drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
Replace kfree() with kvfree() for memory allocated by kvmalloc().
Compile-tested only.
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
---
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c
index 9d06ff722fea..0dc4782df8c0 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c
@@ -325,7 +325,7 @@ r535_gsp_msgq_recv(struct nvkm_gsp *gsp, u32 gsp_rpc_len, int *retries)
rpc = r535_gsp_msgq_peek(gsp, sizeof(*rpc), info.retries);
if (IS_ERR_OR_NULL(rpc)) {
- kfree(buf);
+ kvfree(buf);
return rpc;
}
@@ -334,7 +334,7 @@ r535_gsp_msgq_recv(struct nvkm_gsp *gsp, u32 gsp_rpc_len, int *retries)
rpc = r535_gsp_msgq_recv_one_elem(gsp, &info);
if (IS_ERR_OR_NULL(rpc)) {
- kfree(buf);
+ kvfree(buf);
return rpc;
}
--
2.34.1> Replace … Is there a need to adjust also the following statement combination? https://elixir.bootlin.com/linux/v6.16/source/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c#L312-L314 … kvfree(info.gsp_rpc_buf); info.gsp_rpc_buf = NULL; return buf; … Regards, Markus
> Replace kfree() with kvfree() for memory allocated by kvmalloc(). * Would you like to improve the exception handling by using another goto chain? * How do you think about to increase the application of scope-based resource management? https://elixir.bootlin.com/linux/v6.16/source/include/linux/slab.h#L1081 Regards, Markus
On Mon, 11 Aug 2025 17:19:00 +0800
Qianfeng Rong <rongqianfeng@vivo.com> wrote:
Acked-by: Zhi Wang <zhiw@nvidia.com>
Please add a Fixes: tag.
> Replace kfree() with kvfree() for memory allocated by kvmalloc().
>
> Compile-tested only.
>
> Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
> ---
> drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c
> index 9d06ff722fea..0dc4782df8c0 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/rpc.c
> @@ -325,7 +325,7 @@ r535_gsp_msgq_recv(struct nvkm_gsp *gsp, u32 gsp_rpc_len, int *retries)
>
> rpc = r535_gsp_msgq_peek(gsp, sizeof(*rpc), info.retries);
> if (IS_ERR_OR_NULL(rpc)) {
> - kfree(buf);
> + kvfree(buf);
> return rpc;
> }
>
> @@ -334,7 +334,7 @@ r535_gsp_msgq_recv(struct nvkm_gsp *gsp, u32 gsp_rpc_len, int *retries)
>
> rpc = r535_gsp_msgq_recv_one_elem(gsp, &info);
> if (IS_ERR_OR_NULL(rpc)) {
> - kfree(buf);
> + kvfree(buf);
> return rpc;
> }
>
On Wed Aug 13, 2025 at 12:46 PM CEST, Zhi Wang wrote: > On Mon, 11 Aug 2025 17:19:00 +0800 > Qianfeng Rong <rongqianfeng@vivo.com> wrote: > > Acked-by: Zhi Wang <zhiw@nvidia.com> > > Please add a Fixes: tag. And please also add "Cc: stable@vger.kernel.org", thanks!
在 2025/8/13 19:01, Danilo Krummrich 写道: > [You don't often get email from dakr@kernel.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] > > On Wed Aug 13, 2025 at 12:46 PM CEST, Zhi Wang wrote: >> On Mon, 11 Aug 2025 17:19:00 +0800 >> Qianfeng Rong <rongqianfeng@vivo.com> wrote: >> >> Acked-by: Zhi Wang <zhiw@nvidia.com> >> >> Please add a Fixes: tag. > And please also add "Cc: stable@vger.kernel.org", thanks! Ok, Will do in the next version.
On Mon, 2025-08-11 at 17:19 +0800, Qianfeng Rong wrote:
> Replace kfree() with kvfree() for memory allocated by kvmalloc().
>
> Compile-tested only.
>
> Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Reviewed-by: Timur Tabi <ttabi@nvidia.com>
This does fix a real bug.
However, I think the real problem is that it's really confusing that
r535_gsp_msgq_recv_one_elem(gsp, &info) returns info.gsp_rpc_buf instead of just success/failure.
r535_gsp_msgq_recv() does this:
buf = kvmalloc(max_t(u32, rpc->length, expected), GFP_KERNEL);
...
info.gsp_rpc_buf = buf;
...
buf = r535_gsp_msgq_recv_one_elem(gsp, &info);
You wouldn't know it, but this does not change the value of 'buf' unless
r535_gsp_msgq_recv_one_elem() fails. If it does fail, the code does this:
if (IS_ERR(buf)) {
kvfree(info.gsp_rpc_buf);
It would be a lot clearer if we could kvfree(buf) here, but we can't because 'buf' no longer points
to the buffer, even though the buffer still exists.
On 13/08/2025 1.52, Timur Tabi wrote:
> On Mon, 2025-08-11 at 17:19 +0800, Qianfeng Rong wrote:
>> Replace kfree() with kvfree() for memory allocated by kvmalloc().
>>
>> Compile-tested only.
>>
>> Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
>
> Reviewed-by: Timur Tabi <ttabi@nvidia.com>
>
> This does fix a real bug.
>
Agree with the coding details.
I felt the core issue is that GSP RPC lifecycle management in NVKM is
not handled cleanly. For example, the caller’s RPC buffer is freed
silently in the receive path, and a new buffer is allocated and returned
without explicit coordination.
Introducing large GSP RPCs - such as factoring out
r535_gsp_msgq_recv_one_elem() - only makes this flaw more apparent, and
even the refactoring process is cumbersome and tricky.
Ideally, there should be a clear ownership and lifecycle flow between
the caller and the GSP RPC routines: the caller allocates and frees the
RPC buffer, while the low-level routines focus solely on send/receive
operations. r535_gsp_msgq_recv_one_elem() is just on its half way.
Z.
> However, I think the real problem is that it's really confusing that
> r535_gsp_msgq_recv_one_elem(gsp, &info) returns info.gsp_rpc_buf instead of just success/failure.
> r535_gsp_msgq_recv() does this:
>
> buf = kvmalloc(max_t(u32, rpc->length, expected), GFP_KERNEL);
> ...
> info.gsp_rpc_buf = buf;
> ...
> buf = r535_gsp_msgq_recv_one_elem(gsp, &info);
>
> You wouldn't know it, but this does not change the value of 'buf' unless
> r535_gsp_msgq_recv_one_elem() fails. If it does fail, the code does this:
>
> if (IS_ERR(buf)) {
> kvfree(info.gsp_rpc_buf);
>
> It would be a lot clearer if we could kvfree(buf) here, but we can't because 'buf' no longer points
> to the buffer, even though the buffer still exists.
>
>
On Wed Aug 13, 2025 at 12:52 AM CEST, Timur Tabi wrote:
> On Mon, 2025-08-11 at 17:19 +0800, Qianfeng Rong wrote:
>> Replace kfree() with kvfree() for memory allocated by kvmalloc().
>>
>> Compile-tested only.
>>
>> Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
>
> Reviewed-by: Timur Tabi <ttabi@nvidia.com>
>
> This does fix a real bug.
>
> However, I think the real problem is that it's really confusing that
> r535_gsp_msgq_recv_one_elem(gsp, &info) returns info.gsp_rpc_buf instead of just success/failure.
> r535_gsp_msgq_recv() does this:
>
> buf = kvmalloc(max_t(u32, rpc->length, expected), GFP_KERNEL);
> ...
> info.gsp_rpc_buf = buf;
> ...
> buf = r535_gsp_msgq_recv_one_elem(gsp, &info);
>
> You wouldn't know it, but this does not change the value of 'buf' unless
> r535_gsp_msgq_recv_one_elem() fails. If it does fail, the code does this:
Ick! That makes no sense, r535_gsp_msgq_recv_one_elem() should just return an
int and we shouldn't overwrite buf -- that's a footgun.
> if (IS_ERR(buf)) {
> kvfree(info.gsp_rpc_buf);
Should just be
if (ret) {
kvfree(buf);
return ERR_PTR(ret);
}
It also doesn't need the info.gsp_rpc_buf = NULL; assignment, info is local
anyways.
> It would be a lot clearer if we could kvfree(buf) here, but we can't because 'buf' no longer points
> to the buffer, even though the buffer still exists.
Agreed.
Zhi, Timur do you want to send a follow-up patch for this?
On Wed, 2025-08-13 at 13:00 +0200, Danilo Krummrich wrote: > > It would be a lot clearer if we could kvfree(buf) here, but we can't because 'buf' no longer > > points > > to the buffer, even though the buffer still exists. > > Agreed. > > Zhi, Timur do you want to send a follow-up patch for this? Yes, I'll send a patch this week that sits on top of Qianfeng's patch.
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