Subject: Re: crypto: sun4i-ss: error with kmap

From: Corentin Labbe <[email-masked]>
Date: Sat, 5 Dec 2020 19:43:34 +0100

On Fri, Dec 04, 2020 at 09:58:21PM +0100, Thomas Gleixner wrote:
> On Fri, Dec 04 2020 at 20:27, Corentin Labbe wrote:
> > On Fri, Dec 04, 2020 at 04:08:27PM +0100, Thomas Gleixner wrote:
> >> On Fri, Dec 04 2020 at 14:26, Corentin Labbe wrote:
> >> > On Fri, Dec 04, 2020 at 12:34:05AM +0100, Thomas Gleixner wrote:
> >> >> The unmap comes from sg_miter_stop() and looking at the previous
> >> >> map/unmap cycles there are never nested maps.
> >> >> 
> >> >> [  996.943030] cryptset-316       0d..4 73943317us : __kmap_local_pfn_prot: kmap_local_pfn: 1 ffefd000
> >> >> 
> >> >> is the first event which allocates a nested map. 
> >> >> 
> >> >> So something goes south either in sg_miter or in the crypto maze.
> >> >> 
> >> >> Enabling CONFIG_DEBUG_KMAP_LOCAL and function tracing might give us more clue.
> >> >
> >> > Done, http://kernel.montjoie.ovh/130466.log
> >> 
> >> Does not provide more information with the debug enabled. So can you
> >> please enable CONFIG_FUNCTION_TRACER and add 'ftrace=function' to the
> >> command line?
> >
> > Done, http://kernel.montjoie.ovh/130490.log
> 
> Aaargh. That overwrites everything while printing out that
> warning.
> 
> Can you please replace the debug patch with the one below and try again?
> That stops the trace right on the condition.
> 
> Thanks,
> 
>         tglx
> ---
> diff --git a/mm/highmem.c b/mm/highmem.c
> index b49364a306b8..8f8862f79d23 100644
> --- a/mm/highmem.c
> +++ b/mm/highmem.c
> @@ -485,6 +485,7 @@ static inline bool kmap_high_unmap_local(unsigned long vaddr)
>  {
>  #ifdef ARCH_NEEDS_KMAP_HIGH_GET
>  	if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
> +		trace_printk("kunmap_high: %lx\n", vaddr);
>  		kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
>  		return true;
>  	}
> @@ -520,6 +521,7 @@ void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
>  	preempt_disable();
>  	idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn);
>  	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
> +	trace_printk("kmap_local_pfn: %d %lx\n", idx, (unsigned long) vaddr);
>  	BUG_ON(!pte_none(*(kmap_pte - idx)));
>  	pteval = pfn_pte(pfn, prot);
>  	set_pte_at(&init_mm, vaddr, kmap_pte - idx, pteval);
> @@ -545,8 +547,10 @@ void *__kmap_local_page_prot(struct page *page, pgprot_t prot)
>  
>  	/* Try kmap_high_get() if architecture has it enabled */
>  	kmap = arch_kmap_local_high_get(page);
> -	if (kmap)
> +	if (kmap) {
> +		trace_printk("kmap_local_high_get: %lx\n", (unsigned long) kmap);
>  		return kmap;
> +	}
>  
>  	return __kmap_local_pfn_prot(page_to_pfn(page), prot);
>  }
> @@ -578,7 +582,11 @@ void kunmap_local_indexed(void *vaddr)
>  
>  	preempt_disable();
>  	idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr);
> -	WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
> +	trace_printk("kunmap_local: %i %lx\n", idx, (unsigned long) vaddr);
> +	if (addr != __fix_to_virt(FIX_KMAP_BEGIN + idx)) {
> +		tracing_off();
> +		BUG();
> +	}
>  
>  	arch_kmap_local_pre_unmap(addr);
>  	pte_clear(&init_mm, addr, kmap_pte - idx);
> 

Hello, the result could be found at http://kernel.montjoie.ovh/130739.log

Thanks

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