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From: "Verma, Vishal L" <vishal.l.verma@intel.com>
To: "Jiang, Dave" <dave.jiang@intel.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
	"jack@suse.com" <jack@suse.com>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH] mm: fix BUG_ON() in vmf_insert_pfn_pud() from VM_MIXEDMAP removal
Date: Thu, 30 Aug 2018 20:28:02 +0000	[thread overview]
Message-ID: <1535660881.5995.74.camel@intel.com> (raw)
In-Reply-To: <153565957352.35524.1005746906902065126.stgit@djiang5-desk3.ch.intel.com>


On Thu, 2018-08-30 at 13:06 -0700, Dave Jiang wrote:
> It looks like I missed the PUD path when doing VM_MIXEDMAP removal.
> This can be triggered by:
> 1. Boot with memmap=4G!8G
> 2. build ndctl with destructive flag on
> 3. make TESTS=device-dax check
> 
> [  +0.000675] kernel BUG at mm/huge_memory.c:824!
> 
> Applying the same change that was applied to vmf_insert_pfn_pmd() in
> the
> original patch.
> 
> Fixes: e1fb4a08649 ("dax: remove VM_MIXEDMAP for fsdax and device
> dax")
> 
> Reported-by: Vishal Verma <vishal.l.verma@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  mm/huge_memory.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

This fixes the unit test failure, feel free to add:
Tested-by: Vishal Verma <vishal.l.verma@intel.com>

> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index c3bc7e9c9a2a..533f9b00147d 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -821,11 +821,11 @@ vm_fault_t vmf_insert_pfn_pud(struct
> vm_area_struct *vma, unsigned long addr,
>  	 * but we need to be consistent with PTEs and architectures
> that
>  	 * can't support a 'special' bit.
>  	 */
> -	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
> +	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
> +			!pfn_t_devmap(pfn));
>  	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
>  						(VM_PFNMAP|VM_MIXEDM
> AP));
>  	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma-
> >vm_flags));
> -	BUG_ON(!pfn_t_devmap(pfn));
>  
>  	if (addr < vma->vm_start || addr >= vma->vm_end)
>  		return VM_FAULT_SIGBUS;
> 
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  parent reply	other threads:[~2018-08-30 20:28 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-30 20:06 Dave Jiang
2018-08-30 20:12 ` Jeff Moyer
2018-08-30 20:28 ` Verma, Vishal L [this message]
2018-08-31 10:22 ` Jan Kara
  -- strict thread matches above, loose matches on Subject: below --
2018-08-30 20:05 Dave Jiang
2018-08-30 20:15 ` Dave Jiang

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