• Dmitry Monakhov's avatar
    ext4: Fix potential quota deadlock · d21cd8f1
    Dmitry Monakhov authored
    We have to delay vfs_dq_claim_space() until allocation context destruction.
    Currently we have following call-trace:
    ext4_mb_new_blocks()
      /* task is already holding ac->alloc_semp */
     ->ext4_mb_mark_diskspace_used
        ->vfs_dq_claim_space()  /*  acquire dqptr_sem here. Possible deadlock */
     ->ext4_mb_release_context() /* drop ac->alloc_semp here */
    
    Let's move quota claiming to ext4_da_update_reserve_space()
    
     =======================================================
     [ INFO: possible circular locking dependency detected ]
     2.6.32-rc7 #18
     -------------------------------------------------------
     write-truncate-/3465 is trying to acquire lock:
      (&s->s_dquot.dqptr_sem){++++..}, at: [<c025e73b>] dquot_claim_space+0x3b/0x1b0
    
     but task is already holding lock:
      (&meta_group_info[i]->alloc_sem){++++..}, at: [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370
    
     which lock already depends on the new lock.
    
     the existing dependency chain (in reverse order) is:
    
     -> #3 (&meta_group_info[i]->alloc_sem){++++..}:
            [<c017d04b>] __lock_acquire+0xd7b/0x1260
            [<c017d5ea>] lock_acquire+0xba/0xd0
            [<c0527191>] down_read+0x51/0x90
            [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370
            [<c02d0c1c>] ext4_mb_free_blocks+0x46c/0x870
            [<c029c9d3>] ext4_free_blocks+0x73/0x130
            [<c02c8cfc>] ext4_ext_truncate+0x76c/0x8d0
            [<c02a8087>] ext4_truncate+0x187/0x5e0
            [<c01e0f7b>] vmtruncate+0x6b/0x70
            [<c022ec02>] inode_setattr+0x62/0x190
            [<c02a2d7a>] ext4_setattr+0x25a/0x370
            [<c022ee81>] notify_change+0x151/0x340
            [<c021349d>] do_truncate+0x6d/0xa0
            [<c0221034>] may_open+0x1d4/0x200
            [<c022412b>] do_filp_open+0x1eb/0x910
            [<c021244d>] do_sys_open+0x6d/0x140
            [<c021258e>] sys_open+0x2e/0x40
            [<c0103100>] sysenter_do_call+0x12/0x32
    
     -> #2 (&ei->i_data_sem){++++..}:
            [<c017d04b>] __lock_acquire+0xd7b/0x1260
            [<c017d5ea>] lock_acquire+0xba/0xd0
            [<c0527191>] down_read+0x51/0x90
            [<c02a5787>] ext4_get_blocks+0x47/0x450
            [<c02a74c1>] ext4_getblk+0x61/0x1d0
            [<c02a7a7f>] ext4_bread+0x1f/0xa0
            [<c02bcddc>] ext4_quota_write+0x12c/0x310
            [<c0262d23>] qtree_write_dquot+0x93/0x120
            [<c0261708>] v2_write_dquot+0x28/0x30
            [<c025d3fb>] dquot_commit+0xab/0xf0
            [<c02be977>] ext4_write_dquot+0x77/0x90
            [<c02be9bf>] ext4_mark_dquot_dirty+0x2f/0x50
            [<c025e321>] dquot_alloc_inode+0x101/0x180
            [<c029fec2>] ext4_new_inode+0x602/0xf00
            [<c02ad789>] ext4_create+0x89/0x150
            [<c0221ff2>] vfs_create+0xa2/0xc0
            [<c02246e7>] do_filp_open+0x7a7/0x910
            [<c021244d>] do_sys_open+0x6d/0x140
            [<c021258e>] sys_open+0x2e/0x40
            [<c0103100>] sysenter_do_call+0x12/0x32
    
     -> #1 (&sb->s_type->i_mutex_key#7/4){+.+...}:
            [<c017d04b>] __lock_acquire+0xd7b/0x1260
            [<c017d5ea>] lock_acquire+0xba/0xd0
            [<c0526505>] mutex_lock_nested+0x65/0x2d0
            [<c0260c9d>] vfs_load_quota_inode+0x4bd/0x5a0
            [<c02610af>] vfs_quota_on_path+0x5f/0x70
            [<c02bc812>] ext4_quota_on+0x112/0x190
            [<c026345a>] sys_quotactl+0x44a/0x8a0
            [<c0103100>] sysenter_do_call+0x12/0x32
    
     -> #0 (&s->s_dquot.dqptr_sem){++++..}:
            [<c017d361>] __lock_acquire+0x1091/0x1260
            [<c017d5ea>] lock_acquire+0xba/0xd0
            [<c0527191>] down_read+0x51/0x90
            [<c025e73b>] dquot_claim_space+0x3b/0x1b0
            [<c02cb95f>] ext4_mb_mark_diskspace_used+0x36f/0x380
            [<c02d210a>] ext4_mb_new_blocks+0x34a/0x530
            [<c02c83fb>] ext4_ext_get_blocks+0x122b/0x13c0
            [<c02a5966>] ext4_get_blocks+0x226/0x450
            [<c02a5ff3>] mpage_da_map_blocks+0xc3/0xaa0
            [<c02a6ed6>] ext4_da_writepages+0x506/0x790
            [<c01de272>] do_writepages+0x22/0x50
            [<c01d766d>] __filemap_fdatawrite_range+0x6d/0x80
            [<c01d7b9b>] filemap_flush+0x2b/0x30
            [<c02a40ac>] ext4_alloc_da_blocks+0x5c/0x60
            [<c029e595>] ext4_release_file+0x75/0xb0
            [<c0216b59>] __fput+0xf9/0x210
            [<c0216c97>] fput+0x27/0x30
            [<c02122dc>] filp_close+0x4c/0x80
            [<c014510e>] put_files_struct+0x6e/0xd0
            [<c01451b7>] exit_files+0x47/0x60
            [<c0146a24>] do_exit+0x144/0x710
            [<c0147028>] do_group_exit+0x38/0xa0
            [<c0159abc>] get_signal_to_deliver+0x2ac/0x410
            [<c0102849>] do_notify_resume+0xb9/0x890
            [<c01032d2>] work_notifysig+0x13/0x21
    
     other info that might help us debug this:
    
     3 locks held by write-truncate-/3465:
      #0:  (jbd2_handle){+.+...}, at: [<c02e1f8f>] start_this_handle+0x38f/0x5c0
      #1:  (&ei->i_data_sem){++++..}, at: [<c02a57f6>] ext4_get_blocks+0xb6/0x450
      #2:  (&meta_group_info[i]->alloc_sem){++++..}, at: [<c02ce962>] ext4_mb_load_buddy+0xb2/0x370
    
     stack backtrace:
     Pid: 3465, comm: write-truncate- Not tainted 2.6.32-rc7 #18
     Call Trace:
      [<c0524cb3>] ? printk+0x1d/0x22
      [<c017ac9a>] print_circular_bug+0xca/0xd0
      [<c017d361>] __lock_acquire+0x1091/0x1260
      [<c016bca2>] ? sched_clock_local+0xd2/0x170
      [<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
      [<c017d5ea>] lock_acquire+0xba/0xd0
      [<c025e73b>] ? dquot_claim_space+0x3b/0x1b0
      [<c0527191>] down_read+0x51/0x90
      [<c025e73b>] ? dquot_claim_space+0x3b/0x1b0
      [<c025e73b>] dquot_claim_space+0x3b/0x1b0
      [<c02cb95f>] ext4_mb_mark_diskspace_used+0x36f/0x380
      [<c02d210a>] ext4_mb_new_blocks+0x34a/0x530
      [<c02c601d>] ? ext4_ext_find_extent+0x25d/0x280
      [<c02c83fb>] ext4_ext_get_blocks+0x122b/0x13c0
      [<c016bca2>] ? sched_clock_local+0xd2/0x170
      [<c016be60>] ? sched_clock_cpu+0x120/0x160
      [<c016beef>] ? cpu_clock+0x4f/0x60
      [<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
      [<c052712c>] ? down_write+0x8c/0xa0
      [<c02a5966>] ext4_get_blocks+0x226/0x450
      [<c016be60>] ? sched_clock_cpu+0x120/0x160
      [<c016beef>] ? cpu_clock+0x4f/0x60
      [<c017908b>] ? trace_hardirqs_off+0xb/0x10
      [<c02a5ff3>] mpage_da_map_blocks+0xc3/0xaa0
      [<c01d69cc>] ? find_get_pages_tag+0x16c/0x180
      [<c01d6860>] ? find_get_pages_tag+0x0/0x180
      [<c02a73bd>] ? __mpage_da_writepage+0x16d/0x1a0
      [<c01dfc4e>] ? pagevec_lookup_tag+0x2e/0x40
      [<c01ddf1b>] ? write_cache_pages+0xdb/0x3d0
      [<c02a7250>] ? __mpage_da_writepage+0x0/0x1a0
      [<c02a6ed6>] ext4_da_writepages+0x506/0x790
      [<c016beef>] ? cpu_clock+0x4f/0x60
      [<c016bca2>] ? sched_clock_local+0xd2/0x170
      [<c016be60>] ? sched_clock_cpu+0x120/0x160
      [<c016be60>] ? sched_clock_cpu+0x120/0x160
      [<c02a69d0>] ? ext4_da_writepages+0x0/0x790
      [<c01de272>] do_writepages+0x22/0x50
      [<c01d766d>] __filemap_fdatawrite_range+0x6d/0x80
      [<c01d7b9b>] filemap_flush+0x2b/0x30
      [<c02a40ac>] ext4_alloc_da_blocks+0x5c/0x60
      [<c029e595>] ext4_release_file+0x75/0xb0
      [<c0216b59>] __fput+0xf9/0x210
      [<c0216c97>] fput+0x27/0x30
      [<c02122dc>] filp_close+0x4c/0x80
      [<c014510e>] put_files_struct+0x6e/0xd0
      [<c01451b7>] exit_files+0x47/0x60
      [<c0146a24>] do_exit+0x144/0x710
      [<c017b163>] ? lock_release_holdtime+0x33/0x210
      [<c0528137>] ? _spin_unlock_irq+0x27/0x30
      [<c0147028>] do_group_exit+0x38/0xa0
      [<c017babb>] ? trace_hardirqs_on+0xb/0x10
      [<c0159abc>] get_signal_to_deliver+0x2ac/0x410
      [<c0102849>] do_notify_resume+0xb9/0x890
      [<c0178fd0>] ? trace_hardirqs_off_caller+0x20/0xd0
      [<c017b163>] ? lock_release_holdtime+0x33/0x210
      [<c0165b50>] ? autoremove_wake_function+0x0/0x50
      [<c017ba54>] ? trace_hardirqs_on_caller+0x134/0x190
      [<c017babb>] ? trace_hardirqs_on+0xb/0x10
      [<c0300ba4>] ? security_file_permission+0x14/0x20
      [<c0215761>] ? vfs_write+0x131/0x190
      [<c0214f50>] ? do_sync_write+0x0/0x120
      [<c0103115>] ? sysenter_do_call+0x27/0x32
      [<c01032d2>] work_notifysig+0x13/0x21
    
    CC: Theodore Ts'o <tytso@mit.edu>
    Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
    Signed-off-by: default avatarJan Kara <jack@suse.cz>
    d21cd8f1
mballoc.c 126 KB