On Thu 05-07-18 14:17:19, Christopher Lameter wrote:
> On Wed, 4 Jul 2018, Jan Kara wrote:
>
> > > So this seems unsolvable without having the caller specify that it knows
> > > the
> > > page type, and that it is therefore safe to decrement
> > > page->dma_pinned_count.
> > > I was hoping I'd f
On Wed, 4 Jul 2018, Jan Kara wrote:
> > So this seems unsolvable without having the caller specify that it knows the
> > page type, and that it is therefore safe to decrement
> > page->dma_pinned_count.
> > I was hoping I'd found a way, but clearly I haven't. :)
>
> Well, I think the misconceptio
On Tue 03-07-18 10:36:05, John Hubbard wrote:
> On 07/03/2018 10:08 AM, Christopher Lameter wrote:
> > On Mon, 2 Jul 2018, John Hubbard wrote:
> >
> >>> If you establish a reference to a page then increase the page count. If
> >>> the reference is a dma pin action also then increase the pinned cou
On 07/03/2018 10:48 AM, Christopher Lameter wrote:
> On Tue, 3 Jul 2018, John Hubbard wrote:
>
>> The page->_refcount field is used normally, in addition to the
>> dma_pinned_count.
>> But the problem is that, unless the caller knows what kind of page it is,
>> the page->dma_pinned_count cannot b
On Tue, 3 Jul 2018, John Hubbard wrote:
> The page->_refcount field is used normally, in addition to the
> dma_pinned_count.
> But the problem is that, unless the caller knows what kind of page it is,
> the page->dma_pinned_count cannot be looked at, because it is unioned with
> page->lru.prev.
On 07/03/2018 10:08 AM, Christopher Lameter wrote:
> On Mon, 2 Jul 2018, John Hubbard wrote:
>
>>> If you establish a reference to a page then increase the page count. If
>>> the reference is a dma pin action also then increase the pinned count.
>>>
>>> That way you know how many of the references
On Mon, 2 Jul 2018, John Hubbard wrote:
> > If you establish a reference to a page then increase the page count. If
> > the reference is a dma pin action also then increase the pinned count.
> >
> > That way you know how many of the references to the page are dma
> > pins and you can correctly man
On 07/02/2018 05:08 PM, Christopher Lameter wrote:
> On Mon, 2 Jul 2018, John Hubbard wrote:
>
>>>
>>> These two are just wrong. You cannot make any page reference for
>>> PageDmaPinned() account against a pin count. First, it is just conceptually
>>> wrong as these references need not be long ter
On Mon, 2 Jul 2018, John Hubbard wrote:
> >
> > These two are just wrong. You cannot make any page reference for
> > PageDmaPinned() account against a pin count. First, it is just conceptually
> > wrong as these references need not be long term pins, second, you can
> > easily race like:
> >
> > P
On 07/02/2018 02:53 AM, Jan Kara wrote:
> On Sun 01-07-18 17:56:53, john.hubb...@gmail.com wrote:
>> From: John Hubbard
>>
> ...
>
>> @@ -904,12 +907,24 @@ static inline void get_page(struct page *page)
>> */
>> VM_BUG_ON_PAGE(page_ref_count(page) <= 0, page);
>> page_ref_inc(page
On Sun 01-07-18 17:56:53, john.hubb...@gmail.com wrote:
> From: John Hubbard
>
> This patch sets and restores the new page->dma_pinned_flags and
> page->dma_pinned_count fields, but does not actually use them for
> anything yet.
>
> In order to use these fields at all, the page must be removed f
On 07/01/2018 07:58 PM, kbuild test robot wrote:
> Hi John,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on linus/master]
> [also build test WARNING on v4.18-rc3]
> [cannot apply to next-20180629]
> [if your patch is applied to the wrong git tree, please
Hi John,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on linus/master]
[also build test WARNING on v4.18-rc3]
[cannot apply to next-20180629]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system]
url:
https://gi
Hi John,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.18-rc3]
[cannot apply to next-20180629]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system]
url:
https://github.com
From: John Hubbard
This patch sets and restores the new page->dma_pinned_flags and
page->dma_pinned_count fields, but does not actually use them for
anything yet.
In order to use these fields at all, the page must be removed from
any LRU list that it's on. The patch also adds some precautions th
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