Re: [PATCH 04/22] mm: use mm_is_kernel() in generic page table code

From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Kevin Brodsky <kevin.brodsky@arm.com>, linux-mm@kvack.org
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Subject: Re: [PATCH 04/22] mm: use mm_is_kernel() in generic page table code
Date: Tue, 21 Jul 2026 17:07:22 +0200	[thread overview]
Message-ID: <0d75daa4-a034-4094-bce5-57938d294163@kernel.org> (raw)
In-Reply-To: <02565237-d777-4c63-8b17-817df59feac4@arm.com>

On 7/16/26 11:35, Kevin Brodsky wrote:
> On 14/07/2026 16:03, Kevin Brodsky wrote:
>> diff --git a/mm/memory.c b/mm/memory.c
>> index d5e87624f692..c0244c0b0756 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -3394,13 +3394,13 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
>>  	spinlock_t *ptl;
>>  
>>  	if (create) {
>> - mapped_pte = pte = (mm == &init_mm) ?
>> + mapped_pte = pte = mm_is_kernel(mm) ?
>>  			pte_alloc_kernel_track(pmd, addr, mask) :
>>  			pte_alloc_map_lock(mm, pmd, addr, &ptl);
> 
> As noted by Sashiko, this is a little problematic because if
> apply_to_page_range() is called on efi_mm, then we will end up with
> __pte_alloc_kernel() taking the init_mm lock, since that's hardcoded.
> 
> That probably means we should pass the mm to __pte_alloc_kernel().

Agreed.

I guess we have to audit all existing init_mm usage?

-- 
Cheers,

David