Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH 10/28] mm: only allow page table mappings for built-in
 zsmalloc
To:     Christoph Hellwig <hch@lst.de>,
        Matthew Wilcox <willy@infradead.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        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>
 <20200408153602.GA28081@lst.de>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <ce1cb560-2670-c79d-48eb-e4dd423aecb0@infradead.org>
Date:   Wed, 8 Apr 2020 08:37:59 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.6.0
MIME-Version: 1.0
In-Reply-To: <20200408153602.GA28081@lst.de>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 4/8/20 8:36 AM, Christoph Hellwig wrote:
> On Wed, Apr 08, 2020 at 08:15:19AM -0700, Matthew Wilcox wrote:
>>>>>  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?
>>
>> 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'.
> 
> In Linus' tree you can select PGTABLE_MAPPING=y with ZSMALLOC=m,
> and that fits my understanding of the kbuild language.  With this
> patch I can't anymore.
> 

Makes sense. thanks.

-- 
~Randy