
2023-10-18 11:33 ` [PATCH bpf-next v2 3/7] bpf: Re-enable unit_size checking for global per-cpu allocator Hou Tao
2023-10-18 11:33 ` [PATCH bpf-next v2 4/7] bpf: Use pcpu_alloc_size() in bpf_mem_free{_rcu}() Hou Tao
2023-10-18 11:33 ` [PATCH bpf-next v2 5/7] bpf: Move the declaration of __bpf_obj_drop_impl() to bpf.h Hou Tao
2023-10-18 11:33 ` [PATCH bpf-next v2 6/7] bpf: Use bpf_global_percpu_ma for per-cpu kptr in __bpf_obj_drop_impl() Hou Tao
2023-10-18 11:33 ` [PATCH bpf-next v2 7/7] selftests/bpf: Add more test cases for bpf memory allocator Hou Tao
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