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#11844 closed defect (duplicate)

Race condition in building MPIR/yasm

Reported by:	vbraun	Owned by:	tbd
Priority:	critical	Milestone:	sage-duplicate/invalid/wontfix
Component:	packages: standard	Keywords:
Cc:	wbhart, leif	Merged in:
Authors:		Reviewers:	Leif Leonhardy
Report Upstream:	Fixed upstream, but not in a stable release.	Work issues:
Branch:		Commit:
Dependencies:	#11964, #11616	Stopgaps:

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Description (last modified by jdemeyer)

The included Yasm includes re2c which has a race condition during parallel build. See the upstream ticket for details:

http://tortall.lighthouseapp.com/projects/78676-yasm/tickets/238-parallel-make-fails

Fixed by #11616.

Change History (16)

comment:1 follow-up: ↓ 3 Changed 10 years ago by leif

Cc leif added
Priority changed from major to minor

Nice.

Which version of MPIR are you referring to?

(I don't know whether the yasm version in our "recent" MPIR packages ever changed at all, or which one we currently use.)

FWIW, IIRC we did a lot of massively parallel builds of MPIR 2.1.x, because of the race condition in MPIR's make install (fixed in MPIR 2.1.3 or .4), but never ran into an error caused by yasm.

comment:2 Changed 10 years ago by vbraun

Priority changed from minor to major

This is the mpir-1.2.2.p2.spkg from sage-4.7.2.alpha2. All versions of Yasm have the bug.

You probably didn't trip over the yasm bug because you were using a file system that allows you to open the same file multiple times for writing. Then you don't get the segfault, but you may get corrupted output. If you are extremely lucky gcc might even compile the clobbered output from re2c, and you'd just get mathematically wrong results for integer arithmetic.

comment:3 in reply to: ↑ 1 ; follow-up: ↓ 5 Changed 10 years ago by leif

Replying to leif:

FWIW, IIRC we did a lot of massively parallel builds of MPIR 2.1.x, because of the race condition in MPIR's make install (fixed in MPIR 2.1.3 or .4), but never ran into an error caused by yasm.

The latter is apparently fixed in MPIR 2.1.4.

comment:4 Changed 10 years ago by leif

Priority changed from major to critical

If it doesn't necessarily lead to a build error... :)

(I've also added a reference to this ticket on #11616.)

comment:5 in reply to: ↑ 3 Changed 10 years ago by leif

Replying to leif:

Replying to leif:

FWIW, IIRC we did a lot of massively parallel builds of MPIR 2.1.x, because of the race condition in MPIR's make install (fixed in MPIR 2.1.3 or .4), but never ran into an error caused by yasm.

The latter is apparently fixed in MPIR 2.1.4.

Not the latter, I meant MPIR's make install race condition. ;-)

comment:6 Changed 10 years ago by vbraun

Report Upstream changed from Workaround found; Bug reported upstream. to Fixed upstream, but not in a stable release.
Status changed from new to needs_review

This is now fixed upstream in

https://github.com/yasm/yasm/commit/2bd66514b6b100887c19d8598da38347b3cff40e

comment:7 Changed 10 years ago by leif

Wonder whether they can include the fix in MPIR 2.5.0 (which should already be right before the door).

I'll provide updated MPIR spkgs (at least an MPIR 2.1.3.p5 or 2.1.4.pX spkg, the others for #11616) fixing the need to specify ABI=32 on 32-bit operating systems running on 64-bit CPUs anyway, then I can include such a fix by a patch to upstream.

Note that the yasm guys do not check whether the call to tmpfile() succeeded, nor is the file opened in text mode as it was before. (The latter should be irrelevant on our supported platforms -- including Cygwin AFAIK. Microsoft deprecated tmpfile() anyway... ;-) )

comment:8 follow-up: ↓ 9 Changed 10 years ago by vbraun

Note that the yasm guys do not check whether the call to tmpfile() succeeded

In the unlikely case that tmpfile() can't find a unique file name, it'll return NULL so at least the yasm build will fail with a clean segfault. There are probably many other things that would go wrong at build time if tmpfile() fails...

comment:9 in reply to: ↑ 8 ; follow-up: ↓ 10 Changed 10 years ago by leif

Replying to vbraun:

Note that the yasm guys do not check whether the call to tmpfile() succeeded

In the unlikely case that tmpfile() can't find a unique file name, it'll return NULL

ERRORS
       EACCES Search permission denied for directory in file's path prefix.

       EEXIST Unable to generate a unique filename.

       EINTR  The call was interrupted by a signal.

       EMFILE Too many file descriptors in use by the process.

       ENFILE Too many files open in the system.

       ENOSPC There was no room in the directory to add the new filename.

       EROFS  Read-only file system.

So there are a couple of reasons why tmpfile()could fail (and these may be temporary, i.e., later calls at least from other processes may well succeed).

Letting re2c segfault is of course the pythonic way... ;-)