linux-kernel - Re: [PATCH v2 2/3] mm, page_owner: decouple freeing stack trace from debug

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Message-Id: <731C4866-DF28-4C96-8EEE-5F22359501FE@lca.pw>
Date:   Mon, 30 Sep 2019 19:49:18 -0400
From:   Qian Cai <cai@....pw>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Matthew Wilcox <willy@...radead.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Michal Hocko <mhocko@...nel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Walter Wu <walter-zh.wu@...iatek.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: Re: [PATCH v2 2/3] mm, page_owner: decouple freeing stack trace from debug_pagealloc



> On Sep 30, 2019, at 5:43 PM, Vlastimil Babka <vbabka@...e.cz> wrote:
> 
> Well, my use case is shipping production kernels with CONFIG_PAGE_OWNER
> and CONFIG_DEBUG_PAGEALLOC enabled, and instructing users to boot-time
> enable only for troubleshooting a crash or memory leak, without a need
> to install a debug kernel. Things like static keys and page_ext
> allocations makes this possible without CPU and memory overhead when not
> boot-time enabled. I don't know too much about KASAN internals, but I
> assume it's not possible to use it that way on production kernels yet?

In that case, why can’t users just simply enable page_owner=on and debug_pagealloc=on for troubleshooting? The later makes the kernel slower, but I am not sure if it is worth optimization by adding a new parameter. There have already been quite a few MM-related kernel parameters that could tidy up a bit in the future.