This is a note to let you know that I've just added the patch titled ocfs2: fix race between searching chunks and release journal_head from buffer_head to the 5.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ocfs2-fix-race-between-searching-chunks-and-release-journal_head-from-buffer_head.patch and it can be found in the queue-5.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 6f1b228529ae49b0f85ab89bcdb6c365df401558 Mon Sep 17 00:00:00 2001 From: Gautham Ananthakrishna <gautham.ananthakrishna@xxxxxxxxxx> Date: Thu, 28 Oct 2021 14:36:17 -0700 Subject: ocfs2: fix race between searching chunks and release journal_head from buffer_head From: Gautham Ananthakrishna <gautham.ananthakrishna@xxxxxxxxxx> commit 6f1b228529ae49b0f85ab89bcdb6c365df401558 upstream. 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" Call trace: panic oops_end no_context __bad_area_nosemaphore bad_area_nosemaphore __do_page_fault do_page_fault page_fault [exception RIP: ocfs2_block_group_find_clear_bits+316] ocfs2_block_group_find_clear_bits [ocfs2] ocfs2_cluster_group_search [ocfs2] ocfs2_search_chain [ocfs2] ocfs2_claim_suballoc_bits [ocfs2] __ocfs2_claim_clusters [ocfs2] ocfs2_claim_clusters [ocfs2] ocfs2_local_alloc_slide_window [ocfs2] ocfs2_reserve_local_alloc_bits [ocfs2] ocfs2_reserve_clusters_with_limit [ocfs2] ocfs2_reserve_clusters [ocfs2] ocfs2_lock_refcount_allocators [ocfs2] ocfs2_make_clusters_writable [ocfs2] ocfs2_replace_cow [ocfs2] ocfs2_refcount_cow [ocfs2] ocfs2_file_write_iter [ocfs2] lo_rw_aio loop_queue_work kthread_worker_fn kthread ret_from_fork 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.ananthakrishna@xxxxxxxxxx Signed-off-by: Gautham Ananthakrishna <gautham.ananthakrishna@xxxxxxxxxx> Reviewed-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> Cc: <rajesh.sivaramasubramaniom@xxxxxxxxxx> Cc: Mark Fasheh <mark@xxxxxxxxxx> Cc: Joel Becker <jlbec@xxxxxxxxxxxx> Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx> Cc: Changwei Ge <gechangwei@xxxxxxx> Cc: Gang He <ghe@xxxxxxxx> Cc: Jun Piao <piaojun@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ocfs2/suballoc.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) --- a/fs/ocfs2/suballoc.c +++ b/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; } Patches currently in stable-queue which might be from gautham.ananthakrishna@xxxxxxxxxx are queue-5.14/ocfs2-fix-race-between-searching-chunks-and-release-journal_head-from-buffer_head.patch