From: Yu Kuai <yukuai3@xxxxxxxxxx> In journal_init_dev(), if super bdev is used as 'j_dev_bd', then blkdev_get_by_dev() is called with NULL holder, otherwise, holder will be journal. However, later in release_journal_dev(), blkdev_put() is called with journal unconditionally, cause following warning: WARNING: CPU: 1 PID: 5034 at block/bdev.c:617 bd_end_claim block/bdev.c:617 [inline] WARNING: CPU: 1 PID: 5034 at block/bdev.c:617 blkdev_put+0x562/0x8a0 block/bdev.c:901 RIP: 0010:blkdev_put+0x562/0x8a0 block/bdev.c:901 Call Trace: <TASK> release_journal_dev fs/reiserfs/journal.c:2592 [inline] free_journal_ram+0x421/0x5c0 fs/reiserfs/journal.c:1896 do_journal_release fs/reiserfs/journal.c:1960 [inline] journal_release+0x276/0x630 fs/reiserfs/journal.c:1971 reiserfs_put_super+0xe4/0x5c0 fs/reiserfs/super.c:616 generic_shutdown_super+0x158/0x480 fs/super.c:499 kill_block_super+0x64/0xb0 fs/super.c:1422 deactivate_locked_super+0x98/0x160 fs/super.c:330 deactivate_super+0xb1/0xd0 fs/super.c:361 cleanup_mnt+0x2ae/0x3d0 fs/namespace.c:1247 task_work_run+0x16f/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xadc/0x2a30 kernel/exit.c:874 do_group_exit+0xd4/0x2a0 kernel/exit.c:1024 __do_sys_exit_group kernel/exit.c:1035 [inline] __se_sys_exit_group kernel/exit.c:1033 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1033 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Fix this problem by passing in NULL holder in this case. Reported-by: syzbot+04625c80899f4555de39@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://syzkaller.appspot.com/bug?extid=04625c80899f4555de39 Fixes: 2736e8eeb0cc ("block: use the holder as indication for exclusive opens") Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> --- fs/reiserfs/journal.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c index 62beee3c62b6..479aa4a57602 100644 --- a/fs/reiserfs/journal.c +++ b/fs/reiserfs/journal.c @@ -2589,7 +2589,12 @@ static void release_journal_dev(struct super_block *super, struct reiserfs_journal *journal) { if (journal->j_dev_bd != NULL) { - blkdev_put(journal->j_dev_bd, journal); + void *holder = NULL; + + if (journal->j_dev_bd->bd_dev != super->s_dev) + holder = journal; + + blkdev_put(journal->j_dev_bd, holder); journal->j_dev_bd = NULL; } } -- 2.39.2
