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Fri, 19 Jun 2020 14:56:59 -0700 From: Ralph Campbell To: , , , , CC: Jerome Glisse , John Hubbard , Christoph Hellwig , Jason Gunthorpe , "Ben Skeggs" , Andrew Morton , Shuah Khan , Ralph Campbell Subject: [PATCH 12/16] mm/hmm: optimize migrate_vma_setup() for holes Date: Fri, 19 Jun 2020 14:56:45 -0700 Message-ID: <20200619215649.32297-13-rcampbell@nvidia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200619215649.32297-1-rcampbell@nvidia.com> References: <20200619215649.32297-1-rcampbell@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public Content-Transfer-Encoding: quoted-printable Content-Type: text/plain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1592603814; bh=axo1qROEDM7hJwmmu8OcpvGAO/8DiPu78Ea49fo3JP8=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=NIxcE9Fdl7sawaTciO5YlsjyXWpVEzFy0PbON2Sjk/IyFNSrBJ3Z0/rsrrAxkjrPQ Gf9NZudc7Nbt8Zl7jnG+RRXt4NWhRcV1pDwSpZrAuJLTXo3sCmo+0KRW4p1KpP1C2O IGlJdkSh1pbgcUuFPE/eHS9ARNZCW+Vct1T3yR8P47uoaS0F8MUoGYnVrVSCAeuAAL Wa0mn3fQfKu6brwDG1bL1YBu9wmXB2HDxw8Ozxh5DG7e9SaU/k/qtMIomYAX5KoRsN dROV2rrac8AawgKXAEL67b2guP7Gye49n/ClaiscMGrEh5ewh1ZOYWwMOdfQ2WKXZS jeiLsbDR/xcHw== X-Rspamd-Queue-Id: 544B0100EDBFF X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When migrating system memory to device private memory, if the source address range is a valid VMA range and there is no memory or a zero page, the source PFN array is marked as valid but with no PFN. This lets the device driver allocate private memory and clear it, then insert the new device private struct page into the CPU's page tables when migrate_vma_pages() is called. migrate_vma_pages() only inserts the new page if the VMA is an anonymous range. There is no point in telling the device driver to allocate device private memory and then throwing it away. Instead, mark the source PFN array entries as not migrating to avoid this overhead. Signed-off-by: Ralph Campbell --- mm/migrate.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 24535281cea3..87c52e0ee580 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2178,9 +2178,13 @@ static int migrate_vma_collect_hole(unsigned long st= art, { struct migrate_vma *migrate =3D walk->private; unsigned long addr; + unsigned long flags; + + /* Only allow populating anonymous memory */ + flags =3D vma_is_anonymous(walk->vma) ? MIGRATE_PFN_MIGRATE : 0; =20 for (addr =3D start; addr < end; addr +=3D PAGE_SIZE) { - migrate->src[migrate->npages] =3D MIGRATE_PFN_MIGRATE; + migrate->src[migrate->npages] =3D flags; migrate->dst[migrate->npages] =3D 0; migrate->npages++; migrate->cpages++; @@ -2748,7 +2752,7 @@ static void migrate_vma_insert_page(struct migrate_vm= a *migrate, pte_t *ptep; =20 /* Only allow populating anonymous memory */ - if (!vma_is_anonymous(vma)) + if (WARN_ON_ONCE(!vma_is_anonymous(vma))) goto abort; =20 pgdp =3D pgd_offset(mm, addr); --=20 2.20.1