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    SubjectRe: [PATCH v2 2/3] mm, page_owner: decouple freeing stack trace from debug_pagealloc
    On Tue, Oct 01, 2019 at 10:07:44AM +0200, Vlastimil Babka wrote:
    > On 10/1/19 1:49 AM, Qian Cai wrote:
    > >
    > >
    > >> On Sep 30, 2019, at 5:43 PM, Vlastimil Babka <vbabka@suse.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.
    >
    > They can do that and it was intention, yes. The extra parameter was
    > requested by Kirill, so I'll defer the answer to him :)

    DEBUG_PAGEALLOC is much more intrusive debug option. Not all architectures
    support it in an efficient way. Some require hibernation.

    I don't see a reason to tie these two option together.

    --
    Kirill A. Shutemov

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