On Wed, Aug 08 2018 at 2:40am -0400, xiao jin <[email protected]> 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 <[email protected]> > --- > drivers/md/dm-bufio.c | 4 ++-- > drivers/md/dm-verity-target.c | 2 +- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c > index dc385b7..3b7ca5e 100644 > --- a/drivers/md/dm-bufio.c > +++ b/drivers/md/dm-bufio.c > @@ -841,7 +841,7 @@ static struct dm_buffer > *__alloc_buffer_wait_no_callback(struct dm_bufio_client > tried_noio_alloc = true; > } > > - if (!list_empty(&c->reserved_buffers)) { > + if (!c->need_reserved_buffers) { > b = list_entry(c->reserved_buffers.next, > struct dm_buffer, lru_list); > list_del(&b->lru_list); > @@ -1701,7 +1701,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct > block_device *bdev, unsign > goto bad; > } > > - while (c->need_reserved_buffers) { > + if (list_empty(&c->reserved_buffers)) { > struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL); > > if (!b) { Point was to allocate N buffers (as accounted in c->need_reserved_buffers). This change just allocates a single one. Why? Your header isn't clear on this at all. > diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c > index 12decdbd7..40c66fc 100644 > --- a/drivers/md/dm-verity-target.c > +++ b/drivers/md/dm-verity-target.c > @@ -1107,7 +1107,7 @@ static int verity_ctr(struct dm_target *ti, unsigned > argc, char **argv) > v->hash_blocks = hash_position; > > v->bufio = dm_bufio_client_create(v->hash_dev->bdev, > - 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), > + 1 << v->hash_dev_block_bits, 2, sizeof(struct buffer_aux), > dm_bufio_alloc_callback, NULL); > if (IS_ERR(v->bufio)) { > ti->error = "Cannot initialize dm-bufio"; > -- > 2.7.4 > > -- > dm-devel mailing list > [email protected] > https://www.redhat.com/mailman/listinfo/dm-devel It isn't at all clear from my initial review that what you're doing makes any sense. Seems like you're just papering over bufio's use of !__virt_addr_valid() memory in unintuitive ways. Mikulas, can you see a better way forward? Mike -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
