svn commit: r292117 - in head/sys: kern vm

[Mark Johnston]

Author: markj
Date: Fri Dec 11 20:05:07 2015
New Revision: 292117
URL: https://svnweb.freebsd.org/changeset/base/292117

Log:
  Don't make assertions about td_critnest when the scheduler is stopped.
  
  A panicking thread always executes with a critical section held, so any
  attempt to allocate or free memory while dumping will otherwise cause a
  second panic. This can occur, for example, if xpt_polled_action() completes
  non-dump I/O that was pending at the time of the panic. The fact that this
  can occur is itself a bug, but asserting in this case does little but
  reduce the reliability of kernel dumps.
  
  Suggested by:	kib
  Reported by:	pho

Modified:
  head/sys/kern/kern_malloc.c
  head/sys/vm/uma_core.c

Modified: head/sys/kern/kern_malloc.c
==============================================================================
--- head/sys/kern/kern_malloc.c	Fri Dec 11 18:47:41 2015	(r292116)
+++ head/sys/kern/kern_malloc.c	Fri Dec 11 20:05:07 2015	(r292117)
@@ -475,8 +475,7 @@ malloc(unsigned long size, struct malloc
 	if (flags & M_WAITOK)
 		KASSERT(curthread->td_intr_nesting_level == 0,
 		   ("malloc(M_WAITOK) in interrupt context"));
-
-	KASSERT(curthread->td_critnest == 0,
+	KASSERT(curthread->td_critnest == 0 || SCHEDULER_STOPPED(),
 	    ("malloc: called with spinlock or critical section held"));
 
 #ifdef DEBUG_MEMGUARD
@@ -544,8 +543,7 @@ free(void *addr, struct malloc_type *mtp
 	u_long size;
 
 	KASSERT(mtp->ks_magic == M_MAGIC, ("free: bad malloc type magic"));
-
-	KASSERT(curthread->td_critnest == 0,
+	KASSERT(curthread->td_critnest == 0 || SCHEDULER_STOPPED(),
 	    ("free: called with spinlock or critical section held"));
 
 	/* free(NULL, ...) does nothing */
@@ -610,8 +608,7 @@ realloc(void *addr, unsigned long size, 
 
 	KASSERT(mtp->ks_magic == M_MAGIC,
 	    ("realloc: bad malloc type magic"));
-
-	KASSERT(curthread->td_critnest == 0,
+	KASSERT(curthread->td_critnest == 0 || SCHEDULER_STOPPED(),
 	    ("realloc: called with spinlock or critical section held"));
 
 	/* realloc(NULL, ...) is equivalent to malloc(...) */

Modified: head/sys/vm/uma_core.c
==============================================================================
--- head/sys/vm/uma_core.c	Fri Dec 11 18:47:41 2015	(r292116)
+++ head/sys/vm/uma_core.c	Fri Dec 11 20:05:07 2015	(r292117)
@@ -2149,8 +2149,7 @@ uma_zalloc_arg(uma_zone_t zone, void *ud
 		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
 		    "uma_zalloc_arg: zone \"%s\"", zone->uz_name);
 	}
-
-	KASSERT(curthread->td_critnest == 0,
+	KASSERT(curthread->td_critnest == 0 || SCHEDULER_STOPPED(),
 	    ("uma_zalloc_arg: called with spinlock or critical section held"));
 
 #ifdef DEBUG_MEMGUARD
@@ -2690,7 +2689,7 @@ uma_zfree_arg(uma_zone_t zone, void *ite
 	CTR2(KTR_UMA, "uma_zfree_arg thread %x zone %s", curthread,
 	    zone->uz_name);
 
-	KASSERT(curthread->td_critnest == 0,
+	KASSERT(curthread->td_critnest == 0 || SCHEDULER_STOPPED(),
 	    ("uma_zfree_arg: called with spinlock or critical section held"));
 
         /* uma_zfree(..., NULL) does nothing, to match free(9). */