Re: sparc64 panics - ctx_free: context xxxx still active

On Sat, Apr 11, 2026 at 08:43:57PM +0200, Mark Kettenis wrote:
[...]
> Lightly tested by building some kernels and libc with make -j24.  I've
> never been able to trigger the db_enter() on my t5120, so I don't
> expect to ever hit this code myself.
> 
> ok?

A bit late to the party, yes, LGTM.

I'm restarting an experiment with your latest version and moving the
mtx_enter() call before the for loop.  The previous run didn't trigger
since Fri 10, 1pm, running perl subprocesses and building libc in a
loop.

> ? arch/sparc64/compile/GENERIC.MP/obj
> Index: arch/sparc64/sparc64/pmap.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/sparc64/sparc64/pmap.c,v
> diff -u -p -r1.127 pmap.c
> --- arch/sparc64/sparc64/pmap.c	14 Dec 2025 12:37:22 -0000	1.127
> +++ arch/sparc64/sparc64/pmap.c	11 Apr 2026 18:43:27 -0000
> @@ -2579,6 +2579,7 @@ ctx_free(struct pmap *pm)
>  {
>  	int oldctx;
>  #ifdef DIAGNOSTIC
> +	u_int64_t tag, data;
>  	int i;
>  #endif
>  	
> @@ -2597,10 +2598,25 @@ ctx_free(struct pmap *pm)
>  		db_enter();
>  	}
>  	for (i = 0; i < TSBENTS; i++) {
> -		if (TSB_TAG_CTX(tsb_dmmu[i].tag) == oldctx ||
> -		    TSB_TAG_CTX(tsb_immu[i].tag) == oldctx) {
> -			printf("ctx_free: context %d still active\n", oldctx);
> -			db_enter();
> +		tag = READ_ONCE(tsb_dmmu[i].tag);
> +                if (TSB_TAG_CTX(tag) == oldctx) {
> +			data = READ_ONCE(tsb_dmmu[i].data);
> +			atomic_cas_ulong((unsigned long *)&tsb_dmmu[i].tag,
> +			    tag, TSB_TAG_INVALID);
> +			printf("%s: context %d still active in DMMU TSB\n",
> +			    __func__, oldctx);
> +			printf("%s: tag 0x%016llx data 0x%016llx\n",
> +			    __func__, tag, data);
> +		}
> +		tag = READ_ONCE(tsb_immu[i].tag);
> +		if (TSB_TAG_CTX(tag) == oldctx) {
> +			data = READ_ONCE(tsb_immu[i].data);
> +			atomic_cas_ulong((unsigned long *)&tsb_immu[i].tag,
> +			    tag, TSB_TAG_INVALID);
> +			printf("%s: context %d still active in IMMU TSB\n",
> +			    __func__, oldctx);
> +			printf("%s: tag 0x%016llx data 0x%016llx\n",
> +			    __func__, tag, data);
>  		}
>  	}
>  #endif
> 

-- 
jca