Re: [PATCH 00/16] memory: Stop piggybacking on memory region owners

[Peter Maydell <peter.maydell@linaro.org>]

On Mon, 1 Sept 2025 at 13:35, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Mon, 1 Sept 2025 at 07:11, Akihiko Odaki
> <odaki@rsg.ci.i.u-tokyo.ac.jp> wrote:
> >
> > Supersedes: https://lore.kernel.org/qemu-devel/20250828-san-v9-0-c0dff4b8a487@rsg.ci.i.u-tokyo.ac.jp/
> > ("[PATCH v9 0/2] Fix check-qtest-ppc64 sanitizer errors")
> >
> > MemoryRegions used to "piggyback" on their owners instead of using their
> > reference counters due to the circular dependencies between them, which
> > caused memory leak.
> >
> > I tried to fix it with "[PATCH v9 0/2] Fix check-qtest-ppc64 sanitizer
> > errors" but it resulted in a lengthy discussion; ultimately it is
> > attributed to the fact that "piggybacking" is hard to understand and
> > forces us design trade-offs. It was also insufficient because it only
> > deals with the container-subregion pattern and did not deal with DMA.
>
> Unlike Peter Xu's proposed patch and your v9 patch you reference
> above, with this series I still see leaks doing a 'make check'
> on an ASAN build of the Arm targets. Here's a sample leak
> detected during the device-introspect-test:

I should mention that I'm using an lsan-suppressions.txt file
with the following entries:

# This is a set of suppressions for LeakSanitizer; you can use it
# by setting
#   LSAN_OPTIONS="suppressions=/path/to/scripts/lsan-suppressions.txt"
# register_init_block API is busted
leak:register_init_block
leak:canfd_populate_regarray
# qtest-only leak, not very important
leak:qemu_irq_intercept_in
# this is maybe a leak caused by g_test_trap_subprocess():
# in the subprocess, the cleanup functions that are supposed to free
# memory don't get run for some reason.
leak:qos_traverse_graph

plus various leak fixes which I've sent out over the past week or two:

[PATCH 0/3] hw: Fix qemu_init_irq() leaks
 https://patchew.org/QEMU/20250821154053.2417090-1-peter.maydell@linaro.org/

[PATCH] hw/char/max78000_uart: Destroy FIFO on deinit
https://patchew.org/QEMU/20250821154358.2417744-1-peter.maydell@linaro.org/

[PATCH] hw/gpio/pca9554: Avoid leak in pca9554_set_pin()
https://patchew.org/QEMU/20250821154459.2417976-1-peter.maydell@linaro.org/

[PATCH 0/2] hw: fix some leaks in xlnx devices
https://patchew.org/QEMU/20250826174956.3010274-1-peter.maydell@linaro.org/

[PATCH] hw/arm/boot: Correctly free the MemoryDeviceInfoList
https://patchew.org/QEMU/20250901102214.3748011-1-peter.maydell@linaro.org/

and with those patches plus the lsan-suppressions file plus either
Peter Xu's patch or your v9 patch I get a clean 'make check' run.

thanks
-- PMM