linux-kernel - Re: [PATCH v10 03/13] khugepaged: generalize hugepage_vma

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] [day] [month] [year] [list]

Message-ID: <20250821034153.uyxjy5yvxx5no5sf@master>
Date: Thu, 21 Aug 2025 03:41:53 +0000
From: Wei Yang <richard.weiyang@...il.com>
To: Nico Pache <npache@...hat.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, linux-mm@...ck.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org, david@...hat.com,
	ziy@...dia.com, baolin.wang@...ux.alibaba.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 v10 03/13] khugepaged: generalize hugepage_vma_revalidate
 for mTHP support

On Wed, Aug 20, 2025 at 09:40:40AM -0600, Nico Pache wrote:
[...]
>>
>> >       if (!thp_vma_suitable_order(vma, address, PMD_ORDER))
>> >               return SCAN_ADDRESS_RANGE;
>> > -     if (!thp_vma_allowable_order(vma, vma->vm_flags, type, PMD_ORDER))
>> > +     if (!thp_vma_allowable_orders(vma, vma->vm_flags, type, orders))
>> >               return SCAN_VMA_CHECK;
>> >       /*
>> >        * Anon VMA expected, the address may be unmapped then
>> > @@ -1134,7 +1135,8 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
>> >               goto out_nolock;
>> >
>> >       mmap_read_lock(mm);
>> > -     result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
>> > +     result = hugepage_vma_revalidate(mm, address, true, &vma, cc,
>> > +                                      BIT(HPAGE_PMD_ORDER));
>>
>> Shouldn't this be PMD order? Seems equivalent.
>Yeah i'm actually not sure why we have both... they seem to be the
>same thing, but perhaps there is some reason for having two...

I am confused with these two, PMD_ORDER above and HPAGE_PMD_ORDER from here.

Do we have a guide on when to use which?

>>
>> >       if (result != SCAN_SUCCEED) {
>> >               mmap_read_unlock(mm);
>> >               goto out_nolock;
>> > @@ -1168,7 +1170,8 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
>> >        * mmap_lock.
>> >        */
>> >       mmap_write_lock(mm);
>> > -     result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
>> > +     result = hugepage_vma_revalidate(mm, address, true, &vma, cc,
>> > +                                      BIT(HPAGE_PMD_ORDER));
>> >       if (result != SCAN_SUCCEED)
>> >               goto out_up_write;
>> >       /* check if the pmd is still valid */
>> > @@ -2807,7 +2810,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start,
>> >                       mmap_read_lock(mm);
>> >                       mmap_locked = true;
>> >                       result = hugepage_vma_revalidate(mm, addr, false, &vma,
>> > -                                                      cc);
>> > +                                                      cc, BIT(HPAGE_PMD_ORDER));
>> >                       if (result  != SCAN_SUCCEED) {
>> >                               last_fail = result;
>> >                               goto out_nolock;
>> > --
>> > 2.50.1
>> >
>>
>

-- 
Wei Yang
Help you, Help me