From: Michal Hocko <mhocko@kernel.org>
To: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: pavel.tatashin@microsoft.com, linux-nvdimm@lists.01.org,
dave.hansen@intel.com, linux-kernel@vger.kernel.org,
mingo@kernel.org, linux-mm@kvack.org, jglisse@redhat.com,
rppt@linux.vnet.ibm.com, akpm@linux-foundation.org,
kirill.shutemov@linux.intel.com
Subject: Re: [PATCH v5 2/4] mm: Provide kernel parameter to allow disabling page init poisoning
Date: Wed, 26 Sep 2018 17:39:21 +0200 [thread overview]
Message-ID: <20180926153921.GC6278@dhcp22.suse.cz> (raw)
In-Reply-To: <c57da51a-009a-9500-4dc5-1d9912e78abd@linux.intel.com>
On Wed 26-09-18 08:24:56, Alexander Duyck wrote:
> On 9/26/2018 12:38 AM, Michal Hocko wrote:
> > On Tue 25-09-18 13:20:12, Alexander Duyck wrote:
> > [...]
> > > + vm_debug[=options] [KNL] Available with CONFIG_DEBUG_VM=y.
> > > + May slow down system boot speed, especially when
> > > + enabled on systems with a large amount of memory.
> > > + All options are enabled by default, and this
> > > + interface is meant to allow for selectively
> > > + enabling or disabling specific virtual memory
> > > + debugging features.
> > > +
> > > + Available options are:
> > > + P Enable page structure init time poisoning
> > > + - Disable all of the above options
> >
> > I agree with Dave that this is confusing as hell. So what does vm_debug
> > (without any options means). I assume it's NOP and all debugging is
> > enabled and that is the default. What if I want to disable _only_ the
> > page struct poisoning. The weird lookcing `-' will disable all other
> > options that we might gather in the future.
>
> With no options it works just like slub_debug and enables all available
> options. So in our case it is a NOP since we wanted the debugging enabled by
> default.
But isn't slub_debug more about _adding_ debugging features? While you
want to effectively disbale some debugging features here? So if you want
to follow that pattern then it would be something like
vm_debug_disable=page_poisoning,$OTHER_FUTURE_DEBUG_OPTIONS
why would you want to enable something when CONFIG_DEBUG_VM=y just
enables everything?
> > Why cannot you simply go with [no]vm_page_poison[=on/off]?
>
> That is what I had to begin with, but Dave Hansen and Dan Williams suggested
> that I go with a slub_debug style interface so we could extend it in the
> future.
Please let's not over-engineer this. If you really need an umbrella
parameter then make a list of things to disable.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2018-09-26 15:39 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-25 20:18 [PATCH v5 0/4] Address issues slowing persistent memory initialization Alexander Duyck
2018-09-25 20:19 ` [PATCH v5 1/4] mm: Remove now defunct NO_BOOTMEM from depends list for deferred init Alexander Duyck
2018-09-25 21:05 ` Mike Rapoport
2018-09-25 20:20 ` [PATCH v5 2/4] mm: Provide kernel parameter to allow disabling page init poisoning Alexander Duyck
2018-09-25 20:26 ` Dave Hansen
2018-09-25 20:38 ` Alexander Duyck
2018-09-25 22:14 ` Dave Hansen
2018-09-25 22:27 ` Alexander Duyck
2018-09-26 7:38 ` Michal Hocko
2018-09-26 15:24 ` Alexander Duyck
2018-09-26 15:39 ` Michal Hocko [this message]
2018-09-26 15:41 ` Dave Hansen
2018-09-26 16:18 ` Alexander Duyck
2018-09-26 15:36 ` Dave Hansen
2018-09-26 22:36 ` Andrew Morton
2018-09-25 20:20 ` [PATCH v5 3/4] mm: Create non-atomic version of SetPageReserved for init use Alexander Duyck
2018-09-25 20:21 ` [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Alexander Duyck
2018-09-26 7:55 ` Michal Hocko
2018-09-26 18:25 ` Alexander Duyck
2018-09-26 18:52 ` Dan Williams
2018-09-27 11:20 ` Michal Hocko
2018-09-27 11:09 ` Michal Hocko
2018-09-27 12:25 ` Oscar Salvador
2018-09-27 13:13 ` Michal Hocko
2018-09-27 14:50 ` Oscar Salvador
2018-09-27 15:41 ` David Hildenbrand
2018-09-28 8:12 ` Oscar Salvador
2018-09-28 8:44 ` Oscar Salvador
2018-09-28 15:50 ` Dan Williams
2018-09-27 12:32 ` Oscar Salvador
2018-10-08 21:01 ` Dan Williams
2018-10-08 21:38 ` Alexander Duyck
2018-10-08 22:00 ` Dan Williams
2018-10-08 22:07 ` Alexander Duyck
2018-10-08 22:36 ` Alexander Duyck
2018-10-08 22:59 ` Dan Williams
2018-10-08 23:34 ` [mm PATCH] memremap: Fix reference count for pgmap in devm_memremap_pages Alexander Duyck
2018-10-09 0:20 ` Dan Williams
2018-10-09 17:00 ` [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Yi Zhang
2018-10-09 18:04 ` Dan Williams
2018-10-09 20:26 ` Alexander Duyck
2018-10-09 21:19 ` Dan Williams
2018-10-10 12:52 ` Yi Zhang
2018-10-10 15:27 ` Alexander Duyck
2018-10-11 8:17 ` Yi Zhang
2018-10-10 9:58 ` Michal Hocko
2018-10-10 16:39 ` Alexander Duyck
2018-10-10 17:24 ` Michal Hocko
2018-10-10 17:39 ` Alexander Duyck
2018-10-10 17:53 ` Michal Hocko
2018-10-10 18:13 ` Alexander Duyck
2018-10-10 18:52 ` Michal Hocko
2018-10-11 8:55 ` Michal Hocko
2018-10-11 17:38 ` Alexander Duyck
2018-10-11 18:22 ` Dan Williams
2018-10-17 7:52 ` Michal Hocko
2018-10-17 15:02 ` Alexander Duyck
2018-10-29 14:12 ` Michal Hocko
2018-10-29 15:59 ` Alexander Duyck
2018-10-29 16:35 ` Michal Hocko
2018-10-29 17:01 ` Alexander Duyck
2018-10-29 17:24 ` Michal Hocko
2018-10-29 17:34 ` Dan Williams
2018-10-29 17:45 ` Michal Hocko
2018-10-29 17:42 ` Alexander Duyck
2018-10-29 18:18 ` Michal Hocko
2018-10-29 19:59 ` Alexander Duyck
2018-10-30 6:29 ` Michal Hocko
2018-10-30 6:55 ` Dan Williams
2018-10-30 8:17 ` Michal Hocko
2018-10-30 15:57 ` Dan Williams
2018-10-30 8:05 ` Oscar Salvador
2018-10-29 15:49 ` Dan Williams
2018-10-29 15:56 ` Michal Hocko
2018-10-10 18:18 ` Dan Williams
2018-10-11 8:39 ` Yi Zhang
2018-10-11 15:38 ` Alexander Duyck
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