lkml.org 
[lkml]   [2004]   [Aug]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] bio_uncopy_user mem leak
Hi Chris,

On Thu, Aug 19, 2004 at 09:51:34AM -0400, Chris Mason wrote:
> On Thu, 2004-08-19 at 07:07, Con Kolivas wrote:
> > Ok I just tested this patch discretely and indeed the memory leak goes
> > away but it still produces coasters so something is still amuck. Just as
> > a data point; burning DVDs and data cds is ok. Burning audio *and
> > videocds* is not.
>
> It might be the cold medicine talking, but I think we need something
> like this. gcc tested it for me, beyond that I make no promises....
>
> --- l/fs/bio.c.1 2004-08-19 09:36:13.596858736 -0400
> +++ l/fs/bio.c 2004-08-19 09:47:46.392537784 -0400
> @@ -454,6 +454,7 @@
> */
> if (!ret) {
> if (!write_to_vm) {
> + unsigned long p = uaddr;
> bio->bi_rw |= (1 << BIO_RW);
> /*
> * for a write, copy in data to kernel pages
> @@ -462,8 +463,9 @@
> bio_for_each_segment(bvec, bio, i) {
> char *addr = page_address(bvec->bv_page);
>
> - if (copy_from_user(addr, (char *) uaddr, bvec->bv_len))
> + if (copy_from_user(addr, (char *) p, bvec->bv_len))
> goto cleanup;
> + p += bvec->bv_len;
> }
> }
>

Hmm, that patch would make a lot of sense to me.

It matches the problem description; burning data CDs, we don't
use bounce buffers, so that does not use this code path. Here,
it looks like we copied the same userspace page again and again
into a multisegment BIO. Ouch!

Not yet tested either :-(

Regards,
--
Kurt Garloff, Director SUSE Labs, Novell Inc.
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2005-03-22 14:05    [from the cache]
©2003-2011 Jasper Spaans