From: marc.zyngier@arm•com (Marc Zyngier)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 3/6] ARM: mm: Drop the lowmem watermark check from virt_addr_valid()
Date: Fri, 15 Nov 2013 11:48:05 +0000 [thread overview]
Message-ID: <528609F5.1020802@arm.com> (raw)
In-Reply-To: <20131115004034.GG20516@lvm>
On 15/11/13 00:40, Christoffer Dall wrote:
> On Thu, Nov 14, 2013 at 07:31:36PM -0500, Santosh Shilimkar wrote:
>> On Thursday 14 November 2013 07:22 PM, Christoffer Dall wrote:
>>> On Thu, Nov 14, 2013 at 02:37:43PM -0500, Santosh Shilimkar wrote:
>>>> Slab allocator can allocate memory beyond the lowmem watermark
>>>> which can lead to false failure of virt_addr_valid().
>>>>
>>>> So drop the check. The issue was seen with percpu_alloc()
>>>> in KVM code which was allocating memory beyond lowmem watermark.
>>>>
>>>> Am not completly sure whether this is the right fix and if it could
>>>> impact any other user of virt_addr_valid(). Without this fix as
>>>> pointed out the KVM init was failing in my testing.
>>>>
>>>> Cc: Christoffer Dall <christoffer.dall@linaro•org>
>>>> Cc: Marc Zyngier <marc.zyngier@arm•com>
>>>> Cc: Russell King <linux@arm•linux.org.uk>
>>>> Cc: Catalin Marinas <catalin.marinas@arm•com>
>>>> Cc: Will Deacon <will.deacon@arm•com>
>>>>
>>>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti•com>
>>>> ---
>>>> arch/arm/include/asm/memory.h | 3 +--
>>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
>>>> index 4dd2145..412da47 100644
>>>> --- a/arch/arm/include/asm/memory.h
>>>> +++ b/arch/arm/include/asm/memory.h
>>>> @@ -343,8 +343,7 @@ static inline __deprecated void *bus_to_virt(unsigned long x)
>>>> #define ARCH_PFN_OFFSET PHYS_PFN_OFFSET
>>>>
>>>> #define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
>>>> -#define virt_addr_valid(kaddr) ((unsigned long)(kaddr) >= PAGE_OFFSET && (unsigned long)(kaddr) < (unsigned long)high_memory)
>>>> -
>>>> +#define virt_addr_valid(kaddr) ((unsigned long)(kaddr) >= PAGE_OFFSET)
>>>> #endif
>>>>
>>>> #include <asm-generic/memory_model.h>
>>>> --
>>>> 1.7.9.5
>>>>
>>>
>>> This looks wrong to me. Check Documentation/arm/memory.txt, this would
>>> return true for the VMALLOC region, which would cause virt_to_phys to
>>> give you something invalid, which would be bad.
>>>
>> I also thought it might not be right fix and hence added a disclaimer
>> in the commit message ;-)
>>
> Yes I know, I'm not holding it against you ;)
>
> Not sure what the nicest fix is though. I think we can get away with
> the single page restriction per call for Hyp mappings for now. IIRC the
> Hyp code is still limited to be within a single page.
>
> Let's see what Marc has to say.
So that may change quite quickly. I already have additional code for
GICv3 in HYP, and I'd like to avoid putting restrictions that we'd have
a hard time removing later.
I'd like to try the approach I just sent out in a separate email first,
and if it can't be made to work, we can see how to either enforce a
single-page restriction or move the percpu stuff to kmalloc instead.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2013-11-15 11:48 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-14 19:37 [PATCH 0/6] ARM/AMR64: Few patches on kvm and mm code Santosh Shilimkar
2013-11-14 19:37 ` [PATCH 1/6] arm64: mm: Add __virt_to_idmap() to keep kvm build happy Santosh Shilimkar
2013-11-15 13:34 ` Catalin Marinas
2013-11-15 14:55 ` Santosh Shilimkar
2013-11-15 14:58 ` Catalin Marinas
2013-11-15 15:31 ` Santosh Shilimkar
2013-11-15 15:05 ` Marc Zyngier
2013-11-15 15:25 ` Santosh Shilimkar
2013-11-15 15:29 ` Marc Zyngier
2013-11-15 15:31 ` Catalin Marinas
2013-11-15 15:33 ` Santosh Shilimkar
2013-11-14 19:37 ` [PATCH 2/6] ARM: kvm: Use virt_to_idmap instead of virt_to_phys for idmap mappings Santosh Shilimkar
2013-11-15 0:12 ` Christoffer Dall
2013-11-14 19:37 ` [PATCH 3/6] ARM: mm: Drop the lowmem watermark check from virt_addr_valid() Santosh Shilimkar
2013-11-15 0:22 ` Christoffer Dall
2013-11-15 0:31 ` Santosh Shilimkar
2013-11-15 0:40 ` Christoffer Dall
2013-11-15 11:48 ` Marc Zyngier [this message]
2013-11-15 11:43 ` Marc Zyngier
2013-11-15 14:55 ` Santosh Shilimkar
2013-11-15 15:08 ` Marc Zyngier
2013-11-15 15:46 ` Christoffer Dall
2013-11-15 14:20 ` Russell King - ARM Linux
2013-11-15 15:40 ` Santosh Shilimkar
2013-11-14 19:37 ` [PATCH 4/6] arm64: " Santosh Shilimkar
2013-11-15 13:39 ` Catalin Marinas
2013-11-15 14:25 ` Marc Zyngier
2013-11-15 14:57 ` Santosh Shilimkar
2013-11-14 19:37 ` [PATCH 5/6] ARM: kvm: Use phys_addr_t instead of unsigned long in mm code Santosh Shilimkar
2013-11-15 0:09 ` Christoffer Dall
2013-11-15 0:10 ` Santosh Shilimkar
2013-11-15 11:58 ` Marc Zyngier
2013-11-14 19:37 ` [PATCH 6/6] ARM: kvm: TMP: Commit the hyp page tables to main memory Santosh Shilimkar
2013-11-14 22:36 ` Santosh Shilimkar
2013-11-15 0:11 ` Christoffer Dall
2013-11-15 0:15 ` Santosh Shilimkar
2013-11-15 0:27 ` Christoffer Dall
2013-11-15 0:36 ` Santosh Shilimkar
2013-11-15 0:42 ` Christoffer Dall
2013-11-15 1:19 ` Santosh Shilimkar
2013-11-15 1:35 ` Christoffer Dall
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