linux-kernel - Re: [PATCH V7 1/4] mm/cma: Add PF flag to force non cma alloc

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Date:   Tue, 29 Jan 2019 14:52:53 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
Cc:     Michal Hocko <mhocko@...nel.org>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        David Gibson <david@...son.dropbear.id.au>,
        Andrea Arcangeli <aarcange@...hat.com>, mpe@...erman.id.au,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH V7 1/4] mm/cma: Add PF flag to force non cma alloc

On Mon, 14 Jan 2019 15:24:33 +0530 "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com> wrote:

> This patch adds PF_MEMALLOC_NOCMA which make sure any allocation in that context
> is marked non-movable and hence cannot be satisfied by CMA region.
> 
> This is useful with get_user_pages_longterm where we want to take a page pin by
> migrating pages from CMA region. Marking the section PF_MEMALLOC_NOCMA ensures
> that we avoid unnecessary page migration later.
> 
> ...
>
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1406,6 +1406,7 @@ extern struct pid *cad_pid;
>  #define PF_RANDOMIZE		0x00400000	/* Randomize virtual address space */
>  #define PF_SWAPWRITE		0x00800000	/* Allowed to write to swap */
>  #define PF_MEMSTALL		0x01000000	/* Stalled due to lack of memory */
> +#define PF_MEMALLOC_NOCMA	0x02000000	/* All allocation request will have _GFP_MOVABLE cleared */
>  #define PF_NO_SETAFFINITY	0x04000000	/* Userland is not allowed to meddle with cpus_allowed */
>  #define PF_MCE_EARLY		0x08000000      /* Early kill for mce process policy */
>  #define PF_MUTEX_TESTER		0x20000000	/* Thread belongs to the rt mutex tester */

This flag has been taken by PF_UMH so I moved it to 0x10000000.

And we have now run out of PF_ flags.