mpich-3.3b2 critical bug (deadlock) and patch

[Jed Brown]

MPICH 3.3b2 deadlocks when large tags are used (the issue was identified by the PETSc team, but it affects other packages). The fix is one line:

commit c597c8d79deea220a42751fda0f01ce70764c260
Author: Min Si <email address hidden>
Date: Wed Apr 18 10:15:25 2018 -0500

    ch3: Fix tag upper limit initialization

    The value of tag_ub is initialized in MPIR_Init_thread, but was
    incorrectly reset in ch3 device initialization. This patch fixes it.

    Signed-off-by: Ken Raffenetti <email address hidden>

diff --git a/src/mpid/ch3/src/mpid_init.c b/src/mpid/ch3/src/mpid_init.c
index f7664fd2e..298ef4bd5 100644
--- a/src/mpid/ch3/src/mpid_init.c
+++ b/src/mpid/ch3/src/mpid_init.c
@@ -157,7 +157,6 @@ int MPID_Init(int *argc, char ***argv, int requested, int *provided,
      * Set global process attributes. These can be overridden by the channel
      * if necessary.
      */
- MPIR_Process.attrs.tag_ub = INT_MAX;
     MPIR_Process.attrs.io = MPI_ANY_SOURCE;

     /*

See also https://github.com/pmodels/mpich/pull/3097/

I have confirmed that this bug is present in the current package distributed with Ubuntu 18.10.

I am aware of another bug that was fixed at a similar time and should also be patched on any Ubuntu releases that stick with mpich-3.3b2. (These are both fixed in mpich-3.3b3.)

commit 8edabc7373b82dd660019e53d246131765819294
Author: Rob Latham <email address hidden>
Date: Tue Apr 17 11:20:25 2018 -0500

    fix uninitialized variable

    Closes pmodels/mpich#2892

diff --git a/src/mpi/romio/adio/ad_nfs/ad_nfs_read.c b/src/mpi/romio/adio/ad_nfs/ad_nfs_read.c
index e01cc21b0..5b8f0b88f 100644
--- a/src/mpi/romio/adio/ad_nfs/ad_nfs_read.c
+++ b/src/mpi/romio/adio/ad_nfs/ad_nfs_read.c
@@ -158,7 +158,7 @@ void ADIOI_NFS_ReadStrided(ADIO_File fd, void *buf, int count,

     ADIOI_Flatlist_node *flat_buf, *flat_file;
     ADIO_Offset i_offset, new_brd_size, brd_size, size;
- int i, j, k, err, err_flag, st_index = 0;
+ int i, j, k, err, err_flag=0, st_index = 0;
     MPI_Count num, bufsize;
     int n_etypes_in_filetype;
     ADIO_Offset n_filetypes, etype_in_filetype, st_n_filetypes, size_in_filetype;

https://github.com/pmodels/mpich/commit/8edabc7373b82dd660019e53d246131765819294