Subject: Re: [PATCH] powerpc/mm: Drop VM_BUG_ON in get_region_id

From: Michael Ellerman <[email-masked]>
Date: Sat, 18 May 2019 21:15:04 +1000 (AEST)

On Wed, 2019-05-15 at 09:45:23 UTC, "Aneesh Kumar K.V" wrote:
> We can call get_region_id without validating the ea value. That means
> with a wrong ea value we hit the BUG as below.
> 
>  kernel BUG at arch/powerpc/include/asm/book3s/64/hash.h:129!
>  Oops: Exception in kernel mode, sig: 5 [#1]
>  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
>  CPU: 0 PID: 3937 Comm: access_tests Not tainted 5.1.0
>  ....
>  NIP [c00000000007ba20] do_slb_fault+0x70/0x320
>  LR [c00000000000896c] data_access_slb_common+0x15c/0x1a0
> 
> Fix this by removing the VM_BUG_ON. All callers make sure the returned region id
> is valid and error out otherwise.
> 
> Fixes: 0034d395f89d ("powerpc/mm/hash64: Map all the kernel regions in the same 0xc range")
> Signed-off-by: Aneesh Kumar K.V <[email-masked]>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/6457f42eb3f6e9552366631bd5aeb096

cheers