*** This bug is a duplicate of bug 1572624 ***
https://bugs.launchpad.net/bugs/1572624
Hi,
Apologies for the confusion w/ the bug bridge; it has been reported.
LP 1580557 and LP 1580560 are the same bug (previously marked as a dup,
but removed later).
It seems the invalidation of this one didn't quite work.
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https://bugs.launchpad.net/bugs/1580557
Title:
Backport patch to abort syscalls in active transactions
Status in linux package in Ubuntu:
Triaged
Bug description:
== Comment: #0 - Tulio Magno Quites Machado Filho - 2016-02-23 12:47:09 ==
---Problem Description---
This is happening on Ubuntu 14.04.3.
User is creating stack structure using C++ transactional memory extension:
int Pop(int)
{
int ret = 0;
__transaction_atomic
{
if(!stack_.empty())
{
ret = stack_.top();
stack_.pop();
} else
ret = -1;
}
return ret;
}
While evaluating if(!stack_.empty()), this code calls a libitm function (GCC
code), which calls malloc (glibc code) which ends up calling futex (a syscall).
A syscall inside a transaction is forbidden by the kernel, but there is
nothing the user can do to avoid this syscall.
This will hang the user application inside the malloc(), which would
be waiting for the futex to return.
Ubuntu 14.04 provides glibc 2.19, which is too old to know about HTM.
And this is probably happening with other libraries as well.
Backporting commit b4b56f9e would solve this issue.
---uname output---
Linux 3.13.0-66-generic #108-Ubuntu SMP Wed Oct 7 16:06:09 UTC 2015 ppc64le
ppc64le ppc64le GNU/Linux
---Steps to Reproduce---
Start a transaction, make a syscall.
== Comment: #1 - Wei Guo - 2016-02-24 02:33:03 ==
I already verfied that kernel with patch b4b56f9e (on Ubuntu14.04) will work.
== Comment: #2 - Wei Guo - 2016-02-26 04:20:37 ==
Backport patch for commit b4b56f9e is attached. The patch is based on tag
Ubuntu-lts-3.19.0-25.26_14.04.1.
Tested based on Ubuntu 14.04.4 LTS ( 3.19.0-25-generic).
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