On Mon, 2005-02-28 at 16:51 +0100, Jens Axboe wrote: > On Mon, Feb 28 2005, Mark Haverkamp wrote: > > On Sat, 2005-02-26 at 13:39 +0100, Jens Axboe wrote: > > > On Fri, Feb 25 2005, Linus Torvalds wrote: > > > > > > > > > > > > On Fri, 25 Feb 2005, Andrew Morton wrote: > > > > > > > > > > It seems very weird for dm to be shoving NULL page*'s into the middle > > > > > of a > > > > > bio's bvec array, so your fix might end up being a workaround pending > > > > > a > > > > > closer look at what's going on in there. > > > > > > > > Yes. I don't see how this patch can be anything but bandaid to hide the > > > > real bug. Where do these "non-page" bvec's originate? > > > > > > Yep that's the fishy part, there should not be NULL pages in the middle > > > (or empty bios, for that matter) submitted for io. > > > > > > Mark, what was the bug that triggered you to write this patch? > > > > It happened when some pages of IO from a dm device were bounced. It > > looks to me when bio's are cloned in the dm code to split it for > > physical devices that only the pointers to pages that apply to that > > device are copied and th bi_idx is adjusted to point to the start, > > leaving some NULL pointers at the start of the bio_vec. > > This should fix it.
Wouldn't this potentially create bounce pages that will never be used? > > Signed-off-by: Jens Axboe <[EMAIL PROTECTED]> > > > ===== mm/highmem.c 1.55 vs edited ===== > --- 1.55/mm/highmem.c 2005-01-08 06:44:13 +01:00 > +++ edited/mm/highmem.c 2005-02-28 16:50:59 +01:00 > @@ -425,7 +425,7 @@ > * at least one page was bounced, fill in possible non-highmem > * pages > */ > - bio_for_each_segment(from, *bio_orig, i) { > + __bio_for_each_segment(from, *bio_orig, i) { > to = bio_iovec_idx(bio, i); > if (!to->bv_page) { > to->bv_page = from->bv_page; > -- Mark Haverkamp <[EMAIL PROTECTED]> - 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/