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Subject[PATCH 3/5] fpga/dlf/afu: 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 FPGA AFU
driver accounts 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>
---
drivers/fpga/dfl-afu-dma-region.c | 50 ++++++++++++++-----------------
1 file changed, 23 insertions(+), 27 deletions(-)

diff --git a/drivers/fpga/dfl-afu-dma-region.c b/drivers/fpga/dfl-afu-dma-region.c
index e18a786fc943..a9a6b317fe2e 100644
--- a/drivers/fpga/dfl-afu-dma-region.c
+++ b/drivers/fpga/dfl-afu-dma-region.c
@@ -32,47 +32,43 @@ void afu_dma_region_init(struct dfl_feature_platform_data *pdata)
}

/**
- * afu_dma_adjust_locked_vm - adjust locked memory
+ * afu_dma_adjust_pinned_vm - adjust pinned memory
* @dev: port device
* @npages: number of pages
- * @incr: increase or decrease locked memory
*
- * Increase or decrease the locked memory size with npages input.
+ * Increase or decrease the pinned memory size with npages input.
*
* Return 0 on success.
- * Return -ENOMEM if locked memory size is over the limit and no CAP_IPC_LOCK.
+ * Return -ENOMEM if pinned memory size is over the limit and no CAP_IPC_LOCK.
*/
-static int afu_dma_adjust_locked_vm(struct device *dev, long npages, bool incr)
+static int afu_dma_adjust_pinned_vm(struct device *dev, long pages)
{
- unsigned long locked, lock_limit;
+ unsigned long lock_limit;
+ s64 pinned_vm;
int ret = 0;

/* the task is exiting. */
- if (!current->mm)
+ if (!current->mm || !pages)
return 0;

- down_write(&current->mm->mmap_sem);
-
- if (incr) {
- locked = current->mm->locked_vm + npages;
+ if (pages > 0) {
lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-
- if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+ pinned_vm = atomic64_add_return(pages, &current->mm->pinned_vm);
+ if (pinned_vm > lock_limit && !capable(CAP_IPC_LOCK)) {
ret = -ENOMEM;
- else
- current->mm->locked_vm += npages;
+ atomic64_sub(pages, &current->mm->pinned_vm);
+ }
} else {
- if (WARN_ON_ONCE(npages > current->mm->locked_vm))
- npages = current->mm->locked_vm;
- current->mm->locked_vm -= npages;
+ pinned_vm = atomic64_read(&current->mm->pinned_vm);
+ if (WARN_ON_ONCE(pages > pinned_vm))
+ pages = pinned_vm;
+ atomic64_sub(pages, &current->mm->pinned_vm);
}

- dev_dbg(dev, "[%d] RLIMIT_MEMLOCK %c%ld %ld/%ld%s\n", current->pid,
- incr ? '+' : '-', npages << PAGE_SHIFT,
- current->mm->locked_vm << PAGE_SHIFT, rlimit(RLIMIT_MEMLOCK),
- ret ? "- exceeded" : "");
-
- up_write(&current->mm->mmap_sem);
+ dev_dbg(dev, "[%d] RLIMIT_MEMLOCK %c%ld %lld/%lu%s\n", current->pid,
+ (pages > 0) ? '+' : '-', pages << PAGE_SHIFT,
+ (s64)atomic64_read(&current->mm->pinned_vm) << PAGE_SHIFT,
+ rlimit(RLIMIT_MEMLOCK), ret ? "- exceeded" : "");

return ret;
}
@@ -92,7 +88,7 @@ static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
struct device *dev = &pdata->dev->dev;
int ret, pinned;

- ret = afu_dma_adjust_locked_vm(dev, npages, true);
+ ret = afu_dma_adjust_pinned_vm(dev, npages);
if (ret)
return ret;

@@ -121,7 +117,7 @@ static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
free_pages:
kfree(region->pages);
unlock_vm:
- afu_dma_adjust_locked_vm(dev, npages, false);
+ afu_dma_adjust_pinned_vm(dev, -npages);
return ret;
}

@@ -141,7 +137,7 @@ static void afu_dma_unpin_pages(struct dfl_feature_platform_data *pdata,

put_all_pages(region->pages, npages);
kfree(region->pages);
- afu_dma_adjust_locked_vm(dev, npages, false);
+ afu_dma_adjust_pinned_vm(dev, -npages);

dev_dbg(dev, "%ld pages unpinned\n", npages);
}
--
2.20.1
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