From: Andrew Morton <akpm@linux-foundation.org>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>, Hao Luo <haoluo@google.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
bpf@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-perf-users@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
Stanislav Fomichev <sdf@google.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Namhyung Kim <namhyung@gmail.com>
Subject: Re: [PATCH RFC v2 bpf-next 1/9] mm: Store build id in inode object
Date: Tue, 28 Feb 2023 11:13:10 -0800 [thread overview]
Message-ID: <20230228111310.05f339a0a1a00e919859ffad@linux-foundation.org> (raw)
In-Reply-To: <20230228093206.821563-2-jolsa@kernel.org>
On Tue, 28 Feb 2023 10:31:58 +0100 Jiri Olsa <jolsa@kernel.org> wrote:
> Storing build id in file's inode object for elf executable with build
> id defined. The build id is stored when file is mmaped.
>
> This is enabled with new config option CONFIG_INODE_BUILD_ID.
>
> The build id is valid only when the file with given inode is mmap-ed.
>
> We store either the build id itself or the error we hit during
> the retrieval.
>
> ...
>
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -699,6 +700,12 @@ struct inode {
> struct fsverity_info *i_verity_info;
> #endif
>
> +#ifdef CONFIG_INODE_BUILD_ID
> + /* Initialized and valid for executable elf files when mmap-ed. */
> + struct build_id *i_build_id;
> + spinlock_t i_build_id_lock;
> +#endif
> +
Remember we can have squillions of inodes in memory. So that's one
costly spinlock!
AFAICT this lock could be removed if mmap_region() were to use an
atomic exchange on inode->i_build_id?
If not, can we use an existing lock? i_lock would be appropriate
(don't forget to update its comment).
Also, the code in mmap_region() runs build_id_free() inside the locked
region, which seems unnecessary.
next prev parent reply other threads:[~2023-02-28 19:13 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-28 9:31 [RFC v2 bpf-next 0/9] mm/bpf/perf: " Jiri Olsa
2023-02-28 9:31 ` [PATCH RFC v2 bpf-next 1/9] mm: " Jiri Olsa
2023-02-28 19:13 ` Andrew Morton [this message]
2023-03-01 8:16 ` Jiri Olsa
2023-02-28 9:31 ` [PATCH RFC v2 bpf-next 2/9] bpf: Use file's inode object build id in stackmap Jiri Olsa
2023-02-28 9:32 ` [PATCH RFC v2 bpf-next 3/9] perf: Use file object build id in perf_event_mmap_event Jiri Olsa
2023-02-28 9:32 ` [PATCH RFC v2 bpf-next 4/9] libbpf: Allow to resolve binary path in current directory Jiri Olsa
2023-03-08 1:19 ` Andrii Nakryiko
2023-03-08 13:48 ` Jiri Olsa
2023-02-28 9:32 ` [PATCH RFC v2 bpf-next 5/9] selftests/bpf: Add read_buildid function Jiri Olsa
2023-03-08 1:22 ` Andrii Nakryiko
2023-03-08 13:49 ` Jiri Olsa
2023-02-28 9:32 ` [PATCH RFC v2 bpf-next 6/9] selftests/bpf: Add err.h header Jiri Olsa
2023-02-28 9:32 ` [PATCH RFC v2 bpf-next 7/9] selftests/bpf: Replace extract_build_id with read_build_id Jiri Olsa
2023-03-08 1:26 ` Andrii Nakryiko
2023-03-08 13:51 ` Jiri Olsa
2023-02-28 9:32 ` [PATCH RFC v2 bpf-next 8/9] selftests/bpf: Add inode_build_id test Jiri Olsa
2023-02-28 9:32 ` [PATCH RFC v2 bpf-next 9/9] selftests/bpf: Add iter_task_vma_buildid test Jiri Olsa
2023-03-08 1:32 ` Andrii Nakryiko
2023-03-08 14:00 ` Jiri Olsa
2023-02-28 22:07 ` [RFC v2 bpf-next 0/9] mm/bpf/perf: Store build id in inode object Dave Chinner
2023-03-01 15:41 ` Arnaldo Carvalho de Melo
2023-03-02 8:41 ` Jiri Olsa
2023-03-02 8:35 ` Jiri Olsa
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