Messages in this thread | | | From | Michael Buesch <> | Subject | Re: Oops when using growisofs | Date | Tue, 24 Jun 2008 20:39:18 +0200 |
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On Tuesday 24 June 2008 19:28:12 Jan Kara wrote: > > On Mon, 23 Jun 2008 00:28:20 +0200 Michael Buesch <mb@bu3sch.de> wrote: > > > > > On Monday 23 June 2008 00:05:51 Michael Buesch wrote: > > > > > Note: r9 and r3 are both NULL pointers. r3 is the value returned from alloc_page_buffers. > > > > > R9 is a copy of that, which gets accessed. > > > > > > > > Hm, yeah. I looked at that code already, but I can't see how it could return > > > > a NULL pointer. > > > > > > Well, actually, it can return a NULL pointer. > > > > > > 928 head = NULL; > > > 929 offset = PAGE_SIZE; > > > 930 while ((offset -= size) >= 0) { > > > ... > > > 949 } > > > 950 return head; > > > > > > So if size, which is a passed in as parameter, is > PAGE_SIZE it will return NULL. > > > > > > The size parameter is calculated by doing > > > blocksize = 1 << inode->i_blkbits; > > > in an earlier function in the callchain. > > > > Yes, that's a more likely scenario. isofs has a history of passing > > garbage into the VFS. > > > > > So, well. I dunno what i_blkbits is. There's no docs in struct inode. > > > > It's log2 of the filesystem blocksize. It'd be interesting to work out > > what value isofs is setting it to, and why. > Well, yes, that looks as a reason at the first sight. But what I don't > get is, how can isofs possibly set such a blocksize when it uses > sb_set_blocksize() which checks whether blocksize isn't larger than page > size... So it must be something less obvious. > bd_set_size() can possibly set blocksize larger than PAGE_SIZE and > it's called from do_open() but it uses bdev_hardsect_size() and that > shouldn't be larger than PAGE_SIZE either (at least drivers seem to take > care of this). > I have seen one more report of this Oops for SLES10 kernel and also in that > case an IO error happened so probably that is a trigger... But so far I > don't get the details.
Yeah the IO error is the trigger. I noticed that it had obvious troubles accessing the DVD that was in the drive. It sweeped over it for several seconds, then hung the system for 2 or 3 seconds and then oopsed. But after that everything continued to work as usual. (Except kded of course)
-- Greetings Michael.
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