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From: Dave Hansen <dave.hansen@intel.com>
To: Wupeng Ma <mawupeng1@huawei.com>,
	akpm@linux-foundation.org, dave.hansen@linux.intel.com,
	luto@kernel.org, peterz@infradead.org
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, bp@suse.de,
	toshi.kani@hp.com, suresh.b.siddha@intel.com,
	syzbot+5f488e922d047d8f00cc@syzkaller.appspotmail.com
Subject: Re: [RFC PATCH 1/1] x86/mm/pat: Clear VM_PAT if copy_p4d_range failed
Date: Wed, 22 Feb 2023 12:03:54 -0800	[thread overview]
Message-ID: <7016f30f-65dd-b1a1-a44a-fb7af689959b@intel.com> (raw)
In-Reply-To: <20230217025615.1595558-1-mawupeng1@huawei.com>

On 2/16/23 18:56, Wupeng Ma wrote:
> dup_mm
>   dup_mmap
>     copy_page_range
>       copy_p4d_range
>         copy_pud_range
>           copy_pmd_range
>             pmd_alloc
>               __pmd_alloc
>                 pmd_alloc_one
>                   page = alloc_pages(gfp, 0);
>                     if (!page)
>                       return NULL;
>     mmput
>         exit_mmap
>           unmap_vmas
>             unmap_single_vma
>               untrack_pfn
>                 follow_phys
>                   WARN_ON_ONCE(1);

What's the point of that warning in the first place?  I can certainly
imagine follow_phys() failing for sparse mappings, for instance.  Is
there some requirement that VM_PFNMAP can't be sparse?

  reply	other threads:[~2023-02-22 20:04 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-17  2:56 Wupeng Ma
2023-02-22 20:03 ` Dave Hansen [this message]
2023-03-02  3:47   ` mawupeng
2023-02-23 22:14 ` Andrew Morton
2023-02-24  1:15   ` mawupeng

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