The problem is caused by this bit in af_alg_sendmsg():
/* use the existing memory in an allocated page */
if (ctx->merge) {
sgl = list_entry(ctx->tsgl_list.prev,
struct af_alg_tsgl, list);
sg = sgl->sg + sgl->cur - 1;
len = min_t(size_t, len,
PAGE_SIZE - sg->offset - sg->length);
err = memcpy_from_msg(page_address(sg_page(sg)) +
sg->offset + sg->length,
msg, len);
if (err)
goto unlock;
sg->length += len;
ctx->merge = (sg->offset + sg->length) &
(PAGE_SIZE - 1);
ctx->used += len;
copied += len;
size -= len;
continue;
}
it doesn't exist in the old af_alg_sendpage() code. It merges data supplied
by sendmsg() into the last page in the list if there's space. So we need a
flag to keep track of whether the last page is appendable-to or not.
David
