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Re: [PATCH 17/19] dm: get rid of superfluous gfp flags

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On Fri, 15 Apr 2016, Michal Hocko wrote:

> On Fri 15-04-16 08:29:28, Mikulas Patocka wrote:
> > 
> > 
> > On Mon, 11 Apr 2016, Michal Hocko wrote:
> > 
> > > From: Michal Hocko <mhocko@suse.com>
> > > 
> > > copy_params seems to be little bit confused about which allocation flags
> > > to use. It enforces GFP_NOIO even though it uses
> > > memalloc_noio_{save,restore} which enforces GFP_NOIO at the page
> > 
> > memalloc_noio_{save,restore} is used because __vmalloc is flawed and 
> > doesn't respect GFP_NOIO properly (it doesn't use gfp flags when 
> > allocating pagetables).
> 
> Yes and there are no plans to change __vmalloc to properly propagate gfp
> flags through the whole call chain and that is why we have
> memalloc_noio thingy. If that ever changes later the GFP_NOIO can be
> added in favor of memalloc_noio API. Both are clearly redundant.
> -- 
> Michal Hocko
> SUSE Labs

You could move memalloc_noio_{save,restore} to __vmalloc. Something like

if (!(gfp_mask & __GFP_IO))
	noio_flag = memalloc_noio_save();
...
if (!(gfp_mask & __GFP_IO))
	memalloc_noio_restore(noio_flag);

That would be better than repeating this hack in every __vmalloc caller 
that need GFP_NOIO.

Mikulas

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[PATCH 0/19] get rid of superfluous __GFP_REPORT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:10 +0200
  [PATCH 15/19] tile: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:10 +0200
  [PATCH 18/19] crypto: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:10 +0200
    Re: [PATCH 18/19] crypto: get rid of superfluous __GFP_REPEAT Herbert Xu <herbert@gondor.apana.org.au> - 2016-04-14 08:30 +0200
      Re: [PATCH 18/19] crypto: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-14 09:10 +0200
        Re: [PATCH 18/19] crypto: get rid of superfluous __GFP_REPEAT Herbert Xu <herbert@gondor.apana.org.au> - 2016-04-14 10:20 +0200
    [PATCH resend] crypto: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-14 11:00 +0200
      Re: [PATCH resend] crypto: get rid of superfluous __GFP_REPEAT Herbert Xu <herbert@gondor.apana.org.au> - 2016-04-15 16:40 +0200
  [PATCH 09/19] parisc: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:10 +0200
  [PATCH 16/19] unicore32: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:10 +0200
  [PATCH 08/19] nios2: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
  [PATCH 01/19] tree wide: get rid of __GFP_REPEAT for order-0 allocations part I Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
    Re: [PATCH 01/19] tree wide: get rid of __GFP_REPEAT for order-0  allocations part I David Rientjes <rientjes@google.com> - 2016-04-14 22:00 +0200
      Re: [PATCH 01/19] tree wide: get rid of __GFP_REPEAT for order-0  allocations part I Michal Hocko <mhocko@kernel.org> - 2016-04-15 09:50 +0200
  [PATCH 06/19] arc: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
    Re: [PATCH 06/19] arc: get rid of superfluous __GFP_REPEAT Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-04-11 16:30 +0200
  [PATCH 11/19] powerpc: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
  [PATCH 10/19] score: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
  [PATCH 07/19] mips: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
  [PATCH 19/19] jbd2: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
  [PATCH 13/19] s390: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
    Re: [PATCH 13/19] s390: get rid of superfluous __GFP_REPEAT Cornelia Huck <cornelia.huck@de.ibm.com> - 2016-04-11 13:30 +0200
      Re: [PATCH 13/19] s390: get rid of superfluous __GFP_REPEAT Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-04-11 14:50 +0200
  [PATCH 12/19] sparc: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
  [PATCH 04/19] arm: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
  [PATCH 03/19] x86/efi: get rid of superfluous __GFP_REPEAT Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
    Re: [PATCH 03/19] x86/efi: get rid of superfluous __GFP_REPEAT Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-12 18:00 +0200
  [PATCH 17/19] dm: get rid of superfluous gfp flags Michal Hocko <mhocko@kernel.org> - 2016-04-11 13:20 +0200
    Re: [PATCH 17/19] dm: get rid of superfluous gfp flags Mikulas Patocka <mpatocka@redhat.com> - 2016-04-15 14:30 +0200
      Re: [PATCH 17/19] dm: get rid of superfluous gfp flags Michal Hocko <mhocko@kernel.org> - 2016-04-15 15:10 +0200
        Re: [PATCH 17/19] dm: get rid of superfluous gfp flags Mikulas Patocka <mpatocka@redhat.com> - 2016-04-15 20:50 +0200
          Re: [PATCH 17/19] dm: get rid of superfluous gfp flags Michal Hocko <mhocko@kernel.org> - 2016-04-16 22:40 +0200
            Re: [PATCH 17/19] dm: get rid of superfluous gfp flags Michal Hocko <mhocko@kernel.org> - 2016-04-22 14:50 +0200
              Re: [PATCH 17/19] dm: get rid of superfluous gfp flags Mikulas Patocka <mpatocka@redhat.com> - 2016-04-26 19:30 +0200
                Re: [PATCH 17/19] dm: get rid of superfluous gfp flags Michal Hocko <mhocko@kernel.org> - 2016-04-27 10:40 +0200
  CC in git cover letter vs patches (was Re: [PATCH 0/19] get rid of  superfluous __GFP_REPORT) Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2016-04-13 13:30 +0200
    Re: CC in git cover letter vs patches (was Re: [PATCH 0/19] get rid  of superfluous __GFP_REPORT) Michal Hocko <mhocko@kernel.org> - 2016-04-13 15:40 +0200

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