From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "T.J. Mercier" <tjmercier@google.com>, <daniel@iogearbox.net>,
<andrii@kernel.org>, <eddyz87@gmail.com>, <memxor@gmail.com>,
<martin.lau@linux.dev>, <song@kernel.org>,
<yonghong.song@linux.dev>, <jolsa@kernel.org>,
<emil@etsalapatis.com>, <ihor.solodrai@linux.dev>,
<mykyta.yatsenko5@gmail.com>
Cc: <bpf@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next v5 1/2] bpf: htab: Split htab_elem_lru and htab_elem_pcpu off of htab_elem
Date: Mon, 21 Sep 2026 00:51:12 +0000 [thread overview]
Message-ID: <DLKKZEHWGP2Y.2C0DPQW74COKW@gmail.com> (raw)
In-Reply-To: <20260921002206.184660-2-tjmercier@google.com>
On Sun, Sep 20, 2026 at 05:22 PM T.J. Mercier <tjmercier@google.com> wrote:
> - if ((u64)attr->key_size + attr->value_size >= KMALLOC_MAX_SIZE -
> - sizeof(struct htab_elem))
> + if (round_up((u64)attr->key_size, 8) + round_up((u64)attr->value_size, 8) >=
> + KMALLOC_MAX_SIZE - sizeof(union htab_elem_all))
sizeof(union htab_elem_all) is the same 48 bytes as before.
The round_up() part is an unrelated change in what map_create accepts.
Drop it from this patch.
[...]
> + if (htab_is_lru(htab))
> + elem_offset = offsetof(struct htab_elem_lru, elem);
> + else if (percpu && !prealloc)
> + elem_offset = offsetof(struct htab_elem_pcpu, elem);
> +
> + BUILD_BUG_ON(elem_offset + sizeof(struct htab_elem) >
> + sizeof(union htab_elem_all));
elem_offset is a run-time value. BUILD_BUG_ON() works here only when
the compiler manages to fold it, and it cannot trigger by construction
of the union. Drop it.
next prev parent reply other threads:[~2026-09-21 0:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-21 0:22 [PATCH bpf-next v5 0/2] bpf: htab: Reduce memory use of hash maps T.J. Mercier
2026-09-21 0:22 ` [PATCH bpf-next v5 1/2] bpf: htab: Split htab_elem_lru and htab_elem_pcpu off of htab_elem T.J. Mercier
2026-09-21 0:51 ` Alexei Starovoitov [this message]
2026-09-21 16:40 ` T.J. Mercier
2026-09-21 0:22 ` [PATCH bpf-next v5 2/2] bpf: htab: Reduce elem_size by 8 bytes for small key sizes T.J. Mercier
2026-09-21 0:57 ` Alexei Starovoitov
2026-09-21 16:34 ` T.J. Mercier
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