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From: Pasha Tatashin <pasha.tatashin@soleen.com>
Date: Tue, 14 May 2024 10:35:40 -0600
Message-ID: <CA+CK2bCFWoLL0o2s=WnUyxPaDD09OeuHK5gqkLc6UiGC7r5sRQ@mail.gmail.com>
Subject: Re: [PATCH v2 1/1] lib: add version into /proc/allocinfo output
To: Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, vbabka@suse.cz, 
	keescook@chromium.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, 
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, May 14, 2024 at 10:31=E2=80=AFAM Suren Baghdasaryan <surenb@google.=
com> wrote:
>
> Add version string and a header at the beginning of /proc/allocinfo to
> allow later format changes. Example output:
>
> > head /proc/allocinfo
> allocinfo - version: 1.0
> #     <size>  <calls> <tag info>
>            0        0 init/main.c:1314 func:do_initcalls
>            0        0 init/do_mounts.c:353 func:mount_nodev_root
>            0        0 init/do_mounts.c:187 func:mount_root_generic
>            0        0 init/do_mounts.c:158 func:do_mount_root
>            0        0 init/initramfs.c:493 func:unpack_to_rootfs
>            0        0 init/initramfs.c:492 func:unpack_to_rootfs
>            0        0 init/initramfs.c:491 func:unpack_to_rootfs
>          512        1 arch/x86/events/rapl.c:681 func:init_rapl_pmus
>          128        1 arch/x86/events/rapl.c:571 func:rapl_cpu_online
>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>

Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>

Thank you,
Pasha

> ---
> Changes since v1 [1]:
> - Added header with field names, per Pasha Tatashin
> - Fixed a spelling error in the changelog
>
> [1] https://lore.kernel.org/all/20240514153532.3622371-1-surenb@google.co=
m/
>
>  Documentation/filesystems/proc.rst |  5 ++--
>  lib/alloc_tag.c                    | 48 ++++++++++++++++++++----------
>  2 files changed, 36 insertions(+), 17 deletions(-)
>
> diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesyste=
ms/proc.rst
> index 245269dd6e02..4b71b3903d46 100644
> --- a/Documentation/filesystems/proc.rst
> +++ b/Documentation/filesystems/proc.rst
> @@ -961,13 +961,14 @@ Provides information about memory allocations at al=
l locations in the code
>  base. Each allocation in the code is identified by its source file, line
>  number, module (if originates from a loadable module) and the function c=
alling
>  the allocation. The number of bytes allocated and number of calls at eac=
h
> -location are reported.
> +location are reported. The first line indicates the version of the file,=
 the
> +second line is the header listing fields in the file.
>
>  Example output.
>
>  ::
>
> -    > sort -rn /proc/allocinfo
> +    > tail -n +3 /proc/allocinfo | sort -rn
>     127664128    31168 mm/page_ext.c:270 func:alloc_page_ext
>      56373248     4737 mm/slub.c:2259 func:alloc_slab_page
>      14880768     3633 mm/readahead.c:247 func:page_cache_ra_unbounded
> diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> index 531dbe2f5456..cbe93939332d 100644
> --- a/lib/alloc_tag.c
> +++ b/lib/alloc_tag.c
> @@ -16,47 +16,61 @@ EXPORT_SYMBOL(_shared_alloc_tag);
>  DEFINE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,
>                         mem_alloc_profiling_key);
>
> +struct allocinfo_private {
> +       struct codetag_iterator iter;
> +       bool print_header;
> +
> +};
> +
>  static void *allocinfo_start(struct seq_file *m, loff_t *pos)
>  {
> -       struct codetag_iterator *iter;
> +       struct allocinfo_private *priv;
>         struct codetag *ct;
>         loff_t node =3D *pos;
>
> -       iter =3D kzalloc(sizeof(*iter), GFP_KERNEL);
> -       m->private =3D iter;
> -       if (!iter)
> +       priv =3D kzalloc(sizeof(*priv), GFP_KERNEL);
> +       m->private =3D priv;
> +       if (!priv)
>                 return NULL;
>
> +       priv->print_header =3D (node =3D=3D 0);
>         codetag_lock_module_list(alloc_tag_cttype, true);
> -       *iter =3D codetag_get_ct_iter(alloc_tag_cttype);
> -       while ((ct =3D codetag_next_ct(iter)) !=3D NULL && node)
> +       priv->iter =3D codetag_get_ct_iter(alloc_tag_cttype);
> +       while ((ct =3D codetag_next_ct(&priv->iter)) !=3D NULL && node)
>                 node--;
>
> -       return ct ? iter : NULL;
> +       return ct ? priv : NULL;
>  }
>
>  static void *allocinfo_next(struct seq_file *m, void *arg, loff_t *pos)
>  {
> -       struct codetag_iterator *iter =3D (struct codetag_iterator *)arg;
> -       struct codetag *ct =3D codetag_next_ct(iter);
> +       struct allocinfo_private *priv =3D (struct allocinfo_private *)ar=
g;
> +       struct codetag *ct =3D codetag_next_ct(&priv->iter);
>
>         (*pos)++;
>         if (!ct)
>                 return NULL;
>
> -       return iter;
> +       return priv;
>  }
>
>  static void allocinfo_stop(struct seq_file *m, void *arg)
>  {
> -       struct codetag_iterator *iter =3D (struct codetag_iterator *)m->p=
rivate;
> +       struct allocinfo_private *priv =3D (struct allocinfo_private *)m-=
>private;
>
> -       if (iter) {
> +       if (priv) {
>                 codetag_lock_module_list(alloc_tag_cttype, false);
> -               kfree(iter);
> +               kfree(priv);
>         }
>  }
>
> +static void print_allocinfo_header(struct seq_buf *buf)
> +{
> +       /* Output format version, so we can change it. */
> +       seq_buf_printf(buf, "allocinfo - version: 1.0\n");
> +       seq_buf_printf(buf, "#     <size>  <calls> <tag info>\n");
> +}
> +
>  static void alloc_tag_to_text(struct seq_buf *out, struct codetag *ct)
>  {
>         struct alloc_tag *tag =3D ct_to_alloc_tag(ct);
> @@ -71,13 +85,17 @@ static void alloc_tag_to_text(struct seq_buf *out, st=
ruct codetag *ct)
>
>  static int allocinfo_show(struct seq_file *m, void *arg)
>  {
> -       struct codetag_iterator *iter =3D (struct codetag_iterator *)arg;
> +       struct allocinfo_private *priv =3D (struct allocinfo_private *)ar=
g;
>         char *bufp;
>         size_t n =3D seq_get_buf(m, &bufp);
>         struct seq_buf buf;
>
>         seq_buf_init(&buf, bufp, n);
> -       alloc_tag_to_text(&buf, iter->ct);
> +       if (priv->print_header) {
> +               print_allocinfo_header(&buf);
> +               priv->print_header =3D false;
> +       }
> +       alloc_tag_to_text(&buf, priv->iter.ct);
>         seq_commit(m, seq_buf_used(&buf));
>         return 0;
>  }
>
> base-commit: 7e8aafe0636cdcc5c9699ced05ff1f8ffcb937e2
> --
> 2.45.0.rc1.225.g2a3ae87e7f-goog
>