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Re: [PATCH v1 3/3] util/oslib-posix: Support concurrent os_mem_prealloc(
Re: [PATCH v1 3/3] util/oslib-posix: Support concurrent os_mem_prealloc() invocation
Tue, 20 Jul 2021 16:35:59 +0200
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Of course with the madvise impl we're bypassing the SIGBUS
dance entirely. This is good for people with new kernels,
but is this SIGBUS stuff safe for older kernels ?
It remains broken with old kernels I guess. There isn't too much that we can
do: disabling prealloc=on once the VM is running breaks existing use cases.
Ok, while refactoring this, could you add a scary warning next to the
sigaction calls mentioning that this code is not likely to play well
with qemu's other handling of sigbus, as a reminder to future reviewers.
Fortunately, running into that race seems to be rare, at least I never hear
The failure mode is likely to be silent or easily mis-interpreted
Is there any value in emitting a one-time per process warning message
on stderr if we take the old codepath post-startup ?
Will look into emitting a warning when running this code while the VM is
already running. (hope it won't be too ugly to have vm state checks in
David / dhildenb
Re: [PATCH v1 0/3] util/oslib-posix: Support MADV_POPULATE_WRITE for os_mem_prealloc(), Pankaj Gupta, 2021/07/20
Re: [PATCH v1 0/3] util/oslib-posix: Support MADV_POPULATE_WRITE for os_mem_prealloc(), Daniel P . Berrangé, 2021/07/20