linux-kernel - [PATCH v1 09/12] powerpc/pseries: CMM: Switch to balloon_page

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Message-Id: <20191031142933.10779-10-david@redhat.com>
Date:   Thu, 31 Oct 2019 15:29:30 +0100
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Arun KS <arunks@...eaurora.org>
Subject: [PATCH v1 09/12] powerpc/pseries: CMM: Switch to balloon_page_alloc()

balloon_page_alloc() will use GFP_HIGHUSER_MOVABLE in case we have
CONFIG_BALLOON_COMPACTION. This is now possible, as balloon pages are
movable with CONFIG_BALLOON_COMPACTION. Without
CONFIG_BALLOON_COMPACTION, GFP_HIGHUSER is used.

Note that apart from that, balloon_page_alloc() uses the following
flags:
    __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN
And current code used:
    GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC

GFP_HIGHUSER/GFP_HIGHUSER_MOVABLE include
    __GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL | __GFP_HIGHMEM

GFP_NOIO is __GFP_RECLAIM.

With CONFIG_BALLOON_COMPACTION, we essentially add:
    __GFP_IO | __GFP_FS | __GFP_HARDWALL | __GFP_HIGHMEM | __GFP_MOVABLE

Without CONFIG_BALLOON_COMPACTION, we essentially add:
    __GFP_IO | __GFP_FS | __GFP_HARDWALL | __GFP_HIGHMEM

I assume this is fine, as this is what all other balloon compaction
users use. If it turns out to be a problem, we could add
__GFP_MOVABLE manually if we have CONFIG_BALLOON_COMPACTION.

Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Pavel Tatashin <pasha.tatashin@...een.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Arun KS <arunks@...eaurora.org>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 arch/powerpc/platforms/pseries/cmm.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
index 235fd7fe9df1..a6ec2bbb1f91 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -147,8 +147,7 @@ static long cmm_alloc_pages(long nr)
 			break;
 		}
 
-		page = alloc_page(GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY |
-				  __GFP_NOMEMALLOC);
+		page = balloon_page_alloc();
 		if (!page)
 			break;
 		rc = plpar_page_set_loaned(page);
-- 
2.21.0