linux-kernel - Re: [PATCH] powerpc/nvram: Replace kmalloc with kzalloc in the error message

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Date:   Tue, 2 Jun 2020 07:01:29 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Liao Pingfang <liao.pingfang@....com.cn>,
        linuxppc-dev@...ts.ozlabs.org
Cc:     Allison Randal <allison@...utok.net>,
        Anton Vorontsov <anton@...msg.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Colin Cross <ccross@...roid.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kees Cook <keescook@...omium.org>,
        Paul Mackerras <paulus@...ba.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tony Luck <tony.luck@...el.com>,
        Wang Liang <wang.liang82@....com.cn>,
        Xue Zhihong <xue.zhihong@....com.cn>,
        Yi Wang <wang.yi59@....com.cn>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] powerpc/nvram: Replace kmalloc with kzalloc in the error
 message

>>> Please just remove the message instead, it's a tiny allocation that's
>>> unlikely to ever fail, and the caller will print an error anyway.
>>
>> How do you think about to take another look at a previous update suggestion
>> like the following?
>>
>> powerpc/nvram: Delete three error messages for a failed memory allocation
>> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/00845261-8528-d011-d3b8-e9355a231d3a@users.sourceforge.net/
>> https://lore.kernel.org/linuxppc-dev/00845261-8528-d011-d3b8-e9355a231d3a@users.sourceforge.net/
>> https://lore.kernel.org/patchwork/patch/752720/
>> https://lkml.org/lkml/2017/1/19/537
>
> That deleted the messages from nvram_scan_partitions(), but neither of
> the callers of nvram_scan_paritions() check its return value or print
> anything if it fails. So removing those messages would make those
> failures silent which is not what we want.

* How do you think about information like the following?
  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=f359287765c04711ff54fbd11645271d8e5ff763#n883
“…
These generic allocation functions all emit a stack dump on failure when used
without __GFP_NOWARN so there is no use in emitting an additional failure
message when NULL is returned.
…”

* Would you like to clarify software development concerns around
  the Linux allocation failure report any more?

Regards,
Markus