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Wed, 02 Apr 2025 09:10:52 -0700 (PDT) Received: from localhost.localdomain ([14.139.69.34]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2291f1fa0a5sm110205435ad.240.2025.04.02.09.10.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Apr 2025 09:10:51 -0700 (PDT) From: Bharadwaj Raju To: kent.overstreet@linux.dev Cc: Bharadwaj Raju , linux-bcachefs@vger.kernel.org, shuah@kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linux.dev, syzbot+c82cd2906e2f192410bb@syzkaller.appspotmail.com Subject: [PATCH] bcachefs: don't call sleeping funcs when handling inconsistency errors Date: Wed, 2 Apr 2025 21:40:40 +0530 Message-ID: <20250402161043.161795-1-bharadwaj.raju777@gmail.com> X-Mailer: git-send-email 2.49.0 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" In bch2_bkey_pick_read_device, we're in an RCU lock. So, we can't call any potentially-sleeping functions. However, we call bch2_dev_rcu, which calls bch2_fs_inconsistent in its error case. That then calls bch2_prt_print on a non-atomic printbuf, as well as uses the blocking variant of bch2_print_string_as_lines, both of which lead to calls to potentially-sleeping functions, namely krealloc with GFP_KERNEL and console_lock respectively. Give a nonzero atomic to the printbuf, and use the nonblocking variant of bch2_print_string_as_lines. Reported-by: syzbot+c82cd2906e2f192410bb@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Dc82cd2906e2f192410bb Signed-off-by: Bharadwaj Raju --- fs/bcachefs/error.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/bcachefs/error.c b/fs/bcachefs/error.c index d4dfd13a8076..6f0f2f12c004 100644 --- a/fs/bcachefs/error.c +++ b/fs/bcachefs/error.c @@ -60,6 +60,8 @@ static bool bch2_fs_trans_inconsistent(struct bch_fs *c, = struct btree_trans *tra { struct printbuf buf =3D PRINTBUF; =20 + buf.atomic++; + bch2_log_msg_start(c, &buf); =20 prt_vprintf(&buf, fmt, args); @@ -68,7 +70,9 @@ static bool bch2_fs_trans_inconsistent(struct bch_fs *c, = struct btree_trans *tra if (trans) bch2_trans_updates_to_text(&buf, trans); bool ret =3D __bch2_inconsistent_error(c, &buf); - bch2_print_string_as_lines(KERN_ERR, buf.buf); + bch2_print_string_as_lines_nonblocking(KERN_ERR, buf.buf); + + buf.atomic--; =20 printbuf_exit(&buf); return ret; --=20 2.49.0