[PATCH v12 36/69] xtensa: remove vma linked list walks

Liam Howlett
2022-07-20T02:22:09Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

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.

Link: https://lkml.kernel.org/r/20220504011345.662299-21-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20220621204632.3370049-37-Liam.Howlett@oracle.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
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
--
2.35.1