David,
KSPConvergedDefault() now takes a non-NULL context that must be provided.
I have attached a modified version of ex5f.F90 that demonstrates how it is
constructured before being passed to KSPSetConvergenceTest(). Barry
ex5f.F90
Description: Binary data
> On Jan 20, 2025, at 8:54 AM, Daniel Stone <daniel.st...@opengosim.com> wrote:
>
> Hello PETSc Community,
>
> I think I've found a bug -
>
> Go to $PETSC_DIR/src/ksp/ksp/tutorials/
>
> open ex5f.F90, and add the following line in MyKSPConverged(), say around
> line 336:
>
> call KSPConvergedDefault(ksp,n,rnorm,flag,dummy,ierr)
>
> It should make sense why someone would want to do this - within a definition
> of custom convergence behaviour, get the default convergence flags, and,
> based on certain conditions, overwrite it.
>
> Now, building and running the exercise, making sure to include the flag to
> use the custom convergence:
>
>
> boston@boston-SYS-540A-TR:~/DATA_DRIVE/PETSC_DIRS/petsc_3.22/src/ksp/ksp/tutorials$
> ./ex2f -my_ksp_convergence
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation,
> probably memory access out of range[...]
>
> From my debugging, the issue is at line 1520 of iterativ.c:
>
> KSPConvergedDefaultCtx *cctx = (KSPConvergedDefaultCtx *)ctx;
>
> Because a dummy is used for the context object, this cast fails (my debugger
> says "cannot access memory..." for cctx). Then the crash happens when trying
> to access members of cctx:
>
> if (cctx->convmaxits && n >= ksp->max_it) {
>
>
> I'm not sure how to fix it. Crucially, we must note that that this did work
> in older versions of PETSc - I can repeat this test in 3.19.1, for example,
> and it works fine - a debugger shows the cast succeeding and producing some
> defaulted version of the ctx object, the subsequent crash does not happen,
> etc.
>
> Does anybody have any advice for working around this for the time being? A
> piece of software I work with uses a custom ksp convergence test in the
> manner described above, and is only functional with older versions of petsc
> because of this.
> Like in ex2f, I have no need of the ctx object, and just as in ex2f, I use 0
> instead.
>
> Things I'll try next: defining a proper ctx object (I use 0, like in ex2f),
> or looking for some PETSC_NULL_CTX definition somewhere.
>
> Many Thanks,
>
> Daniel
>
>
>
