Date: Sat, 04 Oct 2014 17:53:26 +0900 (JST) From: Kohji Okuno <okuno.kohji@jp.panasonic.com> To: kostikbel@gmail.com Cc: stable@freebsd.org, freebsd-current@freebsd.org, okuno.kohji@jp.panasonic.com Subject: Re: About pmap_mapdev() & pmap_unmapdev() Message-ID: <20141004.175326.766405563100788209.okuno.kohji@jp.panasonic.com> In-Reply-To: <20141004082943.GN26076@kib.kiev.ua> References: <20141003215830.GK26076@kib.kiev.ua> <20141004.170036.336251378907610162.okuno.kohji@jp.panasonic.com> <20141004082943.GN26076@kib.kiev.ua>
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Hi, Konstantin,
> At the end of the mail is commit candidate. I did not even compiled this.
> Can you test and report back, please ?
Could you check the following?
(1) should use kernel_pmap->pm_stats.resident_count
^^^
I'm sorry. My patch was wrong.
(2) should use pmap_resident_count_inc() in amd64.
I will test, later.
In addtion, I have one question.
In current and 10-stable, is vm_map_delete() called by kva_free()?
If vm_map_delete() is called, this fix is needed in current and
10-stable, I think.
Regards,
Kohji Okuno
> On Sat, Oct 04, 2014 at 05:00:36PM +0900, Kohji Okuno wrote:
>> Hi, Konstantin,
>>
>> Thank you for your comment.
>> And, your change is better than mine.
> At the end of the mail is commit candidate. I did not even compiled this.
> Can you test and report back, please ?
>
>>
>> > Do you mean that this panic is related to missed pmap_remove() ?
>> > I doubt it, since pmap_mapdev() does not establish managed mappings.
>>
>> Yes, pmap_mapdev() does not establish managed mappings. But, if
>> kernel_pmap.pm_stats.resident_count is zero, then any managed pages
>> (for example pipe_map, exec_map, or etc.) are not able to change
>> unmanaged status, because pmap_remove() returns without calling
>> pmap_remove_pte().
>>
>> In this result, I encounterd the panic. Could you refer the following?
> Yes, kmem_back() indeed uses managed mapping.
>
> Index: amd64/amd64/pmap.c
> ===================================================================
> --- amd64/amd64/pmap.c (revision 272506)
> +++ amd64/amd64/pmap.c (working copy)
> @@ -5040,6 +5040,9 @@ pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, in
> pa = trunc_page(pa);
> for (tmpsize = 0; tmpsize < size; tmpsize += PAGE_SIZE)
> pmap_kenter_attr(va + tmpsize, pa + tmpsize, mode);
> + PMAP_LOCK(kernel_pmap);
> + kernel_pmap.pm_stats.resident_count += OFF_TO_IDX(size);
> + PMAP_UNLOCK(kernel_pmap);
> pmap_invalidate_range(kernel_pmap, va, va + tmpsize);
> pmap_invalidate_cache_range(va, va + tmpsize);
> return ((void *)(va + offset));
> Index: i386/i386/pmap.c
> ===================================================================
> --- i386/i386/pmap.c (revision 272506)
> +++ i386/i386/pmap.c (working copy)
> @@ -5066,10 +5066,14 @@ pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, in
> size = roundup(offset + size, PAGE_SIZE);
> pa = pa & PG_FRAME;
>
> - if (pa < KERNLOAD && pa + size <= KERNLOAD)
> + if (pa < KERNLOAD && pa + size <= KERNLOAD) {
> va = KERNBASE + pa;
> - else
> + } else {
> va = kmem_alloc_nofault(kernel_map, size);
> + PMAP_LOCK(kernel_pmap);
> + kernel_pmap.pm_stats.resident_count += OFF_TO_IDX(size);
> + PMAP_UNLOCK(kernel_pmap);
> + }
> if (!va)
> panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
>
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