From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
akpm@linux-foundation.org, Alexey Kardashevskiy <aik@ozlabs.ru>,
David Gibson <david@gibson.dropbear.id.au>,
Andrea Arcangeli <aarcange@redhat.com>,
mpe@ellerman.id.au, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v8 1/4] mm/cma: Add PF flag to force non cma alloc
Date: Thu, 28 Feb 2019 15:34:05 +0100 [thread overview]
Message-ID: <20190228143405.GF10588@dhcp22.suse.cz> (raw)
In-Reply-To: <1d083bf9-0beb-0c49-9aab-c6bc14da46ea@suse.cz>
On Thu 28-02-19 13:20:03, Vlastimil Babka wrote:
> On 2/27/19 3:47 PM, Aneesh Kumar K.V 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.
> >
> > Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
> > Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
> > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>
> +CC scheduler guys
>
> Do we really take the last available PF flag just so that "we avoid
> unnecessary page migration later"?
> If yes, that's a third PF_MEMALLOC flag, should we get separate variable
> for gfp context at this point?
Yes, that sounds like a reasonable thing to do. Just note that xfs still
uses current_{set,restore}* api to handle PF_MEMALLOC_NOFS so that would
have to be moved over to the memalloc_nofs_{save,restore} API.
--
Michal Hocko
next prev parent reply other threads:[~2019-02-28 14:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-27 14:47 [PATCH v8 0/4] mm/kvm/vfio/ppc64: Migrate compound pages out of CMA region Aneesh Kumar K.V
2019-02-27 14:47 ` [PATCH v8 1/4] mm/cma: Add PF flag to force non cma alloc Aneesh Kumar K.V
2019-02-28 12:20 ` Vlastimil Babka
2019-02-28 14:34 ` Michal Hocko [this message]
2019-02-27 14:47 ` [PATCH v8 2/4] mm: Update get_user_pages_longterm to migrate pages allocated from CMA region Aneesh Kumar K.V
2019-02-27 14:47 ` [PATCH v8 3/4] powerpc/mm/iommu: Allow migration of cma allocated pages during mm_iommu_do_alloc Aneesh Kumar K.V
2019-02-27 14:47 ` [PATCH v8 4/4] powerpc/mm/iommu: Allow large IOMMU page size only for hugetlb backing Aneesh Kumar K.V
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