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From: Dave Hansen <dave.hansen@intel.com>
To: Alexander Duyck <alexander.duyck@gmail.com>, mhocko@kernel.org
Cc: pavel.tatashin@microsoft.com, linux-nvdimm@lists.01.org,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	jglisse@redhat.com, Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 1/4] mm: Provide kernel parameter to allow disabling page init poisoning
Date: Wed, 12 Sep 2018 08:23:58 -0700	[thread overview]
Message-ID: <841e8101-40db-9ff2-f688-5f175d91fc31@intel.com> (raw)
In-Reply-To: <CAKgT0UdvhV7U5Zniq=KskXz2QsRP8C7ctr5=ZtJwYAVpBT-RHw@mail.gmail.com>

On 09/12/2018 07:49 AM, Alexander Duyck wrote:
>>> +     page_init_poison=       [KNL] Boot-time parameter changing the
>>> +                     state of poisoning of page structures during early
>>> +                     boot. Used to verify page metadata is not accessed
>>> +                     prior to initialization. Available with
>>> +                     CONFIG_DEBUG_VM=y.
>>> +                     off: turn off poisoning
>>> +                     on: turn on poisoning (default)
>>> +
>> what about the following wording or something along those lines
>>
>> Boot-time parameter to control struct page poisoning which is a
>> debugging feature to catch unitialized struct page access. This option
>> is available only for CONFIG_DEBUG_VM=y and it affects boot time
>> (especially on large systems). If there are no poisoning bugs reported
>> on the particular system and workload it should be safe to disable it to
>> speed up the boot time.
> That works for me. I will update it for the next release.

FWIW, I rather liked Dan's idea of wrapping this under
vm_debug=<something>.  We've got a zoo of boot options and it's really
hard to _remember_ what does what.  For this case, we're creating one
that's only available under a specific debug option and I think it makes
total sense to name the boot option accordingly.

For now, I think it makes total sense to do vm_debug=all/off.  If, in
the future, we get more options, we can do things like slab does and do
vm_debug=P (for Page poison) for this feature specifically.

	vm_debug =	[KNL] Available with CONFIG_DEBUG_VM=y.
			May slow down boot speed, especially on larger-
			memory systems when enabled.
			off: turn off all runtime VM debug features
			all: turn on all debug features (default)
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  reply	other threads:[~2018-09-12 15:25 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-10 23:43 [PATCH 0/4] Address issues slowing persistent memory initialization Alexander Duyck
2018-09-10 23:43 ` [PATCH 1/4] mm: Provide kernel parameter to allow disabling page init poisoning Alexander Duyck
2018-09-11  0:35   ` Alexander Duyck
2018-09-11 16:50   ` Dan Williams
2018-09-11 20:01     ` Alexander Duyck
2018-09-11 20:24       ` Dan Williams
2018-09-12 13:24   ` Pasha Tatashin
2018-09-12 14:10   ` Michal Hocko
2018-09-12 14:49     ` Alexander Duyck
2018-09-12 15:23       ` Dave Hansen [this message]
2018-09-12 16:36         ` Alexander Duyck
2018-09-12 16:43           ` Dave Hansen
2018-09-10 23:43 ` [PATCH 2/4] mm: Create non-atomic version of SetPageReserved for init use Alexander Duyck
2018-09-12 13:28   ` Pasha Tatashin
2018-09-10 23:43 ` [PATCH 3/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Alexander Duyck
2018-09-11  7:49   ` kbuild test robot
2018-09-11  7:54   ` kbuild test robot
2018-09-11 22:35   ` Dan Williams
2018-09-12  0:51     ` Alexander Duyck
2018-09-12  0:59       ` Dan Williams
2018-09-12 13:59   ` Pasha Tatashin
2018-09-12 15:48     ` Alexander Duyck
2018-09-12 15:54       ` Pasha Tatashin
2018-09-12 16:44         ` Alexander Duyck
2018-09-12 16:50       ` Dan Williams
2018-09-12 17:46         ` Pasha Tatashin
2018-09-12 19:11           ` Dan Williams
2018-09-10 23:44 ` [PATCH 4/4] nvdimm: Trigger the device probe on a cpu local to the device Alexander Duyck
2018-09-11  0:37   ` Alexander Duyck
2018-09-12  5:48   ` Dan Williams
2018-09-12 13:44   ` Pasha Tatashin

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