f2fs F2FS_IOC_SHUTDOWN hang issue

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Jaegeuk:

We encounter a deadlock issue when Android is going to poweroff.
Please help check.

When unmounting of  f2fs partition fail in Android poweroff procedure, init thread (pid = 1) invoke F2FS_IOC_SHUTDOWN  ioctl with arg F2FS_GOING_DOWN_FULLSYNC.
This ioctl cause down_write of a semaphore in the following call sequence:
        f2fs_ioc_shutdown() --> freeze_bdev() --> freeze_super() --> sb_wait_write(sb, SB_FREEZE_FS) --> ... ->percpu_down_write().

f2fs_ioc_shutdown() will later invoke f2fs_stop_discard_thread() and wait for stopping of f2fs_discard thread in the following call sequence:
        f2fs_ioc_shutdown() -->f2fs_stop_discard_thread() -->kthread_stop(discard_thread) --> wait_for_completion().
That is, init thread go sleep with a write semaphore.

f2fs_discard thread is then waken up to process f2fs discard.
However, f2fs_discard threshold may then hang because failing to get the semaphore aleady obtained by the slept init thread: 
        issue_discard_thread() --> sb_start_intwrite() -->sb_start_write(sb, SB_FREEZE_FS) --> percpu_down_read()

Light




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [NTFS 3]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [NTFS 3]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux