16589 zfs: avoid kfpu use when panicking

Reviewed by: Marco van Wieringen <[email protected]> Reviewed by: Gordon Ross <[email protected]> Approved by: Dan McDonald <[email protected]>
oxidecomputer · Jun 4, 2024 · 4c827c3 · 4c827c3
1 parent 12b7c4c
commit 4c827c3
Showing 1 changed file with 10 additions and 0 deletions.
diff --git a/usr/src/uts/common/fs/zfs/sys/simd.h b/usr/src/uts/common/fs/zfs/sys/simd.h
@@ -11,6 +11,7 @@
 
 /*
  * Copyright 2020 Joyent, Inc.
+ * Copyright 2024 Oxide Computer Company
  */
 
 #ifndef _SIMD_H
@@ -25,6 +26,7 @@
 #ifdef _KERNEL
 #include <sys/x86_archext.h>
 #include <sys/archsystm.h>
+#include <sys/systm.h>
 #include <sys/kfpu.h>
 #include <sys/proc.h>
 #include <sys/disp.h>
@@ -35,6 +37,14 @@ kfpu_allowed(void)
 {
 	extern int zfs_fpu_enabled;
 
+	/*
+	 * When panicking, play it safe and avoid kfpu use. This gives the best
+	 * chance of being able to dump successfully, particularly if the panic
+	 * occured around an FPU context switch.
+	 */
+	if (panicstr != NULL)
+		return (0);
+
 	return (zfs_fpu_enabled != 0 ? 1 : 0);
 }