linux-kernel - Re: [PATCH 3/3] mm: Add kernel PTE level pagetable pages account

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]

Date:   Thu, 7 Jul 2022 19:45:29 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     akpm@...ux-foundation.org, rppt@...ux.ibm.com, will@...nel.org,
        aneesh.kumar@...ux.ibm.com, npiggin@...il.com,
        peterz@...radead.org, catalin.marinas@....com,
        chenhuacai@...nel.org, kernel@...0n.name,
        tsbogend@...ha.franken.de, dave.hansen@...ux.intel.com,
        luto@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, arnd@...db.de, guoren@...nel.org,
        monstr@...str.eu, jonas@...thpole.se,
        stefan.kristiansson@...nalahti.fi, shorne@...il.com,
        x86@...nel.org, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, loongarch@...ts.linux.dev,
        linux-mips@...r.kernel.org, linux-csky@...r.kernel.org,
        openrisc@...ts.librecores.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] mm: Add kernel PTE level pagetable pages account



On 7/6/2022 11:45 PM, Matthew Wilcox wrote:
> On Wed, Jul 06, 2022 at 04:59:17PM +0800, Baolin Wang wrote:
>> Now the kernel PTE level ptes are always protected by mm->page_table_lock
>> instead of split pagetable lock, so the kernel PTE level pagetable pages
>> are not accounted. Especially the vmalloc()/vmap() can consume lots of
>> kernel pagetable, so to get an accurate pagetable accounting, calling new
>> helpers page_{set,clear}_pgtable() when allocating or freeing a kernel
>> PTE level pagetable page.
>>
>> Meanwhile converting architectures to use corresponding generic PTE pagetable
>> allocation and freeing functions.
>>
>> Note this patch only adds accounting to the page tables allocated after boot.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
>> Reported-by: kernel test robot <oliver.sang@...el.com>
> 
> What does this Reported-by: even mean?  the kernel test robot told you
> that the page tables weren't being accounted?

I fixed an issue reported by this robot. OK, I can remove the tag.

> I don't understand why we want to start accounting kernel page tables.
> an we have a *discussion* about that with a sensible thread name instead
> of just trying to sneak it in as patch 3/3?

I think I have replied to you in below link [1]. The reason is we should 
keep consistent with PMD or PUD pagetable allocation.

[1] 
https://lore.kernel.org/all/68a5286b-7ff3-2c4e-1ab2-305e7860a2f3@linux.alibaba.com/