linux-kernel - [PATCH 2/9] mm/migrate.c: Allow pfn flags to be passed to migrate_vma

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Message-ID: <20210209010722.13839-3-apopple@nvidia.com>
Date:   Tue, 9 Feb 2021 12:07:15 +1100
From:   Alistair Popple <apopple@...dia.com>
To:     <linux-mm@...ck.org>, <nouveau@...ts.freedesktop.org>,
        <bskeggs@...hat.com>, <akpm@...ux-foundation.org>
CC:     <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <kvm-ppc@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <jhubbard@...dia.com>, <rcampbell@...dia.com>,
        <jglisse@...hat.com>, "Alistair Popple" <apopple@...dia.com>
Subject: [PATCH 2/9] mm/migrate.c: Allow pfn flags to be passed to migrate_vma_setup()

Currently migrate_vma_setup() zeros both src and dst pfn arrays. This
means it is not possible to pass per-pfn flags to migrate_vma_setup(). A
future patch introduces per-pfn flags for migrate_vma_setup(), so ensure
existing callers will not be affected by having the caller zero both src
and dst pfn arrays.

Signed-off-by: Alistair Popple <apopple@...dia.com>
---
 arch/powerpc/kvm/book3s_hv_uvmem.c | 4 ++--
 lib/test_hmm.c                     | 6 ++++--
 mm/migrate.c                       | 1 -
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 84e5a2dc8be5..d434783b272a 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -506,7 +506,7 @@ static int __kvmppc_svm_page_out(struct vm_area_struct *vma,
 		unsigned long end, unsigned long page_shift,
 		struct kvm *kvm, unsigned long gpa)
 {
-	unsigned long src_pfn, dst_pfn = 0;
+	unsigned long src_pfn = 0, dst_pfn = 0;
 	struct migrate_vma mig;
 	struct page *dpage, *spage;
 	struct kvmppc_uvmem_page_pvt *pvt;
@@ -732,7 +732,7 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma,
 		unsigned long page_shift,
 		bool pagein)
 {
-	unsigned long src_pfn, dst_pfn = 0;
+	unsigned long src_pfn = 0, dst_pfn = 0;
 	struct migrate_vma mig;
 	struct page *spage;
 	unsigned long pfn;
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 80a78877bd93..98848b96ff09 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -696,6 +696,8 @@ static int dmirror_migrate(struct dmirror *dmirror,
 		if (next > vma->vm_end)
 			next = vma->vm_end;
 
+		memset(src_pfns, 0, ARRAY_SIZE(src_pfns));
+		memset(dst_pfns, 0, ARRAY_SIZE(dst_pfns));
 		args.vma = vma;
 		args.src = src_pfns;
 		args.dst = dst_pfns;
@@ -1025,8 +1027,8 @@ static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
 static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
 {
 	struct migrate_vma args;
-	unsigned long src_pfns;
-	unsigned long dst_pfns;
+	unsigned long src_pfns = 0;
+	unsigned long dst_pfns = 0;
 	struct page *rpage;
 	struct dmirror *dmirror;
 	vm_fault_t ret;
diff --git a/mm/migrate.c b/mm/migrate.c
index 053228559fd3..fe8bb322e2e3 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2874,7 +2874,6 @@ int migrate_vma_setup(struct migrate_vma *args)
 	if (!args->src || !args->dst)
 		return -EINVAL;
 
-	memset(args->src, 0, sizeof(*args->src) * nr_pages);
 	args->cpages = 0;
 	args->npages = 0;
 
-- 
2.20.1