Messages in this thread | | | Date | Sun, 3 Jun 2007 10:28:40 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [PATCH 2/2] Fix possible leakage of blocks in UDF |
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[Andrew Morton - Sat, Jun 02, 2007 at 03:49:42PM -0700] | On Sun, 3 Jun 2007 00:01:46 +0400 Cyrill Gorcunov <gorcunov@gmail.com> wrote: | | > [Andrew Morton - Sat, Jun 02, 2007 at 12:16:16PM -0700] | > [...snip...] | > | | > | No, the problem is that the patch caused the kernel to take inode_lock | > | within the newly-added drop_inode(), btu drop_inode() is already called | > | under inode_lock. | > | | > | It has nothing to do with lock_kernel() and it has nothing to do with | > | sleeping. | > | | > | > Andrew, the only call that could leading to subseq. inode_lock lock | > is mark_inode_dirty() I guess (and that is snown by Eric's dump) | > but as I shown you in my dbg print without SMP it's OK. So | > is it SMP who lead to lock? How it depends on it? (I understand | > that is a stupid question for you but if you have time explain | > me this please ;) | > | | When CONFIG_SMP=n, spin_lock() is a no-op. (Except with CONFIG_PREEMPT=y, | in which case spin_lock() will disable kernel preemption on SMP and non-SMP | kernels) | | When CONFIG_SMP=y, spin_lock() really does take a lock. But if this thread | already holds this lock, we'll deadlock. |
Thanks, Andrew. So the reason that raises lock problem is the calling of mark_inode_dirty() inside drop_inode() (by indirection). And I see two way of solution:
- or check for inode->i_count at each mark_inode_dirty that being called after drop_inode
if (inode->i_count > 0) mark_inode_dirty()
- or wrap mark_inode_dirty as
udf_mark_inode_dirty() { if (inode->i_count > 0) mark_inode_dirty(); }
and replace all mark_inode_dirty -> udf_mark_inode_dirty
Your thoughts?
Cyrill
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