Re: Question on ___GFP_NOLOCKDEP - Was: Re: [PATCH 1/1] Remove hardcoding of ___GFP_xxx bitmasks

[Michal Hocko]

On Thu 27-04-17 15:16:47, Igor Stoppa wrote:
> On 26/04/17 18:29, Igor Stoppa wrote:
> 
> > On 26/04/17 17:47, Michal Hocko wrote:
> 
> [...]
> 
> >> Also the current mm tree has ___GFP_NOLOCKDEP which is not addressed
> >> here so I suspect you have based your change on the Linus tree.
> 
> > I used your tree from kernel.org
> 
> I found it, I was using master, instead of auto-latest (is it correct?)

yes

> But now I see something that I do not understand (apologies if I'm
> asking something obvious).
> 
> First there is:
> 
> [...]
> #define ___GFP_WRITE		0x800000u
> #define ___GFP_KSWAPD_RECLAIM	0x1000000u
> #ifdef CONFIG_LOCKDEP
> #define ___GFP_NOLOCKDEP	0x4000000u
> #else
> #define ___GFP_NOLOCKDEP	0
> #endif
> 
> Then:
> 
> /* Room for N __GFP_FOO bits */
> #define __GFP_BITS_SHIFT (25 + IS_ENABLED(CONFIG_LOCKDEP))
> 
> 
> 
> Shouldn't it be either:
> ___GFP_NOLOCKDEP	0x2000000u

Yes it should. At the time when this patch was written this value was
used. Later I've removed __GFP_OTHER by 41b6167e8f74 ("mm: get rid of
__GFP_OTHER_NODE") and forgot to refresh this one. Thanks for noticing
this.

Andrew, could you fold the following in please?
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