accel/tcg: Retry page_check_range() on itree.start inconsistency

[PATCH 0/1] accel/tcg: Retry page_check_range() on itree.start inconsistency

Ilya Leoshkevich posted 1 patch 2 weeks, 5 days ago

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git fetch https://github.com/patchew-project/qemu tags/patchew/20260706110330.4150026-1-iii@linux.ibm.com

Maintainers: Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>

accel/tcg/user-exec.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)

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[PATCH 0/1] accel/tcg: Retry page_check_range() on itree.start inconsistency

Posted by Ilya Leoshkevich 2 weeks, 5 days ago

Hi,

This is an attempt to improve the vma-pthread test situation sparked by
a bug report by wasmtime project. The patch doesn't fix all issues, but
it definitely makes things better and I think I understand what
particular thread interleaving leads to the issue (details are in the
commit message).

There is at least one other thing that I find suspicious about the
current code: page_check_range() fetches itree.last twice, and indeed,
using qatomic_read() there makes things even better, but still not
perfect, and I still cannot clearly elaborate what is the exact
interleaving with pageflags_set_clear() that causes a problem there, so
I'm not sending that one for now.

Best regards,
Ilya

Ilya Leoshkevich (1):
  accel/tcg: Retry page_check_range() on itree.start inconsistency

 accel/tcg/user-exec.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

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2.54.0