• Q
    jbd2: fix data races at struct journal_head · 8d6725cc
    Qian Cai 提交于
    task #28557737
    
    [ Upstream commit 6c5d911249290f41f7b50b43344a7520605b1acb ]
    
    journal_head::b_transaction and journal_head::b_next_transaction could
    be accessed concurrently as noticed by KCSAN,
    
     LTP: starting fsync04
     /dev/zero: Can't open blockdev
     EXT4-fs (loop0): mounting ext3 file system using the ext4 subsystem
     EXT4-fs (loop0): mounted filesystem with ordered data mode. Opts: (null)
     ==================================================================
     BUG: KCSAN: data-race in __jbd2_journal_refile_buffer [jbd2] / jbd2_write_access_granted [jbd2]
    
     write to 0xffff99f9b1bd0e30 of 8 bytes by task 25721 on cpu 70:
      __jbd2_journal_refile_buffer+0xdd/0x210 [jbd2]
      __jbd2_journal_refile_buffer at fs/jbd2/transaction.c:2569
      jbd2_journal_commit_transaction+0x2d15/0x3f20 [jbd2]
      (inlined by) jbd2_journal_commit_transaction at fs/jbd2/commit.c:1034
      kjournald2+0x13b/0x450 [jbd2]
      kthread+0x1cd/0x1f0
      ret_from_fork+0x27/0x50
    
     read to 0xffff99f9b1bd0e30 of 8 bytes by task 25724 on cpu 68:
      jbd2_write_access_granted+0x1b2/0x250 [jbd2]
      jbd2_write_access_granted at fs/jbd2/transaction.c:1155
      jbd2_journal_get_write_access+0x2c/0x60 [jbd2]
      __ext4_journal_get_write_access+0x50/0x90 [ext4]
      ext4_mb_mark_diskspace_used+0x158/0x620 [ext4]
      ext4_mb_new_blocks+0x54f/0xca0 [ext4]
      ext4_ind_map_blocks+0xc79/0x1b40 [ext4]
      ext4_map_blocks+0x3b4/0x950 [ext4]
      _ext4_get_block+0xfc/0x270 [ext4]
      ext4_get_block+0x3b/0x50 [ext4]
      __block_write_begin_int+0x22e/0xae0
      __block_write_begin+0x39/0x50
      ext4_write_begin+0x388/0xb50 [ext4]
      generic_perform_write+0x15d/0x290
      ext4_buffered_write_iter+0x11f/0x210 [ext4]
      ext4_file_write_iter+0xce/0x9e0 [ext4]
      new_sync_write+0x29c/0x3b0
      __vfs_write+0x92/0xa0
      vfs_write+0x103/0x260
      ksys_write+0x9d/0x130
      __x64_sys_write+0x4c/0x60
      do_syscall_64+0x91/0xb05
      entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
     5 locks held by fsync04/25724:
      #0: ffff99f9911093f8 (sb_writers#13){.+.+}, at: vfs_write+0x21c/0x260
      #1: ffff99f9db4c0348 (&sb->s_type->i_mutex_key#15){+.+.}, at: ext4_buffered_write_iter+0x65/0x210 [ext4]
      #2: ffff99f5e7dfcf58 (jbd2_handle){++++}, at: start_this_handle+0x1c1/0x9d0 [jbd2]
      #3: ffff99f9db4c0168 (&ei->i_data_sem){++++}, at: ext4_map_blocks+0x176/0x950 [ext4]
      #4: ffffffff99086b40 (rcu_read_lock){....}, at: jbd2_write_access_granted+0x4e/0x250 [jbd2]
     irq event stamp: 1407125
     hardirqs last  enabled at (1407125): [<ffffffff980da9b7>] __find_get_block+0x107/0x790
     hardirqs last disabled at (1407124): [<ffffffff980da8f9>] __find_get_block+0x49/0x790
     softirqs last  enabled at (1405528): [<ffffffff98a0034c>] __do_softirq+0x34c/0x57c
     softirqs last disabled at (1405521): [<ffffffff97cc67a2>] irq_exit+0xa2/0xc0
    
     Reported by Kernel Concurrency Sanitizer on:
     CPU: 68 PID: 25724 Comm: fsync04 Tainted: G L 5.6.0-rc2-next-20200221+ #7
     Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
    
    The plain reads are outside of jh->b_state_lock critical section which result
    in data races. Fix them by adding pairs of READ|WRITE_ONCE().
    Reviewed-by: NJan Kara <jack@suse.cz>
    Signed-off-by: NQian Cai <cai@lca.pw>
    Link: https://lore.kernel.org/r/20200222043111.2227-1-cai@lca.pwSigned-off-by: NTheodore Ts'o <tytso@mit.edu>
    Signed-off-by: NSasha Levin <sashal@kernel.org>
    Signed-off-by: NJeffle Xu <jefflexu@linux.alibaba.com>
    Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
    8d6725cc
transaction.c 82.5 KB