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AJvYcCVM+DoDqunzT0aw0iqmVP1dPJCTxirFCwggomwEma4KD15ZBZEp3SgkhxLp79v4hezztzsVmuLlgA==@kvack.org X-Gm-Message-State: AOJu0Yzei5C0QK0WMxkaiWvp1eLtJi2P9XA4JWPLLs8gL8am9IDFnC/N L3hut6LpJCfDLvPLL6dVNg2enrCbfL1SEb6jdsBDtq/aA+dos12F16c22/QehEStFaLimWywtOw ojGXhcGNuygk9nL/jwpPckRakxmeM/bcaSVHY X-Gm-Gg: ASbGncswMYaEOwrJ1Am1/wgy+DsApDCRWrkqoY9QRrFn4FmkQKh9Hcjcv+d5IGOkIaX xznKCuVq2s0FZzDOF6YVO6fEpTUQ4AQLpcYm/wWOH5zxvZDZKdQogIYbODDTX3S3DQu0Gm4pE0n Widc5TMNkP7sqX6N/zqfKmA/wz4jVfpjY= X-Google-Smtp-Source: AGHT+IGUhxFmii7Q5/XDSbv8/CTslm1sdE9Xmzl9GrkcOz9ThZBXF8Us++3DNgGn3B84Bb0oly97rTFfFJeRUp/F54U= X-Received: by 2002:a05:622a:1a82:b0:476:f181:efeb with SMTP id d75a77b69052e-4946110541bmr1265301cf.16.1746825354587; Fri, 09 May 2025 14:15:54 -0700 (PDT) MIME-Version: 1.0 References: <20250507175500.204569-1-00107082@163.com> <20250509173929.42508-1-00107082@163.com> <7f237574d9f08a9fa8dcaa60d2edf8d8e91441d4.camel@linux.intel.com> <294d0743c0b2e5c409857ef81a6fe8baaf87727f.camel@linux.intel.com> In-Reply-To: From: Suren Baghdasaryan Date: Fri, 9 May 2025 14:15:43 -0700 X-Gm-Features: AX0GCFshryVG_JYj2Ron9JFNOnQXKXLnYo9eIyMWK7Xd04CyjIPVZiVJhGz52xs Message-ID: Subject: Re: [PATCH v2 2/2] alloc_tag: keep codetag iterator active between read() calls To: Tim Chen Cc: David Wang <00107082@163.com>, kent.overstreet@linux.dev, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: D943A40014 X-Stat-Signature: dgcbbx5xpsow6973xkhyiwrkig559xfx X-Rspam-User: X-HE-Tag: 1746825355-30869 X-HE-Meta: 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 YXDDoqWa obTl1Pi59LAc2lrkO0aCClzsFf3X6Ai/BpdGhwXKwVtEll7vfQg24QEQEZ73Bzq6bFsugV3YXL0/LIxzbUFO99Y7hzdPfhwMEyQI9+ouUi/M80jVaummLdkQ7fe2JhQl4YLEif26XWxj1LTsqM6csibZ6ab1sbI6prMRlgOPkxgItnqH5bvRYpX92Wr7Gz1T1/z1oQATguAdoNtO+4bTGrkom84fvB6iuzwfri2Xj+ZANqcY45GQ7qjrkBBiOlCy7jKE8VhBf06mjETyLNYGH6CqSiggT5WttFeXHhF2MAwL4QoiMzQ0ijh0cEXcTuSCF7LueaW2JgRIeUgiDncSiTs+wl60nMVym0KB3UfmZ4mJObCl1KyuAcOl1r+NF4HJsq84LRot/+cXwPA0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, May 9, 2025 at 1:46=E2=80=AFPM Suren Baghdasaryan wrote: > > On Fri, May 9, 2025 at 12:46=E2=80=AFPM Tim Chen wrote: > > > > On Fri, 2025-05-09 at 12:36 -0700, Suren Baghdasaryan wrote: > > > On Fri, May 9, 2025 at 11:33=E2=80=AFAM Tim Chen wrote: > > > > > > > > On Sat, 2025-05-10 at 01:39 +0800, David Wang wrote: > > > > > > > > > > > > > > > Signed-off-by: David Wang <00107082@163.com> > > > > > > Acked-by: Suren Baghdasaryan > > > > > > > > --- > > > > > lib/alloc_tag.c | 29 ++++++++++------------------- > > > > > 1 file changed, 10 insertions(+), 19 deletions(-) > > > > > > > > > > diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c > > > > > index 25ecc1334b67..fdd5887769a6 100644 > > > > > --- a/lib/alloc_tag.c > > > > > +++ b/lib/alloc_tag.c > > > > > @@ -45,21 +45,16 @@ struct allocinfo_private { > > > > > static void *allocinfo_start(struct seq_file *m, loff_t *pos) > > > > > { > > > > > struct allocinfo_private *priv; > > > > > - struct codetag *ct; > > > > > loff_t node =3D *pos; > > > > > > > > > > - priv =3D kzalloc(sizeof(*priv), GFP_KERNEL); > > > > > - m->private =3D priv; > > > > > - if (!priv) > > > > > - return NULL; > > > > > - > > > > > - priv->print_header =3D (node =3D=3D 0); > > > > > + priv =3D (struct allocinfo_private *)m->private; > > > > > codetag_lock_module_list(alloc_tag_cttype, true); > > > > > - priv->iter =3D codetag_get_ct_iter(alloc_tag_cttype); > > > > > - while ((ct =3D codetag_next_ct(&priv->iter)) !=3D NULL && n= ode) > > > > > - node--; > > > > > - > > > > > - return ct ? priv : NULL; > > > > > + if (node =3D=3D 0) { > > > > > + priv->print_header =3D true; > > > > > + priv->iter =3D codetag_get_ct_iter(alloc_tag_cttype= ); > > > > > + codetag_next_ct(&priv->iter); > > > > > + } > > > > > > > > Do you need to skip print header when *pos !=3D 0? i.e add > > > > > > Technically not needed since proc_create_seq_private() allocates > > > seq->private using kzalloc(), so the initial value of > > > priv->print_header is always false. > > > > But we'll start with first call to allocinfo_start() with *pos =3D=3D 0= , > > Usually but not always if we do lseek() to a non-zero position beforehand= . Actually, this change will break the lseek() case. We can't always assume that we start reading from *pos =3D=3D 0. Current patch will fail to initialize priv if we start reading with *pos !=3D 0. priv->iter should be tracking current position and allocinfo_start() should detect a mismatch between *pos and iter->pos and re-walk the tags if there was a position change. > > > then print_header will be initialized to true. > > After the first call to allocinfo_show() print_header will be reset > back to false. > > > Will there be subsequent calls of allocinfo_start() with *pos !=3D0, > > but priv->print_header stays at 0? > > Yes, there will be subsequent calls to allocinfo_start() with *pos !=3D0 > and priv->print_header=3Dfalse, which is what we want, right? We want to > print the header only at the beginning of the file (node =3D=3D 0). > > > > > Tim > > > > > > > > > > > } else { > > > > priv->print_header =3D false; > > > > } > > > > > > > > Tim > > > > > > > > > + return priv->iter.ct ? priv : NULL; > > > > > } > > > > > > > > > > >