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[87.222.102.98]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49ce5563c6csm107207695e9.4.2026.09.03.08.24.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Sep 2026 08:24:39 -0700 (PDT) From: Miguel Garcia To: stable@vger.kernel.org Cc: pvmohammedanees2003@gmail.com, akpm@linux-foundation.org, joseph.qi@linux.alibaba.com, mark@fasheh.com, jlbec@evilplan.org, ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH 5.15.y] ocfs2: fix deadlock in ocfs2_get_system_file_inode Date: Thu, 3 Sep 2026 17:24:35 +0200 Message-ID: <20260903152435.1801594-1-miguelgarciaroman8@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" From: Mohammed Anees commit 7bf1823e010e8db2fb649c790bd1b449a75f52d8 upstream. syzbot has found a possible deadlock in ocfs2_get_system_file_inode [1]. The scenario is depicted here, CPU0 CPU1 lock(&ocfs2_file_ip_alloc_sem_key); lock(&osb->system_file_mutex); lock(&ocfs2_file_ip_alloc_sem_key); lock(&osb->system_file_mutex); The function calls which could lead to this are: CPU0 ocfs2_mknod - lock(&ocfs2_file_ip_alloc_sem_key); =2E =2E =2E ocfs2_get_system_file_inode - lock(&osb->system_file_mutex); CPU1 - ocfs2_fill_super - lock(&osb->system_file_mutex); =2E =2E =2E ocfs2_read_virt_blocks - lock(&ocfs2_file_ip_alloc_sem_key); This issue can be resolved by making the down_read -> down_read_try in the ocfs2_read_virt_blocks. [1] https://syzkaller.appspot.com/bug?extid=3De0055ea09f1f5e6fabdd Link: https://lkml.kernel.org/r/20240924093257.7181-1-pvmohammedanees2003@g= mail.com Signed-off-by: Mohammed Anees Reviewed-by: Joseph Qi Reported-by: Closes: https://syzkaller.appspot.com/bug?extid=3De0055ea09f1f5e6fabdd Tested-by: syzbot+e0055ea09f1f5e6fabdd@syzkaller.appspotmail.com Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Gang He Cc: Jun Piao Cc: Signed-off-by: Andrew Morton Signed-off-by: Miguel Garcia --- fs/ocfs2/extent_map.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c index bb3a56b7f9a7c..5e86c7e2c8212 100644 --- a/fs/ocfs2/extent_map.c +++ b/fs/ocfs2/extent_map.c @@ -981,7 +981,13 @@ int ocfs2_read_virt_blocks(struct inode *inode, u64 v_= block, int nr, } =20 while (done < nr) { - down_read(&OCFS2_I(inode)->ip_alloc_sem); + if (!down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem)) { + rc =3D -EAGAIN; + mlog(ML_ERROR, + "Inode #%llu ip_alloc_sem is temporarily unavailable\n", + (unsigned long long)OCFS2_I(inode)->ip_blkno); + break; + } rc =3D ocfs2_extent_map_get_blocks(inode, v_block + done, &p_block, &p_count, NULL); up_read(&OCFS2_I(inode)->ip_alloc_sem); --=20 2.43.0