The patch titled
Subject: vfio/spapr_tce: drop mmap_sem now that locked_vm is atomic
has been added to the -mm tree. Its filename is
vfio-spapr_tce-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/vfio-spapr_tce-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/vfio-spapr_tce-drop-mmap_sem-now-that-locked_vm-is-atomic.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Subject: vfio/spapr_tce: 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/20190402204158.27582-4-daniel.m.jordan@xxxxxxxxxx
Signed-off-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Cc: Alexey Kardashevskiy <aik@xxxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Alan Tull <atull@xxxxxxxxxx>
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_spapr_tce.c | 36 ++++++++++----------------
1 file changed, 15 insertions(+), 21 deletions(-)
--- a/drivers/vfio/vfio_iommu_spapr_tce.c~vfio-spapr_tce-drop-mmap_sem-now-that-locked_vm-is-atomic
+++ a/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -36,8 +36,9 @@ static void tce_iommu_detach_group(void
static long try_increment_locked_vm(struct mm_struct *mm, long npages)
{
- long ret = 0, lock_limit;
+ long ret = 0;
s64 locked;
+ unsigned long lock_limit;
if (WARN_ON_ONCE(!mm))
return -EPERM;
@@ -45,39 +46,32 @@ static long try_increment_locked_vm(stru
if (!npages)
return 0;
- down_write(&mm->mmap_sem);
- locked = atomic64_read(&mm->locked_vm) + npages;
+ locked = atomic64_add_return(npages, &mm->locked_vm);
lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
- if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+ if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
ret = -ENOMEM;
- else
- atomic64_add(npages, &mm->locked_vm);
+ atomic64_sub(npages, &mm->locked_vm);
+ }
- pr_debug("[%d] RLIMIT_MEMLOCK +%ld %ld/%ld%s\n", current->pid,
- npages << PAGE_SHIFT,
- atomic64_read(&mm->locked_vm) << PAGE_SHIFT,
- rlimit(RLIMIT_MEMLOCK),
- ret ? " - exceeded" : "");
-
- up_write(&mm->mmap_sem);
+ pr_debug("[%d] RLIMIT_MEMLOCK +%ld %lld/%lu%s\n", current->pid,
+ npages << PAGE_SHIFT, locked << PAGE_SHIFT,
+ lock_limit, ret ? " - exceeded" : "");
return ret;
}
static void decrement_locked_vm(struct mm_struct *mm, long npages)
{
+ s64 locked;
+
if (!mm || !npages)
return;
- down_write(&mm->mmap_sem);
- if (WARN_ON_ONCE(npages > atomic64_read(&mm->locked_vm)))
- npages = atomic64_read(&mm->locked_vm);
- atomic64_sub(npages, &mm->locked_vm);
- pr_debug("[%d] RLIMIT_MEMLOCK -%ld %ld/%ld\n", current->pid,
- npages << PAGE_SHIFT,
- atomic64_read(&mm->locked_vm) << PAGE_SHIFT,
+ locked = atomic64_sub_return(npages, &mm->locked_vm);
+ WARN_ON_ONCE(locked < 0);
+ pr_debug("[%d] RLIMIT_MEMLOCK -%ld %lld/%lu\n", current->pid,
+ npages << PAGE_SHIFT, locked << PAGE_SHIFT,
rlimit(RLIMIT_MEMLOCK));
- up_write(&mm->mmap_sem);
}
/*
_
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
