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Fri, 09 Jan 2026 01:06:40 -0800 (PST) Received: from localhost ([2a12:a304:100::105b]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a3e3c491e7sm100826195ad.38.2026.01.09.01.06.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Jan 2026 01:06:40 -0800 (PST) From: Jinchao Wang To: Andreas Gruenbacher , gfs2@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Jinchao Wang , syzbot+092ef2e75c24d23f33c4@syzkaller.appspotmail.com Subject: [PATCH] gfs2: prevent sysfs duplicate name warning on mount Date: Fri, 9 Jan 2026 17:04:45 +0800 Message-ID: <20260109090451.1464893-2-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When mounting a GFS2 filesystem with a locktable name that already exists in the gfs2_kset, kobject_init_and_add() triggers a WARN() and a stack trace. This can be reproduced by a user attempting to mount two different images using the same fsid/locktable name. Check for the existence of the kobject using kset_find_obj() before attempting registration. If a collision is detected, return -EBUSY with an error message instead of allowing the kobject core to generate a stack dump. Reported-by: syzbot+092ef2e75c24d23f33c4@syzkaller.appspotmail.com Signed-off-by: Jinchao Wang --- Note: During testing with syzkaller, I noticed that after this fix prevents the sysfs WARN, a secondary "withdraw" warning still occurs in the GFS2 cleanup path. I believe this is a separate issue. fs/gfs2/sys.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c index 7051db9dbea0..06035e3d5829 100644 --- a/fs/gfs2/sys.c +++ b/fs/gfs2/sys.c @@ -720,6 +720,21 @@ int gfs2_sys_fs_add(struct gfs2_sbd *sdp) sprintf(ro, "RDONLY=3D%d", sb_rdonly(sb)); sprintf(spectator, "SPECTATOR=3D%d", sdp->sd_args.ar_spectator ? 1 : 0); =20 + /* + * Check for existence because kobject_init_and_add() warns + * with a dump_stack() if the name exists + */ + if (gfs2_kset) { + struct kobject *existing =3D kset_find_obj(gfs2_kset, sdp->sd_table_name= ); + + if (existing) { + kobject_put(existing); + fs_err(sdp, "fsid %s: sysfs entry already exists\n", + sdp->sd_table_name); + return -EBUSY; + } + } + init_completion(&sdp->sd_kobj_unregister); sdp->sd_kobj.kset =3D gfs2_kset; error =3D kobject_init_and_add(&sdp->sd_kobj, &gfs2_ktype, NULL, --=20 2.43.0