linux-kernel - [RFC] does ioremap() cause memory leak?

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Date:   Thu, 21 Dec 2017 16:55:10 +0800
From:   Xishi Qiu <qiuxishi@...wei.com>
To:     Toshi Kani <toshi.kani@...com>, "H. Peter Anvin" <hpa@...or.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>
CC:     LKML <linux-kernel@...r.kernel.org>, Linux MM <linux-mm@...ck.org>,
        "Xishi Qiu" <qiuxishi@...wei.com>
Subject: [RFC] does ioremap() cause memory leak?

When we use iounmap() to free the mapping, it calls unmap_vmap_area() to clear page table,
but do not free the memory of page table, right?

So when use ioremap() to mapping another area(incluce the area before), it may use
large mapping(e.g. ioremap_pmd_enabled()), so the original page table memory(e.g. pte memory)
will be lost, it cause memory leak, right?

Thanks,
Xishi Qiu