OS-4297 zero-sized allocations should be logged but not warned about

1 files changed, 13 insertions, 8 deletions

diff --git a/usr/src/uts/common/os/kmem.c b/usr/src/uts/common/os/kmem.c
index 37d28c42de..8872a02327 100644
--- a/usr/src/uts/common/os/kmem.c
+++ b/usr/src/uts/common/os/kmem.c
@@ -998,20 +998,22 @@ size_t kmem_transaction_log_size; /* transaction log size [2% of memory] */
 size_t kmem_content_log_size;	/* content log size [2% of memory] */
 size_t kmem_failure_log_size;	/* failure log [4 pages per CPU] */
 size_t kmem_slab_log_size;	/* slab create log [4 pages per CPU] */
+size_t kmem_zerosized_log_size;	/* zero-sized log [4 pages per CPU] */
 size_t kmem_content_maxsave = 256; /* KMF_CONTENTS max bytes to log */
 size_t kmem_lite_minsize = 0;	/* minimum buffer size for KMF_LITE */
 size_t kmem_lite_maxalign = 1024; /* maximum buffer alignment for KMF_LITE */
 int kmem_lite_pcs = 4;		/* number of PCs to store in KMF_LITE mode */
 size_t kmem_maxverify;		/* maximum bytes to inspect in debug routines */
 size_t kmem_minfirewall;	/* hardware-enforced redzone threshold */
-int kmem_warn_zerosized = 1;	/* whether to warn on zero-sized KM_SLEEP */
 
 #ifdef DEBUG
-int kmem_panic_zerosized = 1;	/* whether to panic on zero-sized KM_SLEEP */
+int kmem_warn_zerosized = 1;	/* whether to warn on zero-sized KM_SLEEP */
 #else
-int kmem_panic_zerosized = 0;	/* whether to panic on zero-sized KM_SLEEP */
+int kmem_warn_zerosized = 0;	/* whether to warn on zero-sized KM_SLEEP */
 #endif
 
+int kmem_panic_zerosized = 0;	/* whether to panic on zero-sized KM_SLEEP */
+
 #ifdef _LP64
 size_t	kmem_max_cached = KMEM_BIG_MAXBUF;	/* maximum kmem_alloc cache */
 #else
@@ -1151,6 +1153,7 @@ kmem_log_header_t	*kmem_transaction_log;
 kmem_log_header_t	*kmem_content_log;
 kmem_log_header_t	*kmem_failure_log;
 kmem_log_header_t	*kmem_slab_log;
+kmem_log_header_t	*kmem_zerosized_log;
 
 static int		kmem_lite_count; /* # of PCs in kmem_buftag_lite_t */
 
@@ -2961,18 +2964,20 @@ kmem_alloc(size_t size, int kmflag)
 			 * consider it to be deprecated behavior to allocate
 			 * 0 bytes.  If we have been configured to panic under
 			 * this condition, we panic; if to warn, we warn -- and
-			 * regardless, we bump a counter to at least indicate
-			 * that this condition has occurred.
+			 * regardless, we log to the kmem_zerosized_log that
+			 * that this condition has occurred (which gives us
+			 * enough information to be able to debug it).
 			 */
 			if (kmem_panic && kmem_panic_zerosized)
 				panic("attempted to kmem_alloc() size of 0");
 
 			if (kmem_warn_zerosized) {
 				cmn_err(CE_WARN, "kmem_alloc(): sleeping "
-				    "allocation with size of 0");
+				    "allocation with size of 0; "
+				    "see kmem_zerosized_log for details");
 			}
 
-			kmem_zerosized++;
+			kmem_log_event(kmem_zerosized_log, NULL, NULL, NULL);
 
 			return (NULL);
 		}
@@ -4499,8 +4504,8 @@ kmem_init(void)
 	}
 
 	kmem_failure_log = kmem_log_init(kmem_failure_log_size);
-
 	kmem_slab_log = kmem_log_init(kmem_slab_log_size);
+	kmem_zerosized_log = kmem_log_init(kmem_zerosized_log_size);
 
 	/*
 	 * Initialize STREAMS message caches so allocb() is available.