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From: Mike Rapoport <rppt@kernel.org>
To: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: dave.hansen@intel.com, luto@kernel.org, peterz@infradead.org,
	x86@kernel.org, akpm@linux-foundation.org, keescook@chromium.org,
	shakeelb@google.com, vbabka@suse.cz, linux-mm@kvack.org,
	linux-hardening@vger.kernel.org,
	kernel-hardening@lists.openwall.com, ira.weiny@intel.com,
	dan.j.williams@intel.com, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 10/19] x86/mm: Use alloc_table() for fill_pte(), etc
Date: Tue, 31 Aug 2021 11:47:49 +0300	[thread overview]
Message-ID: <YS3stfkkCLfqROx1@kernel.org> (raw)
In-Reply-To: <20210830235927.6443-11-rick.p.edgecombe@intel.com>

On Mon, Aug 30, 2021 at 04:59:18PM -0700, Rick Edgecombe wrote:
> fill_pte(), set_pte_vaddr(), etc allocate page tables with
> spp_getpage(). Use alloc_table() for these allocations in order to get
> tables from the cache of protected pages when needed.
 
I can't say I tracked all the users of set_pte_vaddr(), but I don't see a
fundamental reason why spp_getpage() would need GFP_ATOMIC. Even if there
is a caller of set_pte_vaddr() that cannot sleep, it seems that page tables
can be prepopulated so that set_pte_vaddr() will not need to allocate
anything.  

> Opportunistically, fix a stale comment.

Ack for this one :)
 
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
> ---
>  arch/x86/mm/init_64.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 3c0323ad99da..de5a785ee89f 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -220,16 +220,19 @@ static void sync_global_pgds(unsigned long start, unsigned long end)
>  
>  /*
>   * NOTE: This function is marked __ref because it calls __init function
> - * (alloc_bootmem_pages). It's safe to do it ONLY when after_bootmem == 0.
> + * (memblock_alloc). It's safe to do it ONLY when after_bootmem == 0.
>   */
>  static __ref void *spp_getpage(void)
>  {
>  	void *ptr;
>  
> -	if (after_bootmem)
> -		ptr = (void *) get_zeroed_page(GFP_ATOMIC);
> -	else
> +	if (after_bootmem) {
> +		struct page *page = alloc_table(GFP_ATOMIC | __GFP_ZERO);
> +
> +		ptr = page ? page_address(page) : NULL;
> +	} else {
>  		ptr = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
> +	}
>  
>  	if (!ptr || ((unsigned long)ptr & ~PAGE_MASK)) {
>  		panic("set_pte_phys: cannot allocate page data %s\n",
> -- 
> 2.17.1
> 

-- 
Sincerely yours,
Mike.

  reply	other threads:[~2021-08-31  8:48 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-30 23:59 [RFC PATCH v2 00/19] PKS write protected page tables Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 01/19] list: Support getting most recent element in list_lru Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 02/19] list: Support list head not in object for list_lru Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 03/19] x86/mm/cpa: Add grouped page allocations Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 04/19] mm: Explicitly zero page table lock ptr Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 05/19] x86, mm: Use cache of page tables Rick Edgecombe
2021-08-31  8:40   ` Mike Rapoport
2021-08-31 19:09     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 06/19] x86/mm/cpa: Add perm callbacks to grouped pages Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 07/19] x86/cpufeatures: Add feature for pks tables Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 08/19] x86/mm/cpa: Add get_grouped_page_atomic() Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 09/19] x86/mm: Support GFP_ATOMIC in alloc_table_node() Rick Edgecombe
2021-08-31  8:32   ` Mike Rapoport
2021-08-30 23:59 ` [RFC PATCH v2 10/19] x86/mm: Use alloc_table() for fill_pte(), etc Rick Edgecombe
2021-08-31  8:47   ` Mike Rapoport [this message]
2021-08-31 18:48     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 11/19] mm/sparsemem: Use alloc_table() for table allocations Rick Edgecombe
2021-08-31  8:55   ` Mike Rapoport
2021-08-31 18:25     ` Edgecombe, Rick P
2021-09-01  7:22       ` Mike Rapoport
2021-09-02 13:56         ` Vlastimil Babka
2021-08-30 23:59 ` [RFC PATCH v2 12/19] x86/mm: Use free_table in unmap path Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 13/19] mm/debug_vm_page_table: Use setters instead of WRITE_ONCE Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 14/19] x86/efi: Toggle table protections when copying Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 15/19] x86/mm/cpa: Add set_memory_pks() Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 16/19] x86/mm: Protect page tables with PKS Rick Edgecombe
2021-08-31  8:56   ` Mike Rapoport
2021-08-31 17:55     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 17/19] x86/mm/cpa: PKS protect direct map page tables Rick Edgecombe
2021-08-31 10:14   ` Mike Rapoport
2021-08-31 17:58     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 18/19] x86/mm: Add PKS table soft mode Rick Edgecombe
2021-08-31  3:49   ` Randy Dunlap
2021-08-31 17:55     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 19/19] x86/mm: Add PKS table debug checking Rick Edgecombe

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