On Mon, Feb 01, 2010 at 11:30:06PM -0500, Ted Unangst wrote:
quoted text
> I think this fixes the problem with sleeping and holding pseg_lck.
> 
> Index: uvm_extern.h
> ===================================================================
> RCS file: /home/tedu/cvs/src/sys/uvm/uvm_extern.h,v
> retrieving revision 1.82
> diff -u -r1.82 uvm_extern.h
> --- uvm_extern.h	11 Aug 2009 18:43:33 -0000	1.82
> +++ uvm_extern.h	2 Feb 2010 04:28:09 -0000
> @@ -517,8 +517,9 @@
>  				vaddr_t *, vsize_t, int,
>  				boolean_t, vm_map_t);
>  vaddr_t			uvm_km_valloc(vm_map_t, vsize_t);
> -vaddr_t			uvm_km_valloc_align(vm_map_t, vsize_t, vsize_t);
> +vaddr_t			uvm_km_valloc_try(vm_map_t, vsize_t);
>  vaddr_t			uvm_km_valloc_wait(vm_map_t, vsize_t);
> +vaddr_t			uvm_km_valloc_align(struct vm_map *, vsize_t, vsize_t, int);
>  vaddr_t			uvm_km_valloc_prefer_wait(vm_map_t, vsize_t,
>  					voff_t);
>  void			*uvm_km_getpage(boolean_t, int *);
> Index: uvm_km.c
> ===================================================================
> RCS file: /home/tedu/cvs/src/sys/uvm/uvm_km.c,v
> retrieving revision 1.75
> diff -u -r1.75 uvm_km.c
> --- uvm_km.c	25 Jul 2009 12:55:40 -0000	1.75
> +++ uvm_km.c	2 Feb 2010 04:27:35 -0000
> @@ -571,11 +571,17 @@
>  vaddr_t
>  uvm_km_valloc(struct vm_map *map, vsize_t size)
>  {
> -	return(uvm_km_valloc_align(map, size, 0));
> +	return(uvm_km_valloc_align(map, size, 0, 0));
>  }
>  
>  vaddr_t
> -uvm_km_valloc_align(struct vm_map *map, vsize_t size, vsize_t align)
> +uvm_km_valloc_try(struct vm_map *map, vsize_t size)
> +{
> +	return(uvm_km_valloc_align(map, size, 0, UVM_FLAG_TRYLOCK));
> +}
> +
> +vaddr_t
> +uvm_km_valloc_align(struct vm_map *map, vsize_t size, vsize_t align, int flags)
>  {
>  	vaddr_t kva;
>  	UVMHIST_FUNC("uvm_km_valloc"); UVMHIST_CALLED(maphist);
> @@ -592,7 +598,7 @@
>  
>  	if (__predict_false(uvm_map(map, &kva, size, uvm.kernel_object,
>  	    UVM_UNKNOWN_OFFSET, align, UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL,
> -	    UVM_INH_NONE, UVM_ADV_RANDOM, 0)) != 0)) {
> +	    UVM_INH_NONE, UVM_ADV_RANDOM, flags)) != 0)) {
>  		UVMHIST_LOG(maphist, "<- done (no VM)", 0,0,0,0);
>  		return(0);
>  	}
> Index: uvm_pager.c
> ===================================================================
> RCS file: /home/tedu/cvs/src/sys/uvm/uvm_pager.c,v
> retrieving revision 1.54
> diff -u -r1.54 uvm_pager.c
> --- uvm_pager.c	22 Jul 2009 21:05:37 -0000	1.54
> +++ uvm_pager.c	2 Feb 2010 04:23:57 -0000
> @@ -138,7 +138,7 @@
>  {
>  	KASSERT(pseg->start == 0);
>  	KASSERT(pseg->use == 0);
> -	pseg->start = uvm_km_valloc(kernel_map, MAX_PAGER_SEGS * MAXBSIZE);
> +	pseg->start = uvm_km_valloc_try(kernel_map, MAX_PAGER_SEGS * MAXBSIZE);


this doesn't take into account the fact that valloc_try may fail and
return 0.

The principle is good, but more is needed. Perhaps up to unlocking
everything and calling where we can sleep.

-0-
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