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From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: Dave Hansen <dave.hansen@intel.com>,
	linux-mm@kvack.org, akpm@linux-foundation.org,
	linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org
Cc: pavel.tatashin@microsoft.com, mhocko@suse.com,
	dave.jiang@intel.com, jglisse@redhat.com,
	rppt@linux.vnet.ibm.com, dan.j.williams@intel.com,
	logang@deltatee.com, mingo@kernel.org,
	kirill.shutemov@linux.intel.com
Subject: Re: [PATCH v5 2/4] mm: Provide kernel parameter to allow disabling page init poisoning
Date: Tue, 25 Sep 2018 13:38:43 -0700	[thread overview]
Message-ID: <8faf3acc-e47e-8ef9-a1a0-c0d6ebfafa1e@linux.intel.com> (raw)
In-Reply-To: <13285e05-fb90-b948-6f96-777f94079657@intel.com>



On 9/25/2018 1:26 PM, Dave Hansen wrote:
> On 09/25/2018 01:20 PM, 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
> 
> Can we have vm_debug=off for turning things off, please?  That seems to
> be pretty standard.

No. The simple reason for that is that you had requested this work like 
the slub_debug. If we are going to do that then each individual letter 
represents a feature. That is why the "-" represents off. We cannot have 
letters represent flags, and letters put together into words. For 
example slub_debug=OFF would turn on sanity checks and turn off 
debugging for caches that would have causes higher minimum slab orders.

Either I can do this as a single parameter that supports on/off 
semantics, or I can support it as a slub_debug type parameter that does 
flags based on the input options. I would rather not muddy things by 
trying to do both.

> Also, we need to document the defaults.  I think the default is "all
> debug options are enabled", but it would be nice to document that.

In the description I call out "All options are enabled by default, and 
this interface is meant to allow for selectively enabling or disabling".



  reply	other threads:[~2018-09-25 20:49 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 [this message]
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
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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