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[107.197.105.120]) by smtp.gmail.com with ESMTPSA id 00721157ae682-658e4d2a7d1sm7620967b3.31.2024.07.10.08.33.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jul 2024 08:33:25 -0700 (PDT) From: Pei Li Date: Wed, 10 Jul 2024 08:33:24 -0700 Subject: [PATCH] Fix WARNING: suspicious RCU usage in bch2_bucket_ref_update Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20240710-bug10-v1-1-f1f8cf98f7c0@gmail.com> X-B4-Tracking: v=1; b=H4sIAMOpjmYC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyDHUUlJIzE vPSU3UzU4B8JSMDIxMDcwNL3aTSdEMDXbMkY1OTFENL4zQjAyWg2oKi1LTMCrA50bG1tQD9yXo mVwAAAA== To: Kent Overstreet , Brian Foster Cc: linux-bcachefs@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, syzkaller-bugs@googlegroups.com, linux-kernel-mentees@lists.linuxfoundation.org, syzbot+e74fea078710bbca6f4b@syzkaller.appspotmail.com, Pei Li X-Mailer: b4 0.15-dev-13183 X-Developer-Signature: v=1; a=ed25519-sha256; t=1720625604; l=2446; i=peili.dev@gmail.com; s=20240625; h=from:subject:message-id; bh=aTVeWmvuai/R1U1FoOT+kwJPiR7ddJ+S95lzMnEtAgA=; b=lNEuCBby2LIHOBFQJWiBICH9AZBveXtH9UVkQmYRmAgWXhsoMvc+l6pVvk2oNBW8QcqFuPWJ0 C6IMhyvlU+bCVZj0CNaulb1njfIn2W+HQzDS5UqsiFh1sRrCnbZesYL X-Developer-Key: i=peili.dev@gmail.com; a=ed25519; pk=I6GWb2uGzELGH5iqJTSK9VwaErhEZ2z2abryRD6a+4Q= When dereference ca->bucket_gens, we are expecting one of the three locks to be hold if ca->fs is not NULL. This patch acquires mark_lock before entering __mark_pointer() Note: testing is done by a robot and is best-effort only. To: Kent Overstreet To: Brian Foster Cc: linux-bcachefs@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: skhan@linuxfoundation.org Cc: syzkaller-bugs@googlegroups.com Cc: linux-kernel-mentees@lists.linuxfoundation.org Reported-by: syzbot+e74fea078710bbca6f4b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3De74fea078710bbca6f4b Tested-by: syzbot+e74fea078710bbca6f4b@syzkaller.appspotmail.com Signed-off-by: Pei Li --- Syzbot reported the following warning: fs/bcachefs/buckets.h:107 suspicious rcu_dereference_check() usage! When dereference ca->bucket_gens, we are expecting one of the three locks to be hold if ca->fs is not NULL. This patch acquires mark_lock before entering __mark_pointer() Tested on: commit: 34afb82a Merge tag '6.10-rc6-smb3-server-fixes' of git.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=3D1492e87e980000 kernel config: https://syzkaller.appspot.com/x/.config?x=3D42a432cfd0e579e0 dashboard link: https://syzkaller.appspot.com/bug?extid=3De74fea078710bbca6= f4b compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debia= n) 2.40 patch: https://syzkaller.appspot.com/x/patch.diff?x=3D15e2e87e9800= 00 Note: testing is done by a robot and is best-effort only. --- fs/bcachefs/buckets.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c index 743d57eba760..03147e46dc47 100644 --- a/fs/bcachefs/buckets.c +++ b/fs/bcachefs/buckets.c @@ -1033,8 +1033,14 @@ static int bch2_trigger_pointer(struct btree_trans *= trans, =20 if (flags & BTREE_TRIGGER_transactional) { struct bkey_i_alloc_v4 *a =3D bch2_trans_start_alloc_update(trans, bucke= t); + + percpu_down_read(&c->mark_lock); + ret =3D PTR_ERR_OR_ZERO(a) ?: __mark_pointer(trans, ca, k, &p.ptr, *sectors, bp.data_type, &a->v); + + percpu_up_read(&c->mark_lock); + if (ret) goto err; =20 --- base-commit: 256abd8e550ce977b728be79a74e1729438b4948 change-id: 20240709-bug10-6b354d193f20 Best regards, --=20 Pei Li