The patch titled
Subject: vfio/type1: drop mmap_sem now that locked_vm is atomic
has been added to the -mm tree. Its filename is
vfio-type1-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/vfio-type1-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/vfio-type1-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
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From: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Subject: vfio/type1: drop mmap_sem now that locked_vm is atomic
With locked_vm now an atomic, there is no need to take mmap_sem as writer.
Delete and refactor accordingly.
Link: http://lkml.kernel.org/r/20190402204158.27582-3-daniel.m.jordan@xxxxxxxxxx
Signed-off-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Alan Tull <atull@xxxxxxxxxx>
Cc: Alexey Kardashevskiy <aik@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Moritz Fischer <mdf@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Wu Hao <hao.wu@xxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/vfio/vfio_iommu_type1.c | 27 +++++++++------------------
1 file changed, 9 insertions(+), 18 deletions(-)
--- a/drivers/vfio/vfio_iommu_type1.c~vfio-type1-drop-mmap_sem-now-that-locked_vm-is-atomic
+++ a/drivers/vfio/vfio_iommu_type1.c
@@ -263,7 +263,8 @@ static int vfio_iova_put_vfio_pfn(struct
static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async)
{
struct mm_struct *mm;
- int ret;
+ s64 locked_vm;
+ int ret = 0;
if (!npage)
return 0;
@@ -272,25 +273,15 @@ static int vfio_lock_acct(struct vfio_dm
if (!mm)
return -ESRCH; /* process exited */
- ret = down_write_killable(&mm->mmap_sem);
- if (!ret) {
- if (npage > 0) {
- if (!dma->lock_cap) {
- s64 locked_vm = atomic64_read(&mm->locked_vm);
- unsigned long limit;
+ locked_vm = atomic64_add_return(npage, &mm->locked_vm);
- limit = task_rlimit(dma->task,
- RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-
- if (locked_vm + npage > limit)
- ret = -ENOMEM;
- }
+ if (npage > 0 && !dma->lock_cap) {
+ unsigned long limit = task_rlimit(dma->task, RLIMIT_MEMLOCK) >>
+ PAGE_SHIFT;
+ if (locked_vm > limit) {
+ atomic64_sub(npage, &mm->locked_vm);
+ ret = -ENOMEM;
}
-
- if (!ret)
- atomic64_add(npage, &mm->locked_vm);
-
- up_write(&mm->mmap_sem);
}
if (async)
_
Patches currently in -mm which might be from daniel.m.jordan@xxxxxxxxxx are
mm-change-locked_vms-type-from-unsigned-long-to-atomic64_t.patch
vfio-type1-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
vfio-spapr_tce-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
fpga-dlf-afu-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
powerpc-mmu-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
kvm-book3s-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
