linux-kernel - Re: [PATCH v2 10/15] s390: pgtable: also move pagetable_dtor() of PxD to __tlb_remove

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Message-ID: <5d339eec-bb93-49ab-890f-07c77ce040d8@bytedance.com>
Date: Fri, 20 Dec 2024 16:55:05 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Alexander Gordeev <agordeev@...ux.ibm.com>
Cc: peterz@...radead.org, tglx@...utronix.de, david@...hat.com,
 jannh@...gle.com, hughd@...gle.com, yuzhao@...gle.com, willy@...radead.org,
 muchun.song@...ux.dev, vbabka@...nel.org, lorenzo.stoakes@...cle.com,
 akpm@...ux-foundation.org, rientjes@...gle.com, vishal.moola@...il.com,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org
Subject: Re: [PATCH v2 10/15] s390: pgtable: also move pagetable_dtor() of PxD
 to __tlb_remove_table()



On 2024/12/20 16:42, Alexander Gordeev wrote:
> On Wed, Dec 18, 2024 at 09:04:46PM +0800, Qi Zheng wrote:
>> In s390, the pagetable_dtor() of PTE has long been moved to
>> __tlb_remove_table().
> 
> Well, not pagetable_dtor(), but rather pagetable_pte_dtor() and
> not to __tlb_remove_table(), but to pagetable_pte_dtor_free() ;)
> 
>> So similarly, also move the pagetable_dtor() of
>> PMD|PUD|P4D to __tlb_remove_table(). This prevents the use-after-free
>> problem where the ptlock is freed immediately but the page table pages
>> is freed later via RCU.
>>
>> By the way, rename pagetable_pte_dtor_free() to pagetable_dtor_free().
> 
> This is not just a random rename, but rather a result of unifying
> PxD and PTE TLB free paths.
> 
> Could you please come up with a better wording concerning the above?

Sorry about that. Will modify it as you said above.

> 
>> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
>> Suggested-by: Peter Zijlstra (Intel) <peterz@...radead.org>
>> Cc: linux-s390@...r.kernel.org
>> ---
>>   arch/s390/include/asm/tlb.h |  3 ---
>>   arch/s390/mm/pgalloc.c      | 14 ++++----------
>>   2 files changed, 4 insertions(+), 13 deletions(-)
> 
> You also did not CC linux-s390@...r.kernel.org for other patches
> that affect s390 sources. Just CC the whole series, please.

Got it, will CC linux-s390@...r.kernel.org for the whole series in
v3.

Thanks!

> 
> Thanks!