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[34.90.104.202]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c170591172esm58080666b.15.2026.07.17.03.59.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Jul 2026 03:59:02 -0700 (PDT) From: Joshua Crofts To: Ryusuke Konishi , Viacheslav Dubeyko Cc: linux-nilfs@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+cae54346a70bbceeff2c@syzkaller.appspotmail.com Subject: [PATCH v2] nilfs2: fix infinite loop in nilfs_clean_segments() Date: Fri, 17 Jul 2026 10:58:54 +0000 Message-ID: <20260717105854.1380-1-joshua.crofts1@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" syzbot reported a hung task in nilfs_transaction_begin(). This occurs because the cleaner ioctl falls into an infinite loop if nilfs_segctor_construct() repeatedly returns -EROFS (e.g. the device is remounted as read-only after an I/O error). Currently in nilfs_clean_segments(), if err is non-zero, it logs the error and sleeps but doesn't abort when it encounters a terminal error like -EROFS. This causes the thread to loop forever. Fix this by breaking out of the loop if nilfs_segctor_construct() returns -EROFS. This matches the behaviour in nilfs_segctor_write_out(), which also handles -EROFS. Reported-by: syzbot+cae54346a70bbceeff2c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Dcae54346a70bbceeff2c Fixes: 9ff05123e3bf ("nilfs2: segment constructor") Assisted-by: gemini:gemini-3.1-pro Signed-off-by: Joshua Crofts Acked-by: Ryusuke Konishi --- Changes in v2: - use `goto out_unlock` instead of break to prevent discard commands from being sent As much as I've tried, syzbot is unable to test this and always fails with "FATAL: Kernel too old". Nevertheless, I've tested the patch with the same reproducer in QEMU and the system didn't hang. --- fs/nilfs2/segment.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c index 9332f5ac6..218926789 100644 --- a/fs/nilfs2/segment.c +++ b/fs/nilfs2/segment.c @@ -2561,6 +2561,10 @@ int nilfs_clean_segments(struct super_block *sb, str= uct nilfs_argv *argv, break; =20 nilfs_warn(sb, "error %d cleaning segments", err); + + if (unlikely(err =3D=3D -EROFS)) + goto out_unlock; + set_current_state(TASK_INTERRUPTIBLE); schedule_timeout(sci->sc_interval); } --=20 2.47.3