Russ Weight <[EMAIL PROTECTED]> wrote: > > On Fri, 2005-03-18 at 14:17 -0800, Andrew Morton wrote: > > Russ Weight <[EMAIL PROTECTED]> wrote: > > > > > > generic_forget_inode() is eventually called (within the context of > > > iput), the inode is placed on the unused list, and the inode_lock is > > > dropped. > > > > > > kswapd calls prune_icache(), locks the inode_lock, and pulls the same > > > inode off of the unused list. Upon completion, prune_icache() calls > > > dispose_list() for the inodes that it has collected. > > > > > > generic_forget_inode() calls write_inode_now(), which calls > > > __writeback_single_inode() which calls __sync_single_inode(). > > > __sync_single_inode() panics when attempting to move the inode onto the > > > unused list (the last call to list_move). This is due to the poison > > > values that were previously loaded into the next and prev list pointers > > > by list_del(). > > > > It's not clear what the actual bug is here. When you say that > > __sync_single_inode() panics over the list pointers, who was it that > > poisoned them? dispose_list()? > > > > Certainly isofs_fill_super() could trivially be rewritten to not do the > > iget()/iput() but we should be sure that that's really the bug. The inode > > lifetime management is rather messy, I'm afraid. > > The pointers are poisoned by dispose_list(). The race condition is > between prune_icache() and generic_forget_inode(). > > When I suggested that a change to isofs_fill_super() might be > considered, I was speculating that isofs_fill_super() might be creating > an unexpected state by doing something unconventional in its usage of > iget() and iput(). This is something I had not investigated. > > The problem is more likely in generic_forget_inode(). It releases the > inode_lock and then locks it again without doing anything to prevent the > inode from being stolen, and without checking to see if it has been > stolen. Likewise, write_inode_now() does not do any checks to see if the > inode has been stolen. >
I dunno. This is really fiddly code and does like to blow up in your face. I doubt if the problem is in such a well-trodden path as generic_forget_inode(). Perhaps isofs is breaking the rules by running iget() prior to setting MS_ACTIVE. (What rules, you ask? hah.) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
