Re: [Intel-gfx] [PATCH rdma-next v3 1/2] lib/scatterlist: Add support in dynamic allocation of SG table from pages

From: Maor Gottlieb <maorg@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>, Leon Romanovsky <leon@kernel.org>
Cc: linux-rdma@vger.kernel.org, intel-gfx@lists.freedesktop.org,
	Roland Scheidegger <sroland@vmware.com>,
	dri-devel@lists.freedesktop.org,
	Maor Gottlieb <maorg@mellanox.com>,
	David Airlie <airlied@linux.ie>,
	Doug Ledford <dledford@redhat.com>,
	VMware Graphics <linux-graphics-maintainer@vmware.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [Intel-gfx] [PATCH rdma-next v3 1/2] lib/scatterlist: Add support in dynamic allocation of SG table from pages
Date: Fri, 25 Sep 2020 15:18:09 +0300	[thread overview]
Message-ID: <65ca566b-7a5e-620f-13a4-c59eb836345a@nvidia.com> (raw)
In-Reply-To: <20200925115544.GY9475@nvidia.com>

On 9/25/2020 2:55 PM, Jason Gunthorpe wrote:
> On Fri, Sep 25, 2020 at 10:13:30AM +0300, Leon Romanovsky wrote:
>>>> diff --git a/tools/testing/scatterlist/main.c b/tools/testing/scatterlist/main.c
>>>> index 0a1464181226..4899359a31ac 100644
>>>> +++ b/tools/testing/scatterlist/main.c
>>>> @@ -55,14 +55,13 @@ int main(void)
>>>>    	for (i = 0, test = tests; test->expected_segments; test++, i++) {
>>>>    		struct page *pages[MAX_PAGES];
>>>>    		struct sg_table st;
>>>> -		int ret;
>>>> +		struct scatterlist *sg;
>>>>
>>>>    		set_pages(pages, test->pfn, test->num_pages);
>>>>
>>>> -		ret = __sg_alloc_table_from_pages(&st, pages, test->num_pages,
>>>> -						  0, test->size, test->max_seg,
>>>> -						  GFP_KERNEL);
>>>> -		assert(ret == test->alloc_ret);
>>>> +		sg = __sg_alloc_table_from_pages(&st, pages, test->num_pages, 0,
>>>> +				test->size, test->max_seg, NULL, 0, GFP_KERNEL);
>>>> +		assert(PTR_ERR_OR_ZERO(sg) == test->alloc_ret);
>>> Some test coverage for relatively complex code would be very welcomed. Since
>>> the testing framework is already there, even if it bit-rotted a bit, but
>>> shouldn't be hard to fix.
>>>
>>> A few tests to check append/grow works as expected, in terms of how the end
>>> table looks like given the initial state and some different page patterns
>>> added to it. And both crossing and not crossing into sg chaining scenarios.
>> This function is basic for all RDMA devices and we are pretty confident
>> that the old and new flows are tested thoroughly.
> Well, since 0-day is reporting that __i915_gem_userptr_alloc_pages is
> crashing on this, it probably does need some tests :\
>
> Jason

It is crashing in the regular old flow which already tested.
However, I will add more tests.
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