Abstract:
We give the following extension of a theorem by Hardy and Littlewood. Suppose $f$ is a holomorphic function in the unit disk and $$
M_p(r,f)=\Bigl(\frac1{2\pi}\int_{-\pi}^\pi|f(re^{i\theta})|^pd\theta\Bigr)^{\frac1p}=O(\varphi(r)),\quad r\to1-0,
$$ where $\varphi$ is a monotone increasing function on $(0,1)$ and $$
\alpha_\varphi=\lim_{r\to1-0}\frac{\varphi'(r)(1-r)}{\varphi(r)}.
$$