From: Gautham Ananthakrishna gautham.ananthakrishna@oracle.com Subject: ocfs2: fix race between searching chunks and release journal_head from buffer_head
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.
Link: https://lkml.kernel.org/r/1634820718-6043-1-git-send-email-gautham.ananthakr... Signed-off-by: Gautham Ananthakrishna gautham.ananthakrishna@oracle.com Reviewed-by: Joseph Qi joseph.qi@linux.alibaba.com Cc: rajesh.sivaramasubramaniom@oracle.com Cc: Mark Fasheh mark@fasheh.com Cc: Joel Becker jlbec@evilplan.org Cc: Junxiao Bi junxiao.bi@oracle.com Cc: Changwei Ge gechangwei@live.cn Cc: Gang He ghe@suse.com Cc: Jun Piao piaojun@huawei.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
fs/ocfs2/suballoc.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-)
--- a/fs/ocfs2/suballoc.c~ocfs2-race-between-searching-chunks-and-release-journal_head-from-buffer_head +++ a/fs/ocfs2/suballoc.c @@ -1251,7 +1251,7 @@ static int ocfs2_test_bg_bit_allocatable { struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data; struct journal_head *jh; - int ret; + int ret = 1;
if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap)) return 0; @@ -1259,14 +1259,18 @@ static int ocfs2_test_bg_bit_allocatable if (!buffer_jbd(bg_bh)) return 1;
- jh = bh2jh(bg_bh); - spin_lock(&jh->b_state_lock); - bg = (struct ocfs2_group_desc *) jh->b_committed_data; - if (bg) - ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap); - else - ret = 1; - spin_unlock(&jh->b_state_lock); + jbd_lock_bh_journal_head(bg_bh); + if (buffer_jbd(bg_bh)) { + jh = bh2jh(bg_bh); + spin_lock(&jh->b_state_lock); + bg = (struct ocfs2_group_desc *) jh->b_committed_data; + if (bg) + ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap); + else + ret = 1; + spin_unlock(&jh->b_state_lock); + } + jbd_unlock_bh_journal_head(bg_bh);
return ret; } _