From: Hou Tao <houtao1@xxxxxxxxxx>
When invoking virtio_fs_enqueue_req() through kworker, both the
allocation of the sg array and the bounce buffer still use GFP_ATOMIC.
Considering the size of the sg array may be greater than PAGE_SIZE, use
GFP_NOFS instead of GFP_ATOMIC to lower the possibility of memory
allocation failure and to avoid unnecessarily depleting the atomic
reserves. GFP_NOFS is not passed to virtio_fs_enqueue_req() directly,
GFP_KERNEL and memalloc_nofs_{save|restore} helpers are used instead.
It may seem OK to pass GFP_NOFS to virtio_fs_enqueue_req() as well when
queuing the request for the first time, but this is not the case. The
reason is that fuse_request_queue_background() may call
->queue_request_and_unlock() while holding fc->bg_lock, which is a
spin-lock. Therefore, still use GFP_ATOMIC for it.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
fs/fuse/virtio_fs.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 43d66ab5e891..9bc48b3ca384 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -95,7 +95,8 @@ struct virtio_fs_req_work {
};
static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
- struct fuse_req *req, bool in_flight);
+ struct fuse_req *req, bool in_flight,
+ gfp_t gfp);
static const struct constant_table dax_param_enums[] = {
{"always", FUSE_DAX_ALWAYS },
@@ -439,6 +440,8 @@ static void virtio_fs_request_dispatch_work(struct work_struct *work)
/* Dispatch pending requests */
while (1) {
+ unsigned int flags;
+
spin_lock(&fsvq->lock);
req = list_first_entry_or_null(&fsvq->queued_reqs,
struct fuse_req, list);
@@ -449,7 +452,9 @@ static void virtio_fs_request_dispatch_work(struct work_struct *work)
list_del_init(&req->list);
spin_unlock(&fsvq->lock);
- ret = virtio_fs_enqueue_req(fsvq, req, true);
+ flags = memalloc_nofs_save();
+ ret = virtio_fs_enqueue_req(fsvq, req, true, GFP_KERNEL);
+ memalloc_nofs_restore(flags);
if (ret < 0) {
if (ret == -ENOSPC) {
spin_lock(&fsvq->lock);
@@ -550,7 +555,7 @@ static void virtio_fs_hiprio_dispatch_work(struct work_struct *work)
}
/* Allocate and copy args into req->argbuf */
-static int copy_args_to_argbuf(struct fuse_req *req)
+static int copy_args_to_argbuf(struct fuse_req *req, gfp_t gfp)
{
struct fuse_args *args = req->args;
unsigned int offset = 0;
@@ -564,7 +569,7 @@ static int copy_args_to_argbuf(struct fuse_req *req)
len = fuse_len_args(num_in, (struct fuse_arg *) args->in_args) +
fuse_len_args(num_out, args->out_args);
- req->argbuf = kmalloc(len, GFP_ATOMIC);
+ req->argbuf = kmalloc(len, gfp);
if (!req->argbuf)
return -ENOMEM;
@@ -1239,7 +1244,8 @@ static unsigned int sg_init_fuse_args(struct scatterlist *sg,
/* Add a request to a virtqueue and kick the device */
static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
- struct fuse_req *req, bool in_flight)
+ struct fuse_req *req, bool in_flight,
+ gfp_t gfp)
{
/* requests need at least 4 elements */
struct scatterlist *stack_sgs[6];
@@ -1260,8 +1266,8 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
/* Does the sglist fit on the stack? */
total_sgs = sg_count_fuse_req(req);
if (total_sgs > ARRAY_SIZE(stack_sgs)) {
- sgs = kmalloc_array(total_sgs, sizeof(sgs[0]), GFP_ATOMIC);
- sg = kmalloc_array(total_sgs, sizeof(sg[0]), GFP_ATOMIC);
+ sgs = kmalloc_array(total_sgs, sizeof(sgs[0]), gfp);
+ sg = kmalloc_array(total_sgs, sizeof(sg[0]), gfp);
if (!sgs || !sg) {
ret = -ENOMEM;
goto out;
@@ -1269,7 +1275,7 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
}
/* Use a bounce buffer since stack args cannot be mapped */
- ret = copy_args_to_argbuf(req);
+ ret = copy_args_to_argbuf(req, gfp);
if (ret < 0)
goto out;
@@ -1367,7 +1373,7 @@ __releases(fiq->lock)
queue_id);
fsvq = &fs->vqs[queue_id];
- ret = virtio_fs_enqueue_req(fsvq, req, false);
+ ret = virtio_fs_enqueue_req(fsvq, req, false, GFP_ATOMIC);
if (ret < 0) {
if (ret == -ENOSPC) {
/*
--
2.29.2
