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From:   Liam Howlett <liam.howlett@oracle.com>
To:     "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>
CC:     Yu Zhao <yuzhao@google.com>
Subject: [PATCH v12 37/69] cxl: remove vma linked list walk
Thread-Topic: [PATCH v12 37/69] cxl: remove vma linked list walk
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Date:   Wed, 20 Jul 2022 02:17:56 +0000
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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Use the VMA iterator instead.  This requires a little restructuring of the
surrounding code to hoist the mm to the caller.  That turns
cxl_prefault_one() into a trivial function, so call cxl_fault_segment()
directly.

Link: https://lkml.kernel.org/r/20220504011345.662299-22-Liam.Howlett@oracl=
e.com
Link: https://lkml.kernel.org/r/20220621204632.3370049-38-Liam.Howlett@orac=
le.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 drivers/misc/cxl/fault.c | 45 ++++++++++++++--------------------------
 1 file changed, 15 insertions(+), 30 deletions(-)

diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c
index 60c829113299..2c64f55cf01f 100644
--- a/drivers/misc/cxl/fault.c
+++ b/drivers/misc/cxl/fault.c
@@ -280,22 +280,6 @@ void cxl_handle_fault(struct work_struct *fault_work)
 		mmput(mm);
 }
=20
-static void cxl_prefault_one(struct cxl_context *ctx, u64 ea)
-{
-	struct mm_struct *mm;
-
-	mm =3D get_mem_context(ctx);
-	if (mm =3D=3D NULL) {
-		pr_devel("cxl_prefault_one unable to get mm %i\n",
-			 pid_nr(ctx->pid));
-		return;
-	}
-
-	cxl_fault_segment(ctx, mm, ea);
-
-	mmput(mm);
-}
-
 static u64 next_segment(u64 ea, u64 vsid)
 {
 	if (vsid & SLB_VSID_B_1T)
@@ -306,23 +290,16 @@ static u64 next_segment(u64 ea, u64 vsid)
 	return ea + 1;
 }
=20
-static void cxl_prefault_vma(struct cxl_context *ctx)
+static void cxl_prefault_vma(struct cxl_context *ctx, struct mm_struct *mm=
)
 {
 	u64 ea, last_esid =3D 0;
 	struct copro_slb slb;
+	VMA_ITERATOR(vmi, mm, 0);
 	struct vm_area_struct *vma;
 	int rc;
-	struct mm_struct *mm;
-
-	mm =3D get_mem_context(ctx);
-	if (mm =3D=3D NULL) {
-		pr_devel("cxl_prefault_vm unable to get mm %i\n",
-			 pid_nr(ctx->pid));
-		return;
-	}
=20
 	mmap_read_lock(mm);
-	for (vma =3D mm->mmap; vma; vma =3D vma->vm_next) {
+	for_each_vma(vmi, vma) {
 		for (ea =3D vma->vm_start; ea < vma->vm_end;
 				ea =3D next_segment(ea, slb.vsid)) {
 			rc =3D copro_calculate_slb(mm, ea, &slb);
@@ -337,20 +314,28 @@ static void cxl_prefault_vma(struct cxl_context *ctx)
 		}
 	}
 	mmap_read_unlock(mm);
-
-	mmput(mm);
 }
=20
 void cxl_prefault(struct cxl_context *ctx, u64 wed)
 {
+	struct mm_struct *mm =3D get_mem_context(ctx);
+
+	if (mm =3D=3D NULL) {
+		pr_devel("cxl_prefault unable to get mm %i\n",
+			 pid_nr(ctx->pid));
+		return;
+	}
+
 	switch (ctx->afu->prefault_mode) {
 	case CXL_PREFAULT_WED:
-		cxl_prefault_one(ctx, wed);
+		cxl_fault_segment(ctx, mm, wed);
 		break;
 	case CXL_PREFAULT_ALL:
-		cxl_prefault_vma(ctx);
+		cxl_prefault_vma(ctx, mm);
 		break;
 	default:
 		break;
 	}
+
+	mmput(mm);
 }
--=20
2.35.1