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Wed, 20 Oct 2021 05:15:39 GMT Received: from gmananth-linux.oraclecorp.com (dhcp-10-76-40-219.vpn.oracle.com [10.76.40.219]) by userp3030.oracle.com with ESMTP id 3bqkuyeq9q-2; Wed, 20 Oct 2021 05:15:39 +0000 From: Gautham Ananthakrishna To: ocfs2-devel@oss.oracle.com Date: Wed, 20 Oct 2021 10:45:26 +0530 Message-Id: <1634706926-16201-2-git-send-email-gautham.ananthakrishna@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1634706926-16201-1-git-send-email-gautham.ananthakrishna@oracle.com> References: <1634706926-16201-1-git-send-email-gautham.ananthakrishna@oracle.com> Cc: rajesh.sivaramasubramaniom@oracle.com, gautham.ananthakrishna@oracle.com Subject: [Ocfs2-devel] [PATCH V1 RFC 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head X-BeenThere: ocfs2-devel@oss.oracle.com X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10142 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 suspectscore=0 malwarescore=0 bulkscore=0 phishscore=0 adultscore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109230001 definitions=main-2110200027 X-Proofpoint-ORIG-GUID: DwQURKn9cMxqMRdMPYwVisdkwtNyBC8d X-Proofpoint-GUID: DwQURKn9cMxqMRdMPYwVisdkwtNyBC8d Encountered a race between ocfs2_test_bg_bit_allocatable() and jbd2_journal_put_journal_head() resulting in the below vmcore. PID: 106879 TASK: ffff880244ba9c00 CPU: 2 COMMAND: "loop3" 0 [ffff8802435ff1c0] panic at ffffffff816ed175 1 [ffff8802435ff240] oops_end at ffffffff8101a7c9 2 [ffff8802435ff270] no_context at ffffffff8106eccf 3 [ffff8802435ff2e0] __bad_area_nosemaphore at ffffffff8106ef9d 4 [ffff8802435ff330] bad_area_nosemaphore at ffffffff8106f143 5 [ffff8802435ff340] __do_page_fault at ffffffff8106f80b 6 [ffff8802435ff3a0] do_page_fault at ffffffff8106fc2f 7 [ffff8802435ff3e0] page_fault at ffffffff816fd667 [exception RIP: ocfs2_block_group_find_clear_bits+316] RIP: ffffffffc11ef6fc RSP: ffff8802435ff498 RFLAGS: 00010206 RAX: 0000000000003918 RBX: 0000000000000001 RCX: 0000000000000018 RDX: 0000000000003918 RSI: 0000000000000000 RDI: ffff880060194040 RBP: ffff8802435ff4f8 R8: ffffffffff000000 R9: ffffffffffffffff R10: ffff8802435ff730 R11: ffff8802a94e5800 R12: 0000000000000007 R13: 0000000000007e00 R14: 0000000000003918 R15: ffff88017c973a28 ORIG_RAX: ffffffffffffffff CS: e030 SS: e02b 8 [ffff8802435ff490] ocfs2_block_group_find_clear_bits at ffffffffc11ef680 [ocfs2] 9 [ffff8802435ff500] ocfs2_cluster_group_search at ffffffffc11ef916 [ocfs2] 10 [ffff8802435ff580] ocfs2_search_chain at ffffffffc11f0fb6 [ocfs2] 11 [ffff8802435ff660] ocfs2_claim_suballoc_bits at ffffffffc11f1b1b [ocfs2] 12 [ffff8802435ff6f0] __ocfs2_claim_clusters at ffffffffc11f32cb [ocfs2] 13 [ffff8802435ff770] ocfs2_claim_clusters at ffffffffc11f5caf [ocfs2] 14 [ffff8802435ff780] ocfs2_local_alloc_slide_window at ffffffffc11cc0db [ocfs2] 15 [ffff8802435ff820] ocfs2_reserve_local_alloc_bits at ffffffffc11ce53f [ocfs2] 16 [ffff8802435ff890] ocfs2_reserve_clusters_with_limit at ffffffffc11f59b5 [ocfs2] 17 [ffff8802435ff8e0] ocfs2_reserve_clusters at ffffffffc11f5c88 [ocfs2] 18 [ffff8802435ff8f0] ocfs2_lock_refcount_allocators at ffffffffc11dc169 [ocfs2] 19 [ffff8802435ff960] ocfs2_make_clusters_writable at ffffffffc11e4274 [ocfs2] 20 [ffff8802435ffa50] ocfs2_replace_cow at ffffffffc11e4df1 [ocfs2] 21 [ffff8802435ffac0] ocfs2_refcount_cow at ffffffffc11e54b1 [ocfs2] 22 [ffff8802435ffb80] ocfs2_file_write_iter at ffffffffc11bf8f4 [ocfs2] 23 [ffff8802435ffcd0] lo_rw_aio at ffffffff814a1b5d 24 [ffff8802435ffd80] loop_queue_work at ffffffff814a2802 25 [ffff8802435ffe60] kthread_worker_fn at ffffffff810a80d2 26 [ffff8802435ffec0] kthread at ffffffff810a7afb 27 [ffff8802435fff50] ret_from_fork at ffffffff816f7da1 When ocfs2_test_bg_bit_allocatable() called bh2jh(bg_bh), the bg_bh->b_private NULL as jbd2_journal_put_journal_head() raced and released the jounal head from the buffer head. Needed to take bit lock for the bit 'BH_JournalHead' to fix this race. Signed-off-by: Gautham Ananthakrishna Signed-off-by: Gautham Ananthakrishna --- fs/ocfs2/suballoc.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c index 8521942..86f33f2 100644 --- a/fs/ocfs2/suballoc.c +++ b/fs/ocfs2/suballoc.c @@ -1256,9 +1256,17 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh, if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap)) return 0; + /* Fast path */ if (!buffer_jbd(bg_bh)) return 1; + /* Slow path */ + jbd_lock_bh_journal_head(bg_bh); + if (!buffer_jbd(bg_bh)){ + jbd_unlock_bh_journal_head(bg_bh); + return 1; + } + jh = bh2jh(bg_bh); spin_lock(&jh->b_state_lock); bg = (struct ocfs2_group_desc *) jh->b_committed_data; @@ -1267,6 +1275,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh, else ret = 1; spin_unlock(&jh->b_state_lock); + jbd_unlock_bh_journal_head(bg_bh); return ret; }