From: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
To: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Muhammad Usama Anjum <usama.anjum@arm.com>,
linux-s390@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com
Subject: Re: [PATCH v8 10/15] s390/mm: Cleanup pXXp_flush_lazy() routines
Date: Tue, 13 Oct 2026 15:31:09 +0200 [thread overview]
Message-ID: <20261013153109.5d5143f6@thinkpad-T15> (raw)
In-Reply-To: <964adeedfd20d4dbcc9a6341f57ec7aaac6c6adc.1791365932.git.agordeev@linux.ibm.com>
On Wed, 7 Oct 2026 13:41:53 +0200
Alexander Gordeev <agordeev@linux.ibm.com> wrote:
> Avoid unnecessary pgtable entry read in ptep_flush_lazy() and
> pmdp_flush_lazy() routines. Use the already obtained value of
> a pgtable entry instead of dereferencing it again.
>
> It might appear that the optimized out second dereferencing happens
> under mm_context_t::flush_count lock and therefore a race condition
> is possible. However, both routines write invalid entry bits to the
> pgtable entries and therefore no reader is allowed to interpret the
> rest of the value afterwards.
>
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
> ---
> arch/s390/mm/pgtable.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
Looks good to me.
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
next prev parent reply other threads:[~2026-10-13 13:31 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-07 11:41 [PATCH v8 00/15] s390/mm: Batch PTE updates in lazy MMU mode Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 01/15] mm: introduce hw_pte_t for PTE table storage Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 02/15] mm: rename pointers to software PTE values as ptentp Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 03/15] mm: use hw_pte_t for generic PTE table storage Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 04/15] mm: convert PTE table entries in ptep_get() Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 05/15] mm: convert PTE table entry to pte Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 06/15] mm: add hw_pte_val for HW PTE storage Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 07/15] mm/kasan: use hw_pte_t for the early shadow PTE table Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 08/15] drm/i915: use hw_pte_t for PTE range callbacks Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 09/15] xen: " Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 10/15] s390/mm: Cleanup pXXp_flush_lazy() routines Alexander Gordeev
2026-10-13 13:31 ` Gerald Schaefer [this message]
2026-10-13 14:43 ` Heiko Carstens
2026-10-07 11:41 ` [PATCH v8 11/15] s390: Distinguish hardware and software PTEs Alexander Gordeev
2026-10-08 10:32 ` kernel test robot
2026-10-07 11:41 ` [PATCH v8 12/15] mm: Make lazy MMU mode context-aware Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 13/15] s390/mm: Batch PTE updates in lazy MMU mode Alexander Gordeev
2026-10-07 11:41 ` [PATCH v8 14/15] mm/kasan: Introduce helpers for lazy MMU mode sanitizer Alexander Gordeev
2026-10-07 20:24 ` kernel test robot
2026-10-07 20:35 ` kernel test robot
2026-10-08 1:11 ` kernel test robot
2026-10-07 11:41 ` [PATCH v8 15/15] s390/mm: Lazy " Alexander Gordeev
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