Re: [PATCH] dm-bufio: adjust the reserved buffer for dm-verify-target.

[xiaojin]

On 2018å08æ08æ 13:25, Greg KH wrote:
> On Wed, Aug 08, 2018 at 01:07:03PM +0800, xiao jin wrote:
> > We hit the BUG() report at include/linux/scatterlist.h:144!
> > The callback is as bellow:
> >    => verity_work
> >    => verity_hash_for_block
> >    => verity_verify_level
> >    => verity_hash
> >    => verity_hash_update
> >    => sg_init_one
> >    => sg_set_buf
> >
> > More debug shows the root cause. When creating dufio client it
> > uses the __vmalloc() to allocate the buffer data for the reserved
> > dm_buffer. The buffer that allocated by the __vmalloc() is invalid
> > according to the __virt_addr_valid().
> >
> > Mostly the reserved dm_buffer is not touched. But occasionally
> > it might fail to allocate the dm_buffer data when we try to
> > allocate in the __alloc_buffer_wait_no_callback(). Then it has
> > to take the reserved dm_buffer for usage. Finally it reports the
> > BUG() as virt_addr_valid() detects the buffer data address is invalid.
> >
> > The patch is to adjust the reserved buffer for dm-verity-target. We
> > allocated two dm_buffers into the reserved buffers list when creating
> > the buffer interface. The first dm_buffer in the reserved buffer list
> > is allocated by the __vmalloc(), it's not used after that. The second
> > dm_buffer in the reserved buffer list is allocated by the
> > __get_free_pages() which can be consumed after that.
> >
> > Signed-off-by: xiao jin <jin.xiao@xxxxxxxxx>
> > ---
> >   drivers/md/dm-bufio.c         | 4 ++--
> >   drivers/md/dm-verity-target.c | 2 +-
> >   2 files changed, 3 insertions(+), 3 deletions(-)
> <formletter>
>
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree.  Please read:
>      https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> for how to do this properly.
>
> </formletter>
Thanks, I will resend to review without the stable mail list.