On Fri, May 22, 2026 at 03:47:31PM +0800, Jianping Li wrote: > > On 5/15/2026 9:38 PM, Dmitry Baryshkov wrote: > > On Fri, May 15, 2026 at 08:42:16PM +0800, Jianping Li wrote: > > > Allocating and freeing Audio PD memory from userspace is unsafe because > > > the kernel cannot reliably determine when the DSP has finished using the > > > memory. Userspace may free buffers while they are still in use by the DSP, > > > and remote free requests cannot be safely trusted. > > > > > > Allocate the entire Audio PD reserved-memory region upfront during rpmsg > > > probe and tie its lifetime to the rpmsg channel. This avoids userspace- > > > controlled alloc/free and ensures memory is reclaimed only when the DSP > > > shuts down. > > So, is this a bugfix or not? Is it possible to make the kernel misbehave > > without this patch being applied? > > Yes, this is a bug fix.
The tag, cc:stable, clear description as the bugfix? How would anybody guess if the patch is to be backported to earlier kernels or not? > Because currently after the audio PD requests to grow the heap, > the current kernel does not support shrinking the heap, which will all cause > memory leaks. > > The current modification is to allocate in advance and release uniformly, > which will avoid this error. > > Thanks, > Jianping. > > > > > > Signed-off-by: Jianping Li <[email protected]> > > > --- > > > drivers/misc/fastrpc.c | 107 +++++++++++++++++++---------------------- > > > 1 file changed, 49 insertions(+), 58 deletions(-) > > > -- With best wishes Dmitry
