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

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Message-ID: <Z2Ut225pJFBq2wad@li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com>
Date: Fri, 20 Dec 2024 09:42:03 +0100
From: Alexander Gordeev <agordeev@...ux.ibm.com>
To: Qi Zheng <zhengqi.arch@...edance.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 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?

> 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.

Thanks!