[Qemu-devel] memory leak in block/xen_disk in qemu-3.x

[Olaf Hering]

What are the live time rules of ioreq->buf?

In my testing the memory usage of qemu is constantly growing from about
250MB to several GB after a few days.

Some debugging shows that ioreq_runio_qemu_aio() overwrites ioreq->buf,
which contributes to the leak. In addition, ioreq_reset() also just
globbers iorew->buf. While this was observed with a backport of xen_disk
changes to qemu-2.9, the code in xen_disk.c did not change in this
regard. I changed the code to call qemu_vfree(ioreq->buf) in the few
places that globber the pointer, that fixes the leak for me.

Right now neither qemu-3.0 nor 3.1 for me, so I can not test
qemu.git#master if it eventually behaves different than
qemu.git#stable-2.9+backport.

Olaf

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