Re: [PATCH] mm: change may_enter_fs check condition

From: yalin wang
Date: Sun Nov 15 2015 - 20:38:39 EST



> On Nov 13, 2015, at 23:36, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
>
> On Fri 13-11-15 13:01:16, Vlastimil Babka wrote:
>> On 11/13/2015 12:47 PM, yalin wang wrote:
>>> Add page_is_file_cache() for __GFP_FS check,
>>> otherwise, a Pageswapcache() && PageDirty() page can always be write
>>> back if the gfp flag is __GFP_FS, this is not the expected behavior.
>>
>> I'm not sure I understand your point correctly *), but you seem to imply
>> that there would be an allocation that has __GFP_FS but doesn't have
>> __GFP_IO? Are there such allocations and does it make sense?
>
> No it doesn't. There is a natural layering here and __GFP_FS allocations
> should contain __GFP_IO.
>
> The patch as is makes only little sense to me. Are you seeing any issue
> which this is trying to fix?
mm..
i donât see issue for this part ,
just feel confuse when i see code about this part ,
then i make a patch for this .
i am not sure if __GFP_FS will make sure __GFP_IO flag must be always set.
if it is , i think can add comment here to make people clear . :)

Thanks

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