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authorTheodore Ts'o <tytso@mit.edu>2009-12-09 21:30:02 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2009-12-14 09:45:28 -0800
commitabb247066f9769e90df87ab65e5c2bb4dbdb529c (patch)
tree068f5b752404f6032161788f42ac3f92d2b1ea07
parent0fd023ecf102ab0bd070d5affd73b18e6704ff0f (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.c4
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;