From: Hou Tao <houtao1@huawei.com>
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@huawei.com>
---
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
On 8/31/24 5:37 PM, Hou Tao wrote:
> From: Hou Tao <houtao1@huawei.com>
>
> 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.
Actually, .wake_pending_and_unlock() is called under fiq->lock and
GFP_ATOMIC is requisite.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---
> 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) {
> /*
LGTM.
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
--
Thanks,
Jingbo
On 9/3/2024 5:34 PM, Jingbo Xu wrote:
>
> On 8/31/24 5:37 PM, Hou Tao wrote:
>> From: Hou Tao <houtao1@huawei.com>
>>
>> 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.
> Actually, .wake_pending_and_unlock() is called under fiq->lock and
> GFP_ATOMIC is requisite.
Er, but virtio_fs_wake_pending_and_unlock() unlocks fiq->lock before
queuing the request.
>
>
>> Signed-off-by: Hou Tao <houtao1@huawei.com>
>> ---
>> 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) {
>> /*
> LGTM.
>
> Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Thanks for the review.
>
>
On 9/4/24 11:53 AM, Hou Tao wrote:
>
>
> On 9/3/2024 5:34 PM, Jingbo Xu wrote:
>>
>> On 8/31/24 5:37 PM, Hou Tao wrote:
>>> From: Hou Tao <houtao1@huawei.com>
>>>
>>> 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.
>> Actually, .wake_pending_and_unlock() is called under fiq->lock and
>> GFP_ATOMIC is requisite.
>
> Er, but virtio_fs_wake_pending_and_unlock() unlocks fiq->lock before
> queuing the request.
Alright, I missed that :(
--
Thanks,
Jingbo
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