Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Daniel Jordan <> | Subject | [PATCH 3/6] vfio/spapr_tce: drop mmap_sem now that locked_vm is atomic | Date | Tue, 2 Apr 2019 16:41:55 -0400 |
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With locked_vm now an atomic, there is no need to take mmap_sem as writer. Delete and refactor accordingly.
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Alexey Kardashevskiy <aik@ozlabs.ru> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <linux-mm@kvack.org> Cc: <kvm@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> --- drivers/vfio/vfio_iommu_spapr_tce.c | 36 ++++++++++++----------------- 1 file changed, 15 insertions(+), 21 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c index e7d787e5d839..7675a3b28410 100644 --- a/drivers/vfio/vfio_iommu_spapr_tce.c +++ b/drivers/vfio/vfio_iommu_spapr_tce.c @@ -36,8 +36,9 @@ static void tce_iommu_detach_group(void *iommu_data, 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(struct mm_struct *mm, long npages) 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); - - 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" : ""); + atomic64_sub(npages, &mm->locked_vm); + } - 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); } /* -- 2.21.0
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