[PATCH v2 4/4] dma-buf: heaps: Fix shared system heap allocation rollback

[Jason Gunthorpe]

On Thu, Aug 20, 2026 at 04:00:33PM +0100, Steven Price wrote:
> If converting one of the allocated pages to shared memory fails, the
> cleanup path attempts to convert every page back to private memory.
> Pages after the failed page have not been converted yet, so attempting
> to convert them back can fail and cause otherwise reusable memory to be
> leaked.
> 
> Count the pages converted successfully and only convert those and the
> failed allocation back during cleanup. If converting the failed
> allocation back succeeds it can be freed safely; otherwise it is leaked
> because its state is unknown. Allocations that were not converted can be
> freed directly.
> 
> Fixes: 78b30c50a7ac ("dma-buf: heaps: system: add system_cc_shared heap for explicitly shared memory")
> Signed-off-by: Steven Price <steven.price at arm.com>
> ---
>  drivers/dma-buf/heaps/system_heap.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>

Jason