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Subject: Re: [PATCH 10/28] mm: only allow page table mappings for built-in
 zsmalloc
To:     Matthew Wilcox <willy@infradead.org>,
        Peter Zijlstra <peterz@infradead.org>
Cc:     Christoph Hellwig <hch@lst.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, x86@kernel.org,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Laura Abbott <labbott@redhat.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Minchan Kim <minchan@kernel.org>,
        Nitin Gupta <ngupta@vflare.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
        linux-arch@vger.kernel.org, linux-mm@kvack.org,
        iommu@lists.linux-foundation.org,
        linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20200408115926.1467567-1-hch@lst.de>
 <20200408115926.1467567-11-hch@lst.de>
 <c0c86feb-b3d8-78f2-127f-71d682ffc51f@infradead.org>
 <20200408151203.GN20730@hirez.programming.kicks-ass.net>
 <20200408151519.GQ21484@bombadil.infradead.org>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <139a494a-f946-fd4b-4854-6ff625e4c24f@infradead.org>
Date:   Wed, 8 Apr 2020 08:36:56 -0700
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On 4/8/20 8:15 AM, Matthew Wilcox wrote:
> On Wed, Apr 08, 2020 at 05:12:03PM +0200, Peter Zijlstra wrote:
>> On Wed, Apr 08, 2020 at 08:01:00AM -0700, Randy Dunlap wrote:
>>> Hi,
>>>
>>> On 4/8/20 4:59 AM, Christoph Hellwig wrote:
>>>> diff --git a/mm/Kconfig b/mm/Kconfig
>>>> index 36949a9425b8..614cc786b519 100644
>>>> --- a/mm/Kconfig
>>>> +++ b/mm/Kconfig
>>>> @@ -702,7 +702,7 @@ config ZSMALLOC
>>>>  
>>>>  config ZSMALLOC_PGTABLE_MAPPING
>>>>  	bool "Use page table mapping to access object in zsmalloc"
>>>> -	depends on ZSMALLOC
>>>> +	depends on ZSMALLOC=y
>>>
>>> It's a bool so this shouldn't matter... not needed.
>>
>> My mm/Kconfig has:
>>
>> config ZSMALLOC
>> 	tristate "Memory allocator for compressed pages"
>> 	depends on MMU
>>
>> which I think means it can be modular, no?

ack. I misread it.

> Randy means that ZSMALLOC_PGTABLE_MAPPING is a bool, so I think hch's patch
> is wrong ... if ZSMALLOC is 'm' then ZSMALLOC_PGTABLE_MAPPING would become
> 'n' instead of 'y'.

sigh, I wish that I had meant that. :)

thanks.

-- 
~Randy