[PATCH 1/2] fs/fuse, splice: use kvmalloc to allocate array of pipe_buffer structs.

From: Andrey Ryabinin
Date: Mon Jul 16 2018 - 12:02:38 EST


The amount of pipe->buffers is basically controlled by userspace by
fcntl(... F_SETPIPE_SZ ...) so it could be large. High order allocations
could be slow (if memory is heavily fragmented) or may fail if the order
is larger than PAGE_ALLOC_COSTLY_ORDER.

Since the 'bufs' doesn't need to be physically contiguous, use
the kvmalloc_array() to allocate memory. If high order
page isn't available, the kvamalloc*() will fallback to 0-order.

Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
---
fs/fuse/dev.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c6b88fa85e2e..74900571546d 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1362,8 +1362,8 @@ static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
if (!fud)
return -EPERM;

- bufs = kmalloc_array(pipe->buffers, sizeof(struct pipe_buffer),
- GFP_KERNEL);
+ bufs = kvmalloc_array(pipe->buffers, sizeof(struct pipe_buffer),
+ GFP_KERNEL);
if (!bufs)
return -ENOMEM;

@@ -1396,7 +1396,7 @@ static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
for (; page_nr < cs.nr_segs; page_nr++)
put_page(bufs[page_nr].page);

- kfree(bufs);
+ kvfree(bufs);
return ret;
}

@@ -1944,8 +1944,8 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
if (!fud)
return -EPERM;

- bufs = kmalloc_array(pipe->buffers, sizeof(struct pipe_buffer),
- GFP_KERNEL);
+ bufs = kvmalloc_array(pipe->buffers, sizeof(struct pipe_buffer),
+ GFP_KERNEL);
if (!bufs)
return -ENOMEM;

@@ -2003,7 +2003,7 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
pipe_buf_release(pipe, &bufs[idx]);

out:
- kfree(bufs);
+ kvfree(bufs);
return ret;
}

--
2.16.4