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Date:   Wed, 14 Sep 2022 09:26:51 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     "zhaoyang.huang" <zhaoyang.huang@unisoc.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Zhaoyang Huang <huangzhaoyang@gmail.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, ke.wang@unisoc.com
Subject: Re: [PATCH 2/2] mm: introduce __GFP_TRACKLEAK to track in-kernel
 allocation
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On Wed, Sep 14, 2022 at 11:37:01AM +0800, zhaoyang.huang wrote:
> ---
> v2: code update
> v3: update code and Documentation

This is really not good enough.  What changed?

The documentation is also not good enough.  It needs to mention:

 - This cannot be used for GFP_HIGHMEM allocations.
 - This cannot be used for pages which are mapped into userspace.

I also still want to see selftests.  order-0, order-N (with and without
__GFP_COMP).  What happens if you allocate an order-N page without
GFP_COMP, take an extra ref on the first page, call free_pages() and
then one of the recently-freed pages is allocated again while you still
have the reference on the first page?

I believe Andrew also suggested that 

if (PageTrackleak(page))

become always-false if the CONFIG option is disabled.

> +#ifdef CONFIG_HAVE_DEBUG_KMEMLEAK

This is the wrong CONFIG option, it should be CONFIG_DEBUG_KMEMLEAK.


Add to this the very real question of how useful is this, and I'm not
getting warm fuzzy feelings about where this patchset is heading.