diff options
author | Theodore Ts'o <tytso@mit.edu> | 2009-12-09 21:30:02 -0500 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-12-14 09:45:28 -0800 |
commit | abb247066f9769e90df87ab65e5c2bb4dbdb529c (patch) | |
tree | 068f5b752404f6032161788f42ac3f92d2b1ea07 | |
parent | 0fd023ecf102ab0bd070d5affd73b18e6704ff0f (diff) |
ext4: Fix potential fiemap deadlock (mmap_sem vs. i_data_sem)
(cherry picked from commit fab3a549e204172236779f502eccb4f9bf0dc87d)
Fix the following potential circular locking dependency between
mm->mmap_sem and ei->i_data_sem:
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.32-04115-gec044c5 #37
-------------------------------------------------------
ureadahead/1855 is trying to acquire lock:
(&mm->mmap_sem){++++++}, at: [<ffffffff81107224>] might_fault+0x5c/0xac
but task is already holding lock:
(&ei->i_data_sem){++++..}, at: [<ffffffff811be1fd>] ext4_fiemap+0x11b/0x159
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&ei->i_data_sem){++++..}:
[<ffffffff81099bfa>] __lock_acquire+0xb67/0xd0f
[<ffffffff81099e7e>] lock_acquire+0xdc/0x102
[<ffffffff81516633>] down_read+0x51/0x84
[<ffffffff811a2414>] ext4_get_blocks+0x50/0x2a5
[<ffffffff811a3453>] ext4_get_block+0xab/0xef
[<ffffffff81154f39>] do_mpage_readpage+0x198/0x48d
[<ffffffff81155360>] mpage_readpages+0xd0/0x114
[<ffffffff811a104b>] ext4_readpages+0x1d/0x1f
[<ffffffff810f8644>] __do_page_cache_readahead+0x12f/0x1bc
[<ffffffff810f86f2>] ra_submit+0x21/0x25
[<ffffffff810f0cfd>] filemap_fault+0x19f/0x32c
[<ffffffff81107b97>] __do_fault+0x55/0x3a2
[<ffffffff81109db0>] handle_mm_fault+0x327/0x734
[<ffffffff8151aaa9>] do_page_fault+0x292/0x2aa
[<ffffffff81518205>] page_fault+0x25/0x30
[<ffffffff812a34d8>] clear_user+0x38/0x3c
[<ffffffff81167e16>] padzero+0x20/0x31
[<ffffffff81168b47>] load_elf_binary+0x8bc/0x17ed
[<ffffffff81130e95>] search_binary_handler+0xc2/0x259
[<ffffffff81166d64>] load_script+0x1b8/0x1cc
[<ffffffff81130e95>] search_binary_handler+0xc2/0x259
[<ffffffff8113255f>] do_execve+0x1ce/0x2cf
[<ffffffff81027494>] sys_execve+0x43/0x5a
[<ffffffff8102918a>] stub_execve+0x6a/0xc0
-> #0 (&mm->mmap_sem){++++++}:
[<ffffffff81099aa4>] __lock_acquire+0xa11/0xd0f
[<ffffffff81099e7e>] lock_acquire+0xdc/0x102
[<ffffffff81107251>] might_fault+0x89/0xac
[<ffffffff81139382>] fiemap_fill_next_extent+0x95/0xda
[<ffffffff811bcb43>] ext4_ext_fiemap_cb+0x138/0x157
[<ffffffff811be069>] ext4_ext_walk_space+0x178/0x1f1
[<ffffffff811be21e>] ext4_fiemap+0x13c/0x159
[<ffffffff811390e6>] do_vfs_ioctl+0x348/0x4d6
[<ffffffff811392ca>] sys_ioctl+0x56/0x79
[<ffffffff81028cb2>] system_call_fastpath+0x16/0x1b
other info that might help us debug this:
1 lock held by ureadahead/1855:
#0: (&ei->i_data_sem){++++..}, at: [<ffffffff811be1fd>] ext4_fiemap+0x11b/0x159
stack backtrace:
Pid: 1855, comm: ureadahead Not tainted 2.6.32-04115-gec044c5 #37
Call Trace:
[<ffffffff81098c70>] print_circular_bug+0xa8/0xb7
[<ffffffff81099aa4>] __lock_acquire+0xa11/0xd0f
[<ffffffff8102f229>] ? sched_clock+0x9/0xd
[<ffffffff81099e7e>] lock_acquire+0xdc/0x102
[<ffffffff81107224>] ? might_fault+0x5c/0xac
[<ffffffff81107251>] might_fault+0x89/0xac
[<ffffffff81107224>] ? might_fault+0x5c/0xac
[<ffffffff81124b44>] ? __kmalloc+0x13b/0x18c
[<ffffffff81139382>] fiemap_fill_next_extent+0x95/0xda
[<ffffffff811bcb43>] ext4_ext_fiemap_cb+0x138/0x157
[<ffffffff811bca0b>] ? ext4_ext_fiemap_cb+0x0/0x157
[<ffffffff811be069>] ext4_ext_walk_space+0x178/0x1f1
[<ffffffff811be21e>] ext4_fiemap+0x13c/0x159
[<ffffffff81107224>] ? might_fault+0x5c/0xac
[<ffffffff811390e6>] do_vfs_ioctl+0x348/0x4d6
[<ffffffff8129f6d0>] ? __up_read+0x8d/0x95
[<ffffffff81517fb5>] ? retint_swapgs+0x13/0x1b
[<ffffffff811392ca>] sys_ioctl+0x56/0x79
[<ffffffff81028cb2>] system_call_fastpath+0x16/0x1b
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r-- | fs/ext4/extents.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 43c04ff653c6..8b8bae4c0cf4 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1761,7 +1761,9 @@ int ext4_ext_walk_space(struct inode *inode, ext4_lblk_t block, while (block < last && block != EXT_MAX_BLOCK) { num = last - block; /* find extent for this block */ + down_read(&EXT4_I(inode)->i_data_sem); path = ext4_ext_find_extent(inode, block, path); + up_read(&EXT4_I(inode)->i_data_sem); if (IS_ERR(path)) { err = PTR_ERR(path); path = NULL; @@ -3730,10 +3732,8 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, * Walk the extent tree gathering extent information. * ext4_ext_fiemap_cb will push extents back to user. */ - down_read(&EXT4_I(inode)->i_data_sem); error = ext4_ext_walk_space(inode, start_blk, len_blks, ext4_ext_fiemap_cb, fieinfo); - up_read(&EXT4_I(inode)->i_data_sem); } return error; |