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

Greg KH
2018-08-08T05:25:22Z

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@intel.com>
> ---
> 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.