sci-libs/openblas: fix memory allocation issues

* Backport upstream fix to not spin in blas_memory_alloc on ENOMEM
  (bug #967251). Combined with the high defaults for NUM_PARALLEL and
  NUM_THREADS set by the ebuild, flexiblas configure would hang.

* Choose lower values for NUM_PARALLEL, NUM_THREADS on 32-bit arches
  (bug #967251).

* Document the current issue w/ overcommit (bug #967026).

Thank you to Anon Emuss for the detailed bug report and analysis.

Bug: https://bugs.gentoo.org/967026
Closes: https://bugs.gentoo.org/967251
Tested-by: Eli Schwartz <eschwartz@gentoo.org>
Signed-off-by: Sam James <sam@gentoo.org>

2 files changed, 71 insertions, 1 deletions

diff --git a/sci-libs/openblas/files/openblas-0.3.30-enomem-check.patch b/sci-libs/openblas/files/openblas-0.3.30-enomem-check.patch
new file mode 100644
index 000000000000..bf2e1d4035a8
--- /dev/null
+++ b/sci-libs/openblas/files/openblas-0.3.30-enomem-check.patch
@@ -0,0 +1,46 @@
+https://bugs.gentoo.org/967251
+https://github.com/OpenMathLib/OpenBLAS/issues/5289
+https://github.com/OpenMathLib/OpenBLAS/pull/5303
+
+From 31ef2cbbb353c1331a22ed4f909a6ffb5cc45b45 Mon Sep 17 00:00:00 2001
+From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
+Date: Fri, 13 Jun 2025 14:11:03 +0200
+Subject: [PATCH] Exit if memory allocation keeps failing, instead of looping
+ forever
+
+---
+ driver/others/memory.c | 13 +++++++++++--
+ 1 file changed, 11 insertions(+), 2 deletions(-)
+
+diff --git a/driver/others/memory.c b/driver/others/memory.c
+index c53e798bc1..c8415f348e 100644
+--- a/driver/others/memory.c
++++ b/driver/others/memory.c
+@@ -2922,6 +2922,7 @@ void *blas_memory_alloc(int procpos){
+   blas_unlock(&memory[position].lock);
+ #endif
+   if (!memory[position].addr) {
++    int failcount = 0;
+     do {
+ #ifdef DEBUG
+       printf("Allocation Start : %lx\n", base_address);
+@@ -2973,8 +2974,16 @@ void *blas_memory_alloc(int procpos){
+ #ifdef DEBUG
+       printf("  Success -> %08lx\n", map_address);
+ #endif
+-      if (((BLASLONG) map_address) == -1) base_address = 0UL;
+-
++      if (((BLASLONG) map_address) == -1) {
++	      base_address = 0UL;
++	      failcount++;
++	      if (failcount >10) {
++		      fprintf(stderr, "OpenBLAS error: Memory allocation still failed after 10 retries, giving up.\n");
++		      exit(1);
++	      }
++      } else {
++	      failcount = 0;
++      }
+       if (base_address) base_address += BUFFER_SIZE + FIXED_PAGESIZE;
+ 
+     } while ((BLASLONG)map_address == -1);
+
diff --git a/sci-libs/openblas/openblas-0.3.30-r4.ebuild b/sci-libs/openblas/openblas-0.3.30-r5.ebuild
index c6c72fa54cb9..ec3f26c2ff3a 100644
--- a/sci-libs/openblas/openblas-0.3.30-r4.ebuild
+++ b/sci-libs/openblas/openblas-0.3.30-r5.ebuild
@@ -36,6 +36,8 @@ PATCHES=(
 	"${FILESDIR}/${P}-lunar-lake.patch"
 	# https://github.com/OpenMathLib/OpenBLAS/pull/5360
 	"${FILESDIR}/${P}-arm-assembly.patch"
+	# https://github.com/OpenMathLib/OpenBLAS/pull/5303
+	"${FILESDIR}/${P}-enomem-check.patch"
 )
 
 pkg_pretend() {
@@ -109,7 +111,29 @@ src_configure() {
 		export DYNAMIC_ARCH=1 NO_AFFINITY=1 TARGET=GENERIC
 	fi
 
-	export NUM_PARALLEL=${OPENBLAS_NPARALLEL:-8} NUM_THREADS=${OPENBLAS_NTHREAD:-64}
+	case $(tc-get-ptr-size) in
+		4)
+			# NUM_BUFFERS = MAX(50, (2*NUM_PARALLEL*NUM_THREADS)
+			# BUFFER_SIZE = (16 << 20) (on x86)
+			# NUM_BUFFERS * BUFFER_SIZE is allocated and must be
+			# <4GiB on 32-bit arches (bug #967251).
+			#
+			# Scale down to 2*8*(16 << 20) = 256MiB for 32-bit
+			# arches. This avoids spinning in blas_memory_alloc
+			# which doesn't handle ENOMEM.
+			export NUM_PARALLEL=${OPENBLAS_NPARALLEL:-2}
+			export NUM_THREADS=${OPENBLAS_NTHREAD:-8}
+			;;
+		8)
+			# XXX: The current values here rely on overcommit
+			# for most systems (bug #967026).
+			export NUM_PARALLEL=${OPENBLAS_NPARALLEL:-8}
+			export NUM_THREADS=${OPENBLAS_NTHREAD:-64}
+			;;
+		*)
+			die "Unexpected tc-get-ptr-size. Please file a bug."
+			;;
+	esac
 
 	# Allow setting OPENBLAS_TARGET to override auto detection in case the
 	# toolchain is not enough to detect.