linux-kernel - Re: [PATCH v9 10/14] khugepaged: allow khugepaged to check all anonymous mTHP orders

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3b8d32dd-9d40-44b1-a0ab-8185073b9072@redhat.com>
Date: Wed, 16 Jul 2025 17:28:40 +0200
From: David Hildenbrand <david@...hat.com>
To: Nico Pache <npache@...hat.com>, linux-mm@...ck.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org
Cc: ziy@...dia.com, baolin.wang@...ux.alibaba.com,
 lorenzo.stoakes@...cle.com, Liam.Howlett@...cle.com, ryan.roberts@....com,
 dev.jain@....com, corbet@....net, rostedt@...dmis.org, mhiramat@...nel.org,
 mathieu.desnoyers@...icios.com, akpm@...ux-foundation.org,
 baohua@...nel.org, willy@...radead.org, peterx@...hat.com,
 wangkefeng.wang@...wei.com, usamaarif642@...il.com, sunnanyong@...wei.com,
 vishal.moola@...il.com, thomas.hellstrom@...ux.intel.com,
 yang@...amperecomputing.com, kirill.shutemov@...ux.intel.com,
 aarcange@...hat.com, raquini@...hat.com, anshuman.khandual@....com,
 catalin.marinas@....com, tiwai@...e.de, will@...nel.org,
 dave.hansen@...ux.intel.com, jack@...e.cz, cl@...two.org,
 jglisse@...gle.com, surenb@...gle.com, zokeefe@...gle.com,
 hannes@...xchg.org, rientjes@...gle.com, mhocko@...e.com,
 rdunlap@...radead.org, hughd@...gle.com
Subject: Re: [PATCH v9 10/14] khugepaged: allow khugepaged to check all
 anonymous mTHP orders

On 14.07.25 02:32, Nico Pache wrote:
> From: Baolin Wang <baolin.wang@...ux.alibaba.com>

Should the subject better be

"mm/khugepaged: enable collapsing mTHPs even when PMD THPs are disabled"

(in general, I assume all subjects should be prefixed by "mm/khugepaged:")

> 
> We have now allowed mTHP collapse, but thp_vma_allowable_order() still only
> checks if the PMD-sized mTHP is allowed to collapse. This prevents scanning
> and collapsing of 64K mTHP when only 64K mTHP is enabled. Thus, we should
> modify the checks to allow all large orders of anonymous mTHP.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> Signed-off-by: Nico Pache <npache@...hat.com>
> ---
>   mm/khugepaged.c | 13 +++++++++----
>   1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 7a9c4edf0e23..3772dc0d78ea 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -491,8 +491,11 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
>   {
>   	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
>   	    hugepage_pmd_enabled()) {
> -		if (thp_vma_allowable_order(vma, vm_flags, TVA_ENFORCE_SYSFS,
> -					    PMD_ORDER))
> +		unsigned long orders = vma_is_anonymous(vma) ?
> +					THP_ORDERS_ALL_ANON : BIT(PMD_ORDER);
> +
> +		if (thp_vma_allowable_orders(vma, vm_flags, TVA_ENFORCE_SYSFS,
> +					    orders))
>   			__khugepaged_enter(vma->vm_mm);
>   	}
>   }
> @@ -2624,6 +2627,8 @@ static unsigned int collapse_scan_mm_slot(unsigned int pages, int *result,
>   
>   	vma_iter_init(&vmi, mm, khugepaged_scan.address);
>   	for_each_vma(vmi, vma) {
> +		unsigned long orders = vma_is_anonymous(vma) ?
> +					THP_ORDERS_ALL_ANON : BIT(PMD_ORDER);
>   		unsigned long hstart, hend;
>   
>   		cond_resched();
> @@ -2631,8 +2636,8 @@ static unsigned int collapse_scan_mm_slot(unsigned int pages, int *result,
>   			progress++;
>   			break;
>   		}
> -		if (!thp_vma_allowable_order(vma, vma->vm_flags,
> -					TVA_ENFORCE_SYSFS, PMD_ORDER)) {
> +		if (!thp_vma_allowable_orders(vma, vma->vm_flags,
> +			TVA_ENFORCE_SYSFS, orders)) {
>   skip:
>   			progress++;
>   			continue;

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb