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

From Mikulas Patocka <mpatocka@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH 17/19] dm: get rid of superfluous gfp flags
Date 2016-04-15 14:30 +0200
Message-ID <rob2N-2XS-5@gated-at.bofh.it> (permalink)
References <rmHTb-4Qu-3@gated-at.bofh.it> <rmI2T-4Vk-37@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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).

The proper fix it to correct __vmalloc (though, it would require change to 
pagetable allocation routine on all architectures), not to remove GFP_NOIO 
from __vmalloc.

Mikulas

> allocator level automatically (via memalloc_noio_flags). It also
> uses __GFP_REPEAT for the __vmalloc request which doesn't make much
> sense either because vmalloc doesn't rely on costly high order
> allocations.
> 
> Cc: Shaohua Li <shli@kernel.org>
> Cc: Mikulas Patocka <mpatocka@redhat.com>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  drivers/md/dm-ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
> index 2adf81d81fca..dfe629a294e1 100644
> --- a/drivers/md/dm-ioctl.c
> +++ b/drivers/md/dm-ioctl.c
> @@ -1723,7 +1723,7 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
>  	if (!dmi) {
>  		unsigned noio_flag;
>  		noio_flag = memalloc_noio_save();
> -		dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
> +		dmi = __vmalloc(param_kernel->data_size, __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
>  		memalloc_noio_restore(noio_flag);
>  		if (dmi)
>  			*param_flags |= DM_PARAMS_VMALLOC;
> -- 
> 2.8.0.rc3
> 

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Thread

[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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