linux-kernel - [PATCH v6 37/71] xtensa: Remove vma linked list walks

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Date:   Tue, 15 Feb 2022 14:43:16 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v6 37/71] xtensa: Remove vma linked list walks

From: "Liam R. Howlett" <Liam.Howlett@...cle.com>

Use the VMA iterator instead.  Since VMA can no longer be NULL in the
loop, then deal with out-of-memory outside the loop.  This means a
slightly longer run time in the failure case (-ENOMEM) - it will run to
the end of the VMAs before erroring instead of in the middle of the
loop.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 arch/xtensa/kernel/syscall.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c
index 201356faa7e6..b3c2450d6f23 100644
--- a/arch/xtensa/kernel/syscall.c
+++ b/arch/xtensa/kernel/syscall.c
@@ -58,6 +58,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags)
 {
 	struct vm_area_struct *vmm;
+	struct vma_iterator vmi;
 
 	if (flags & MAP_FIXED) {
 		/* We do not accept a shared mapping if it would violate
@@ -79,15 +80,20 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	else
 		addr = PAGE_ALIGN(addr);
 
-	for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
-		/* At this point:  (!vmm || addr < vmm->vm_end). */
-		if (TASK_SIZE - len < addr)
-			return -ENOMEM;
-		if (!vmm || addr + len <= vm_start_gap(vmm))
-			return addr;
+	vma_iter_init(&vmi, current->mm, addr);
+	for_each_vma(vmi, vmm) {
+		/* At this point:  (addr < vmm->vm_end). */
+		if (addr + len <= vm_start_gap(vmm))
+			break;
+
 		addr = vmm->vm_end;
 		if (flags & MAP_SHARED)
 			addr = COLOUR_ALIGN(addr, pgoff);
 	}
+
+	if (TASK_SIZE - len < addr)
+		return -ENOMEM;
+
+	return addr;
 }
 #endif
-- 
2.34.1