kern/162741: commit references a PR

[dfilter service]

The following reply was made to PR kern/162741; it has been noted by GNATS.

From: dfilter at FreeBSD.ORG (dfilter service)
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: kern/162741: commit references a PR
Date: Sat, 21 Jan 2012 07:57:38 +0000 (UTC)

 Author: alc
 Date: Sat Jan 21 07:57:27 2012
 New Revision: 230420
 URL: http://svn.freebsd.org/changeset/base/230420
 
 Log:
   MFC r226163, r228317, and r228324
     Fix the handling of an empty kmem map by sysctl_kmem_map_free().
   
     Eliminate the possibility of 32-bit arithmetic overflow in the
     calculation of vm_kmem_size that may occur if the system
     administrator has specified a vm.vm_kmem_size tunable value that
     exceeds the hard cap.
   
     Eliminate stale numbers from a comment.
   
   PR:		162741
 
 Modified:
   stable/7/sys/kern/kern_malloc.c
 Directory Properties:
   stable/7/sys/   (props changed)
   stable/7/sys/cddl/contrib/opensolaris/   (props changed)
   stable/7/sys/contrib/dev/acpica/   (props changed)
   stable/7/sys/contrib/pf/   (props changed)
 
 Modified: stable/7/sys/kern/kern_malloc.c
 ==============================================================================
 --- stable/7/sys/kern/kern_malloc.c	Sat Jan 21 07:21:44 2012	(r230419)
 +++ stable/7/sys/kern/kern_malloc.c	Sat Jan 21 07:57:27 2012	(r230420)
 @@ -258,8 +258,8 @@ sysctl_kmem_map_free(SYSCTL_HANDLER_ARGS
  	u_long size;
  
  	vm_map_lock_read(kmem_map);
 -	size = kmem_map->root != NULL ?
 -	    kmem_map->root->max_free : kmem_map->size;
 +	size = kmem_map->root != NULL ? kmem_map->root->max_free :
 +	    kmem_map->max_offset - kmem_map->min_offset;
  	vm_map_unlock_read(kmem_map);
  	return (sysctl_handle_long(oidp, &size, 0, req));
  }
 @@ -594,12 +594,9 @@ kmeminit(void *dummy)
  
  	/*
  	 * Try to auto-tune the kernel memory size, so that it is
 -	 * more applicable for a wider range of machine sizes.
 -	 * On an X86, a VM_KMEM_SIZE_SCALE value of 4 is good, while
 -	 * a VM_KMEM_SIZE of 12MB is a fair compromise.  The
 +	 * more applicable for a wider range of machine sizes.  The
  	 * VM_KMEM_SIZE_MAX is dependent on the maximum KVA space
 -	 * available, and on an X86 with a total KVA space of 256MB,
 -	 * try to keep VM_KMEM_SIZE_MAX at 80MB or below.
 +	 * available.
  	 *
  	 * Note that the kmem_map is also used by the zone allocator,
  	 * so make sure that there is enough space.
 @@ -640,11 +637,11 @@ kmeminit(void *dummy)
  	/*
  	 * Limit kmem virtual size to twice the physical memory.
  	 * This allows for kmem map sparseness, but limits the size
 -	 * to something sane. Be careful to not overflow the 32bit
 -	 * ints while doing the check.
 +	 * to something sane.  Be careful to not overflow the 32bit
 +	 * ints while doing the check or the adjustment.
  	 */
 -	if (((vm_kmem_size / 2) / PAGE_SIZE) > cnt.v_page_count)
 -		vm_kmem_size = 2 * cnt.v_page_count * PAGE_SIZE;
 +	if (vm_kmem_size / 2 / PAGE_SIZE > mem_size)
 +		vm_kmem_size = 2 * mem_size * PAGE_SIZE;
  
  	/*
  	 * Tune settings based on the kmem map's size at this time.
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