Messages in this thread | | | Date | Wed, 25 Apr 2007 19:53:35 +0200 | From | Jens Axboe <> | Subject | Re: [00/17] Large Blocksize Support V3 |
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On Wed, Apr 25 2007, Christoph Lameter wrote: > On Wed, 25 Apr 2007, Jens Axboe wrote: > > > I need this patch to actually boot the thing, or it bombs with a NULL > > deref in page_cache_size(). > > Yeah on 32 bit which I disabled....
Yep, on the grounds that devices may not cover the full address space. On my box they do.
> > It then boots, doing a little test with 8kb ext2 quickly dies though: > > > > BUG: unable to handle kernel NULL pointer dereference at virtual address > > > EIP: [<d8149519>] 0xd8149519 SS:ESP 0068:e9049d1c > > > > That's here: > > > > page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order, > > zonelist, ALLOC_WMARK_LOW|ALLOC_CPUSET); > > -> if (page) > > goto got_pg; > > Impossible. page is not dereferenced. Cannot cause a NULL pointer > deference.
Sure I know that, hence the oops happening there is likely fallout from something scribbling where it should not have.
> > which doesn't look healthy. Note that this is a 32-bit machine, I > > removed the 32-bit check (devices in this box are fine). > > > > > > --- fs/libfs.c~ 2007-04-25 13:30:50.000000000 +0200 > > +++ fs/libfs.c 2007-04-25 13:31:00.000000000 +0200 > > @@ -330,7 +330,7 @@ > > int simple_prepare_write(struct file *file, struct page *page, > > unsigned from, unsigned to) > > { > > - unsigned int page_size = page_cache_size(file->f_mapping); > > + unsigned int page_size = page_cache_size(page->mapping); > > We do a write operation on a file that has no mapping (and thus no radix > tree etc etc)? Is that legit?
Probably not.
-- Jens Axboe
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