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Commit19d340a298upstream. When IORING_REGISTER_CLONE_BUFFERS is used to clone buffers from uring instance A to uring instance B, where A and B use different MMs for accounting, the accounting can go wrong: If uring instance A is closed before uring instance B, the pinned memory counters for uring instance B will be decremented, even though the pinned memory was originally accounted through uring instance A; so the MM of uring instance B can end up with negative locked memory. Cc: stable@vger.kernel.org Closes: https://lore.kernel.org/r/CAG48ez1zez4bdhmeGLEFxtbFADY4Czn3CV0u9d_TMcbvRA01bg@mail.gmail.com Fixes:7cc2a6eadc("io_uring: add IORING_REGISTER_COPY_BUFFERS method") Signed-off-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20250114-uring-check-accounting-v1-1-42e4145aa743@google.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>