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Subject[PATCH 4/5] powerpc/mmu: use pinned_vm instead of locked_vm to account pinned pages
Date
Beginning with bc3e53f682d9 ("mm: distinguish between mlocked and pinned
pages"), locked and pinned pages are accounted separately. The IOMMU
MMU helpers on powerpc account pinned pages to locked_vm; use pinned_vm
instead.

pinned_vm recently became atomic and so no longer relies on mmap_sem
held as writer: delete.

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
---
arch/powerpc/mm/mmu_context_iommu.c | 43 ++++++++++++++---------------
1 file changed, 21 insertions(+), 22 deletions(-)

diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
index a712a650a8b6..fdf670542847 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -40,36 +40,35 @@ struct mm_iommu_table_group_mem_t {
u64 dev_hpa; /* Device memory base address */
};

-static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
+static long mm_iommu_adjust_pinned_vm(struct mm_struct *mm,
unsigned long npages, bool incr)
{
- long ret = 0, locked, lock_limit;
+ long ret = 0;
+ unsigned long lock_limit;
+ s64 pinned_vm;

if (!npages)
return 0;

- down_write(&mm->mmap_sem);
-
if (incr) {
- locked = mm->locked_vm + npages;
lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
- if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+ pinned_vm = atomic64_add_return(npages, &mm->pinned_vm);
+ if (pinned_vm > lock_limit && !capable(CAP_IPC_LOCK)) {
ret = -ENOMEM;
- else
- mm->locked_vm += npages;
+ atomic64_sub(npages, &mm->pinned_vm);
+ }
} else {
- if (WARN_ON_ONCE(npages > mm->locked_vm))
- npages = mm->locked_vm;
- mm->locked_vm -= npages;
+ pinned_vm = atomic64_read(&mm->pinned_vm);
+ if (WARN_ON_ONCE(npages > pinned_vm))
+ npages = pinned_vm;
+ atomic64_sub(npages, &mm->pinned_vm);
}

- pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%ld %ld/%ld\n",
- current ? current->pid : 0,
- incr ? '+' : '-',
+ pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%lu %ld/%lu\n",
+ current ? current->pid : 0, incr ? '+' : '-',
npages << PAGE_SHIFT,
- mm->locked_vm << PAGE_SHIFT,
+ atomic64_read(&mm->pinned_vm) << PAGE_SHIFT,
rlimit(RLIMIT_MEMLOCK));
- up_write(&mm->mmap_sem);

return ret;
}
@@ -133,7 +132,7 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
struct mm_iommu_table_group_mem_t **pmem)
{
struct mm_iommu_table_group_mem_t *mem;
- long i, j, ret = 0, locked_entries = 0;
+ long i, j, ret = 0, pinned_entries = 0;
unsigned int pageshift;
unsigned long flags;
unsigned long cur_ua;
@@ -154,11 +153,11 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
}

if (dev_hpa == MM_IOMMU_TABLE_INVALID_HPA) {
- ret = mm_iommu_adjust_locked_vm(mm, entries, true);
+ ret = mm_iommu_adjust_pinned_vm(mm, entries, true);
if (ret)
goto unlock_exit;

- locked_entries = entries;
+ pinned_entries = entries;
}

mem = kzalloc(sizeof(*mem), GFP_KERNEL);
@@ -252,8 +251,8 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
list_add_rcu(&mem->next, &mm->context.iommu_group_mem_list);

unlock_exit:
- if (locked_entries && ret)
- mm_iommu_adjust_locked_vm(mm, locked_entries, false);
+ if (pinned_entries && ret)
+ mm_iommu_adjust_pinned_vm(mm, pinned_entries, false);

mutex_unlock(&mem_list_mutex);

@@ -352,7 +351,7 @@ long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
mm_iommu_release(mem);

if (dev_hpa == MM_IOMMU_TABLE_INVALID_HPA)
- mm_iommu_adjust_locked_vm(mm, entries, false);
+ mm_iommu_adjust_pinned_vm(mm, entries, false);

unlock_exit:
mutex_unlock(&mem_list_mutex);
--
2.20.1
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