linux-kernel - Re: [PATCH] mm: Free unused pages in kmalloc

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Message-ID: <c5f54ce3-dad6-a2aa-d32a-cc7620676b76@web.de>
Date:   Sun, 28 Jun 2020 13:17:59 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Long Li <lonuxli.64@...il.com>, linux-mm@...ck.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Pekka Enberg <penberg@...nel.org>
Subject: Re: [PATCH] mm: Free unused pages in kmalloc_order()

> kmalloc(1024, GFP_HIGHUSER) can allocate memory normally,
> kmalloc(64*1024, GFP_HIGHUSER) will cause a memory leak,

Would you like to explain the influence of the selected allocation size
in a different way?

> because alloc_pages returns highmem physical pages, but it cannot be directly
> converted into a virtual address and return NULL, the pages has not
> been released. Usually driver developers will not use the
> GFP_HIGHUSER flag to allocate memory in kmalloc, but I think this
> memory leak is not perfect, it is best to be fixed.

I suggest to improve this change description.

* Did you apply any special analysis tools?

* How do you think about to split the text into more sentences?

* Would you like to extend any software documentation?

> This is the first time I have posted a patch,

I find this information irrelevant for the proposed commit message.

> there may be something wrong.

There are usual risks to consider also for such software development.

Will it become helpful to add the tag “Fixes”?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?id=719fdd32921fb7e3208db8832d32ae1c2d68900f#n183

Regards,
Markus